UDP Speed Test Protocol for One-way IP Capacity Metric Measurement
draft-ietf-ippm-capacity-protocol-25
| Document | Type | Active Internet-Draft (ippm WG) | |
|---|---|---|---|
| Authors | Len Ciavattone , Ruediger Geib | ||
| Last updated | 2025-09-30 (Latest revision 2025-09-16) | ||
| Replaces | draft-morton-ippm-capacity-metric-protocol | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Proposed Standard | ||
| Formats | |||
| Reviews |
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| Additional resources |
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| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Tommy Pauly | ||
| Shepherd write-up | Show Last changed 2025-05-21 | ||
| IESG | IESG state | RFC Ed Queue | |
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| Consensus boilerplate | Yes | ||
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| Responsible AD | Mohamed Boucadair | ||
| Send notices to | tpauly@apple.com | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | RFC-Ed-Ack | ||
| IANA expert review state | Expert Reviews OK | ||
| IANA expert review comments | The port expert recommends changing the service name to "udpstp," adding, "the words protocol and service are redundant in service names - all service names are both." | ||
| RFC Editor | RFC Editor state | EDIT | |
| Details |
draft-ietf-ippm-capacity-protocol-25
Network Working Group L. Ciavattone
Internet-Draft AT&T Labs
Intended status: Standards Track R. Geib
Expires: 20 March 2026 Deutsche Telekom
16 September 2025
UDP Speed Test Protocol for One-way IP Capacity Metric Measurement
draft-ietf-ippm-capacity-protocol-25
Abstract
This document addresses the problem of protocol support for measuring
One-Way IP Capacity metrics specified by RFC 9097. The Method of
Measurement discussed there requires a feedback channel from the
receiver to control the sender's transmission rate in near-real-time.
This document defines the UDP Speed Test Protocol for conducting RFC
9097 and other related measurements.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 20 March 2026.
Copyright Notice
Copyright (c) 2025 IETF Trust and the persons identified as the
document authors. All rights reserved.
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This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Scope, Goals, and Applicability . . . . . . . . . . . . . . . 4
3. Protocol Overview . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Fixed-Rate Testing . . . . . . . . . . . . . . . . . . . 10
3.2. Handling of and Safeguards required by Self-Induced
Congestion . . . . . . . . . . . . . . . . . . . . . . . 10
4. Requirements, Security Operations, and Optional Checksum . . 11
4.1. Load Rate Adjustment Algorithm Requirements . . . . . . . 11
4.2. Parameters and Definitions . . . . . . . . . . . . . . . 13
4.3. Security Mode Operations . . . . . . . . . . . . . . . . 13
4.3.1. Mode 1: Required Authenticated Mode . . . . . . . . . 14
4.3.2. Mode 2: Optional Authenticated Mode for Data Phase . 15
4.4. Key Management . . . . . . . . . . . . . . . . . . . . . 16
4.4.1. Key Derivation Function (KDF) . . . . . . . . . . . . 16
4.5. Configuration of Network Functions with Stateful
Filtering . . . . . . . . . . . . . . . . . . . . . . . . 18
4.6. Optional Checksum . . . . . . . . . . . . . . . . . . . . 19
5. Test Setup Request and Response . . . . . . . . . . . . . . . 20
5.1. Client Generates Test Setup Request . . . . . . . . . . . 20
5.2. Server Test Setup Request Processing and Response
Generation . . . . . . . . . . . . . . . . . . . . . . . 23
5.2.1. Test Setup Request Processing - Rejection . . . . . . 24
5.2.2. Test Setup Request Processing - Acceptance . . . . . 27
5.3. Setup Response Processing at the Client . . . . . . . . . 29
6. Test Activation Request and Response . . . . . . . . . . . . 30
6.1. Client Generates Test Activation Request . . . . . . . . 30
6.2. Server Processes Test Activation Request and Generates
Response . . . . . . . . . . . . . . . . . . . . . . . . 36
6.2.1. Server Rejects or Modifies Request . . . . . . . . . 36
6.2.2. Server Accepts Request and Generates Response . . . . 37
6.3. Client Processes Test Activation Response . . . . . . . . 38
7. Test Load Stream Transmission and Measurement Status Feedback
Messages . . . . . . . . . . . . . . . . . . . . . . . . 39
7.1. Load PDU and Roles . . . . . . . . . . . . . . . . . . . 39
7.2. Status PDU . . . . . . . . . . . . . . . . . . . . . . . 44
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8. Stopping a Test . . . . . . . . . . . . . . . . . . . . . . . 51
9. Operational considerations for the Measurement Method . . . . 52
9.1. Notes on Interface Measurements . . . . . . . . . . . . . 53
10. Security Considerations . . . . . . . . . . . . . . . . . . . 53
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 55
11.1. New User Port Number Assignment . . . . . . . . . . . . 55
11.2. New KeyTable KDF . . . . . . . . . . . . . . . . . . . . 55
11.3. New UDPSTP Registry Group . . . . . . . . . . . . . . . 55
11.3.1. PDU Identifier Registry . . . . . . . . . . . . . . 56
11.3.2. Protocol Version Registry . . . . . . . . . . . . . 57
11.3.3. Test Setup PDU Modifier Bitmap Registry . . . . . . 57
11.3.4. Test Setup PDU Authentication Mode Registry . . . . 58
11.3.5. Test Setup PDU Command Response Field Registry . . . 59
11.3.6. Test Activation PDU Command Request Registry . . . . 61
11.3.7. Test Activation PDU Modifier Bitmap Registry . . . . 61
11.3.8. Test Activation PDU Rate Adjustment Algo.
Registry . . . . . . . . . . . . . . . . . . . . . . 62
11.3.9. Test Activation PDU Command Response Field
Registry . . . . . . . . . . . . . . . . . . . . . . 63
11.4. Guidelines for the Designated Experts . . . . . . . . . 64
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 64
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 64
13.1. Normative References . . . . . . . . . . . . . . . . . . 64
13.2. Informative References . . . . . . . . . . . . . . . . . 66
Appendix A. KDF Example (OpenSSL) . . . . . . . . . . . . . . . 67
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 69
1. Introduction
The performance community has seen development of Informative Bulk
Transport Capacity definitions in the "Framework for Bulk Transport
Capacity" (BTC, see [RFC3148]) and for "Network Capacity and Maximum
IP-layer Capacity" [RFC5136]. "Model-Based Metrics for BTC" add
experimental metric definitions and methods in [RFC8337].
This document specifies the UDP Speed Test Protocol (UDPSTP) enabling
the measurement of One-Way IP Capacity metrics as defined by
[RFC9097]. The Method of Measurement discussed there deploys a
feedback channel from the receiver to control the sender's
transmission rate in near-real-time. Section 8.1 of [RFC9097]
specifies requirements for this method.
This protocol supports measurement features which weren't available
by TCP based speed tests and standard measurement protocols like One
Way Active Measurement Protocol (OWAMP) [RFC4656], Two-Way Active
Measurement Protocol (TWAMP) [RFC5357] and Simple Two-Way Active
Measurement Protocol (STAMP) [RFC8762] prior to this work. The
controlled Bulk Capacity measurement or Speed Test, respectively, is
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based on UDP rather than TCP. The bulk measurement load is
unidirectional. These specifications did support creation of
asymmetric traffic in combination with some two-way communication, as
supported by TWAMP and STAMP, when work on UDPSTP started. Further,
two-way communications of TWAMP and STAMP are limited to reflection
or unidirectional load properties, but lack support for closed loop
feedback operation. The latter enables limiting congestion of a
bottleneck, whose capacity is measured, to a short time range.
Support of such a control loop is the main purpose of UDPSTP.
Apart from measurement functionality, a Key Derivation Function has
been added providing cryptographic separation of key material for
authentication of protocol messages in a standardized and
cryptographically secure manner. This is a secondary improvement
reached by UDPSTP and may simplify its reuse for other measurement
purposes. Additionally, because the protocol uses synthetic payload
data and contains no direct user information, a decision was made to
forgo encryption support. Secondarily, this is also expected to
increase the number of low-end devices that can support the test
methodology.
1.1. Terminology
Downstream UDP Speed Test: A client initiated Network Capacity
measurement between a server acting as sender and a client acting as
receiver.
Upstream UDP Speed Test: A client initiated Network Capacity
measurement between a client acting as sender and a server acting as
receiver.
1.2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119], [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Scope, Goals, and Applicability
The scope of this document is to define a protocol to measure the
Maximum IP-Layer Capacity metric according to the Method of
Measurement standardized by Section 8 of [RFC9097]. As such, this
document adheres to the applicability scope defined in Section 2 of
[RFC9097].
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Some aspects of this protocol and end-host configuration can lead to
support of additional forms of measurement, such as application
emulation enabled by creative use of the load rate adjustment
algorithm. Per [RFC9097], that algorithm must not be used as a
general Congestion Control Algorithm (CCA). Instead, the load rate
adjustment algorithm's goal is to help determine the Maximum IP-Layer
Capacity in the context of an infrequent, diagnostic, short-term
measurement.
The goal is to harmonize the specified IP-Layer Capacity metric and
method across the industry, and this protocol supports the
specifications of IETF ([RFC9097]) and other Standards Development
Organizations (SDO's; see, e.g., [TR-471]).
The primary application of the protocol described here is the same as
in Section 2 of [RFC7497] where:
* The access portion of the network is the focus of this problem
statement. The user typically subscribes to a service with
bidirectional access partly described by rates in bits per second.
UDPSTP is a client-based protocol. It may be applied by consumers to
measure their own access bandwidth. Consumers may prefer an
independent 3rd party domain hosting the measurement server for this
purpose. UDPSTP may be deployed in Large-Scale Measurement of
Broadband Performance environments (LMAP, see [RFC7497]), another
independent 3rd party domain measurement server deployment. A
network operator may support operation and maintenance by UDPSTP, a
typical intra-domain deployment. All these deployments require or
benefit from trust into the results, which are ensured by
authenticated communication.
3. Protocol Overview
All messages defined by this document SHALL use UDP transport.
The remainder of this section gives an informative overview of the
communication protocol between two test endpoints (without expressing
requirements or elaborating on the authentication aspects).
One endpoint takes the role of server, listening for connection
requests on a standard UDP Speed Test Protocol port number from the
other endpoint, the client.
The client requires configuration of a test direction parameter
(upstream or downstream test, where the client performs the role of
sender or receiver, respectively) as well as the hostname or IP
address(es) of the server(s) in order to begin the setup and
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configuration exchanges with the server(s). By default, the client
uses the single, standard UDPSTP port number per connection (see
Section 5). If the default port number is not used, the client may
require configuration of the control port number used by each server.
This would be the case if multiple server instances (processes)
operate on one or more machines.
Additionally, multi-connection (multi-flow) testing is supported by
the protocol. Each connection is independent and attempts to
maximize its own individual traffic rate. For multi-connection
tests, a single client process would replicate the connection setup
and test procedure multiple times (once for each flow) to one or more
server instances. The server instance(s) would process each
connection independently, as if they were coming from separate
clients. It shall be the responsibility of the client process to
manage the inter-related connections: handling the individual
connection setup successes and failures, cleaning up connections
during a test (should some fail) as well as aggregate the individual
test results into an overall set of performance statistics. Fields
in the Setup Request (mcIndex, mcCount, and mcIdent, see Section 6.1)
are used to both differentiate and associate the multiple connections
that comprise a single test.
The protocol uses UDP transport [RFC0768] with two connection phases
(Control and Data). The exchanges 1 and 2 (see below) constitute the
Control phase, while exchanges 3 and 4 constitute the Data phase. In
this document, the term message and the term Protocol Data Unit, or
PDU ([RFC5044]) are used interchangeably.
1. Test Setup Request and Response: If a server instance is
identified with a host name that resolves to both IPv4/IPv6
addresses, it is recommended to use the first address returned in
the name resolution response - regardless, whether it's IPv4 or
IPv6. Thus, the decision on the preferred IP address family is
left to the name resolver's default behavior. Support for
separate IPv4 and IPv6 measurements or an IPv4 and IPv6 multi
connection setup are left for future improvement. The client
then requests to begin a test by communicating its UDPSTP
protocol version, intended security mode, and datagram size
support. The server either confirms matching a configuration or
rejects the connection request. If the request is accepted, the
server provides a unique ephemeral port number for each test
connection, allowing further communication. In a multi-
connection setup, distinct UDP port numbers may be assigned with
each Setup Response from a server instance. Distinct UDP port
numbers will be assigned if all Setup Response messages originate
from the same server in that case.
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2. Test Activation Request and Response: After having received a
confirmation of the configuration by a server, the client
composes a request conveying parameters such as the testing
direction, the duration of the test interval and test sub-
intervals, and various thresholds (for a detailed discussion, see
[RFC9097] and [TR-471]). The server then chooses to accept,
ignore or modify any of the test parameters, and communicates the
set that will be used unless the client rejects the
modifications. Note that the client assumes that the Test
Activation exchange has opened any co-located firewalls and
network address/port translators for the test connection (in
response to the Request packet on the ephemeral port number) and
the traffic that follows. See [RFC9097] for a more detailed
discussion of firewall and NAT related features. If the Test
Activation Request is rejected or fails, the client assumes that
the firewall will close the address/port number pinhole entry
after the firewall's configured idle traffic timeout.
3. Test Stream Transmission and Measurement Feedback Messages:
Testing proceeds with one endpoint sending Load PDUs and the
other endpoint receiving the Load PDUs and sending frequent
status messages to communicate status and reception conditions
there. The data in the feedback messages, whether received from
the client or when being sent to the client, is input to a load
rate adjustment algorithm at the server which controls future
sending rates at either end. The choice to locate the load rate
adjustment algorithm at the server, regardless of transmission
direction, means that the algorithm can be updated more easily at
a host within the network, and at a fewer number of hosts than
the number of clients. Note that the status messages also help
keep the pinhole (or mapping, respecitvely) active at on-path
stateful devices. UDPSTP is at least partially compliant to
section 3.1 of [RFC8085]: if the bottleneck is congested, but
pending congestion is avoided by limiting the duration of that
congestion to the minimum required to determine the bottleneck
capacity.
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4. Stopping the Test: When the specified test duration has been
reached, the server initiates the exchange to stop the test by
setting a STOP indication in its outgoing Load PDUs or Status
Feedback messages. After being received, the client acknowledges
it by also setting a STOP indication in its outgoing Load PDUs or
Status Feedback messages. A graceful connection termination at
each end then follows. Since the Load PDUs and Status Feedback
messages are used, this exchange is considered a sub-exchange of
3. If the Test traffic stops or the communication path fails,
the client assumes that the firewall will close the address/port
number combination after the firewall's configured idle traffic
timeout.
5. Both the client and server react to unexpected interruptions in
the Control or Data phase, respectively. Watchdog timers limit
the time a server or client will wait before stopping all traffic
and terminating a test.
Figure 1 provides an example exchange of control and measurement PDUs
for both a downstream and upstream UDP Speed Tests (always client
initiated):
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=========== Downstream Test ===========
+---------+ +---------+
| Client | Test Setup Request -----> | Server |
+---------+ +---------+
<----- Test Setup Response (Accept)
<----- Null Request PDU
Test Activation Request ----->
<----- Test Activation Response (Accept)
<----- Load PDUs
Status Feedback PDUs ----->
After expiry of server's test duration timer...
<----- Load PDU (TEST_ACT_STOP)
Status Feedback PDU (TEST_ACT_STOP) ----->
============ Upstream Test ============
+---------+ +---------+
| Client | Test Setup Request -----> | Server |
+---------+ +---------+
<----- Test Setup Response (Accept)
<----- Null Request PDU
Test Activation Request ----->
<----- Test Activation Response (Accept)
Load PDUs ----->
<----- Status Feedback PDUs
After expiry of server's test duration timer...
<----- Status Feedback PDU (TEST_ACT_STOP)
Load PDU (TEST_ACT_STOP) ----->
Figure 1: Successful UDPSTP Message Exchanges
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3.1. Fixed-Rate Testing
A network operator who is certain of the IP-Layer Capacity to be
validated, can execute a fixed-rate test of the IP-Layer Capacity and
avoid activating the measurement load rate adjustment algorithm (see
section 8.1 of [RFC9097]). Fixed-rate testing SHOULD only be
activated for operation and maintenance purposes by operators within
their local network domain.
If a subscriber requests a diagnostic test from the network operator,
this strongly implies that there is no certainty on the bottleneck
capacity and initiating a UDP Speed Test based on the load adjustment
algorithm is RECOMMENDED. To protect against misuse, a client (and
in general, a consumer) MUST NOT be able to initiate a fixed-rate
test. A network operator may conduct a fixed-rate test for a stable
measurement at or near the maximum determined by the load rate
adjustment algorithm for debugging purposes. This may be valuable
for post-installation or post-repair verification.
3.2. Handling of and Safeguards required by Self-Induced Congestion
Active capacity measurement requires inducing intentional congestion.
On paths where the capacity bottleneck is not shared with other
flows, this self-congestion will be observed as loss and/or delay.
However, when a path is shared by other flows, the measurment traffic
can congest the bottleneck on the path and therefore can degrade the
performance of other flows. Unrestricted use of the tool could lead
to traffic starvation and significant issues.
Measurements that generate traffic on shared paths (including WiFi
and Internet paths) need to consider the impact on other traffic.
Fixed-rate testing operates without congestion control and therefore
must not be executed over other operators network segments. Fixed-
rate testing therefore is limited to paths within a domain entirely
managed and operated section-wise and end-to-end by the network
operator performing the measurement. When the risks of disruption to
other flows has been considered, testing could be extended to include
adjacent operational domains for which there is also a testing
agreement.
Concurrent tests that congest a common bottleneck will impair the
measurement and result in additional congestion. Concurrent
measurements to measure the maximum capacity on a single path are
counterproductive. The number of concurrent independent tests of a
path SHALL be limited to one, regardless of the number of flows.
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A load rate adjustment algorithm (see section 4.1) is required to
mitigate the impact of this congestion and to limit the duration of
any congestion by terminating the test when sudden impairments or a
loss of connectivity is detected.
4. Requirements, Security Operations, and Optional Checksum
Security and checksum operation aren't covered by [RFC9097], which
only defines the Method of Measurement. This section adds the
operational specification related to security and optional checksum.
Due to the additional complexities, and loss of the direct Layer 3 to
Layer 4 mapping of packets to datagrams, it is recommended that Layer
3 fragmentation be avoided. A simplified approach is to choose the
default datagram size small enough to prevent fragmentation. This
version of the specification does not support Packetization Layer
Path MTU Discovery for Datagram Transports (DPLPMTUD) [RFC8899]. A
future version could specify how to support this. DPLPMTUD support
will require a carefully adapted protocol design to ensure
interoperability. Unless IP fragmentation is expected, and is one of
the attributes being measured, the IPv4 DF bit SHOULD be set for all
tests.
Note: When this specification is used for network debugging, it may
be useful for fragmentation to be under the control of the test
administrator.
This section specifies generic requirements which a measurement load
rate adjustment algorithm conforming to this specification MUST
fulfill.
4.1. Load Rate Adjustment Algorithm Requirements
This document specifies an active capacity measurement method using a
load rate adjustment algorithm. The requirements following below and
the currently standardised load rate adjustment algorithms B
[Y.1540Amd2] and C [TR-471] result from years of experiments and
testing by the original authors. These tests were performed in Labs,
but also in the Internet and covered a set of different fixed,
broadband, mobile and wireless access types and technologies in
different countries and continents. Feedback received by performance
measurement experts was included, as well as changes resulting from
the standardisation of [RFC9097] (reflected also in algorithm B
[Y.1540Amd2], which updates a prior version of this algorithm).
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Load rate adjustment algorithms for capacity measurement MUST comply
with the requirements specified by this section. New standard load
rate adjustment algorithms for capacity measurement MUST be reviewed
by IETF designated experts prior to assignment of a codepoint in the
IETF Test Activation PDU Rate Adjustment Algorithm Registry.
Load rate adjustment algorithm for capacity measurement requirements:
1. The measurement load rate adjustment algorithm described in this
section MUST NOT be used as a general Congestion Control
Algorithm (CCA).
2. This specification MUST only be used in the application of
diagnostic and operations measurements.
3. Both, Load PDU messages and Status Feedback PDU messages MUST
contain sequence numbers.
4. The nominal duration of a measurement interval at the
Destination, testIntTime (I in [RFC9097]), MUST default to a
value of no more than 10 seconds.
5. A high-speed mode to achieve high sending rates quickly MUST
reduce the measurement load below a level for which the first
feedback interval inferred "congestion" from the measurements.
Consecutive feedback intervals that have a supra-threshold count
of sequence number anomalies and/or contain an upper delay
variation threshold exception in all of the consecutive
intervals, indicate "congestion" within a test. The threshold
of consecutive feedback intervals SHALL be configurable with a
default of 3 intervals and a maximum duration to infer
congestion of 500 ms.
6. Congestion MUST be indicated, if the Status Feedback PDUs either
indicate that sequence number anomalies were detected OR the
delay range was above the upper delay variation threshold. The
RECOMMENDED threshold values are 10 for sequence number gaps and
30 ms for lower and 90 ms for upper delay variation thresholds,
respectively.
7. The load rate adjustment algorithm MUST include a Load PDU
timeout and a Status PDU timeout which both stop the test when
received PDU streams cease unexpectedly.
8. The Load PDU timeout SHALL be reset to the configured value each
time a Load PDU is received. If the Load PDU timeout expires,
the receiver SHALL be closed and no further Status PDU feedback
sent. The default Load PDU timeout MUST be no more than 1 sec.
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9. The Status PDU timeout SHALL be reset to the configured value
each time a feedback message is received. If the Status PDU
timeout expires, the sender SHALL be closed and no further load
packets sent. The default Status PDU timeout timeout MUST be no
more than 1 second.
10. If a network operator is certain of the IP-Layer Capacity to be
validated, then testing MAY start with a fixed-rate test at the
IP-Layer Capacity and avoid activating the measurement load rate
adjustment algorithm (see section 8.1 of [RFC9097]). However,
the stimulus for a diagnostic test (such as a subscriber
request) strongly implies that there is no certainty, and the
load adjustment algorithm is RECOMMENDED.
11. This specification MUST only be used in circumstances consistent
with Section 10 of [RFC9097] ("Security Considerations").
12. Further measurement load rate adjustment algorithm requirements
are specified by [RFC9097].
The following measurement load rate adjustment algorithms are subject
to these requirements:
* Measurement load rate adjustment algorithm B [Y.1540Amd2].
* Measurement load rate adjustment algorithm C [TR-471].
4.2. Parameters and Definitions
Please refer to Section 4 of [RFC9097] for an overview of Parameters
related to the Maximum IP-Layer Capacity Metric and Method. A set of
error-codes to support debugging are provided in Section 11.3.5.
4.3. Security Mode Operations
There are two security modes of operation that perform authentication
of the client/server messaging. The two modes are:
1. A REQUIRED mode with authentication during the Control phase
(Test Setup and Test Activation exchanges). This mode may be
preferred for large-scale servers or low-end client devices where
processing power is a consideration (see Section 2).
2. An OPTIONAL mode with the additional authentication of the Status
Feedback messages during the Data phase. This mode may be
preferred for environments that desire an additional level of
message integrity verification throughout the test (see
Section 2).
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The requirements discussed hereafter refer to the PDUs in sections 5
and 6 below, primarily the authMode, keyId, authUnixTime, and
authDigest fields. The roles in this section have been generalized
so that the requirements for the PDU sender and receiver can be re-
used and referred to by other sections within this document. Each
successive mode increases security, but comes with additional
performance impacts and complexity. The protocol is used with
unsubstantial payload and it may operate on very low-end devices.
Offering the flexibility of various security operation modes allows
for accommodation of available end-device resources. In general, an
active measurement technique as the one defined by this document is
better suited to protect the privacy of those involved in
measurements [RFC7594].
A load rate adjustment method needs to satisfy the requirements
listed in Section 4.1. This is necessary also to avoid potentially
inducing congestion after there is an overload or loss (including
loss on the control path).
4.3.1. Mode 1: Required Authenticated Mode
In this mode, the client and the server SHALL be configured to use
one of a number of shared secret keys, designated via the numeric
keyId field (see Section 4.4). This key SHALL be used as input to
the KDF (Key Derivation Function), as specified in Section 4.4.1, to
obtain the actual keys used by the client and server for
authentication.
During the Control phase, the sender SHALL read the current system
(wall-clock) time and populate the authUnixTime field and next
calculate the 32-octet HMAC-SHA-256 hash of the entire PDU according
to section 6 of [RFC6234] (with the authDigest and checkSum preset to
all zeroes). The authDigest field is filled by the result, then the
packet is sent to the receiver. The value in the authUnixTime field
is a 32-bit timestamp and a 10-second tolerance window (+/- 5
seconds) SHALL be used by the receiver to distinguish a subsequent
replay of a PDU. See Table 2 of [TR-471] for a recommended timestamp
resolution.
Upon reception, the receiver SHALL validate the message PDU for
correct length, validity of authDigest, immediacy of authUnixTime,
and expected formatting (PDU-specific fields are also checked, such
as protocol version). Validation of the authDigest requires that it
will be extracted from the PDU and the field, along with the checkSum
field, zeroed prior to the HMAC calculation used for comparison (see
section 7.2 of [RFC9145]).
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If the validation fails, the receiver SHOULD NOT continue with the
Control phase and implement silent rejection (no further packets sent
on the address/port pairs). The exception is when the testing hosts
have been configured for troubleshooting Control phase failures and
rejection messages will aid in the process.
If the validation succeeds, the receiver SHALL continue with the
Control phase and compose a successful response or a response
indicating the error conditions identified (if any).
This process SHALL be executed for the request and response in the
Test Setup exchange, including the Null Request (Section 5) and the
Test Activation exchange (Section 6).
4.3.2. Mode 2: Optional Authenticated Mode for Data Phase
This mode incorporates Authenticated mode 1. When using the optional
authentication during the Data phase, authentication SHALL also be
applied to the Status Feedback PDU (see Section 7.2). The client
sends the Status PDU in a downstream test, and the server sends it in
an upstream test.
The Status PDU sender SHALL read the current system (wall-clock) time
and populate the authUnixTime field, then calculate the authDigest
field of the entire Status PDU (with the authDigest and checkSum
preset to all zeroes) and send the packet to the receiver. The
values of authUnixTime field and authDigest field are determined as
defined by Section 4.3.1.
Upon reception, the receiver SHALL validate the message PDU for
correct length, validity of authDigest, immediacy of authUnixTime,
and expected formatting (PDU-specific fields are also checked, such
as protocol version). Validation of the authDigest will require that
it be extracted from the PDU and the field, along with the checkSum
field, zeroed prior to the HMAC calculation used for comparison.
If the authentication validation fails, the receiver SHALL ignore the
message. If the watchdog timer expires (due to successive failed
validations), the test session will prematurely terminate (no further
load traffic SHALL be transmitted). This is necessary also to avoid
potentially inducing congestion after there is an overload or loss on
the control path.
If this optional mode has not been selected, then the keyId,
authUnixTime, and authDigest fields of the Status PDU (see
Section 7.2) SHALL be set to all zeroes.
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4.4. Key Management
Section 2 of [RFC7210] specifies a conceptual database for long-lived
cryptographic keys. The key table SHALL be used with the REQUIRED
authentication mode and the OPTIONAL authentication mode (using the
same key). For authentication, this key SHALL only be used as input
to the KDF, specified in Section 4.4.1, to derive the actual keys
used for authentication processing. Key rotation and related
management specifics are beyond the scope of this document.
The key table SHALL have (at least) the following fields, referring
to Section 2 of [RFC7210]:
* AdminKeyName
* LocalKeyName
* KDF
* AlgID
* Key
* SendLifetimeStart
* SendLifetimeEnd
* AcceptLifetimeStart
* AcceptLifetimeEnd
The LocalKeyName SHALL be determined from the corresponding keyId
field in the PDUs that follow.
4.4.1. Key Derivation Function (KDF)
A Key Derivation Function (KDF) is a one-way function that provides
cryptographic separation of key material. The protocol requires a
KDF to securely derive cryptographic keys used for authentication of
protocol messages. The inclusion of a KDF ensures that keys are
generated in a standardized, cryptographically secure manner,
reducing the risk of key compromise and enabling interoperability
across implementations. The benefits of using a KDF include:
* Security: A KDF produces keys with high entropy, resistant to
brute-force and related-key attacks, ensuring robust protection
for protocol communications.
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* Flexibility: The KDF allows derivation of multiple keys from a
single shared secret, supporting distinct keys for client and
server authentication.
* Standardization: By adhering to established cryptographic
standards, the KDF ensures compatibility with existing security
frameworks and facilitates implementation audits.
* Efficiency: The KDF enables efficient key generation without
requiring additional key exchange mechanisms, minimizing protocol
overhead.
The KDF algorithm SHALL be a Key Derivation Function in Counter Mode,
as specified in Section 4.1 of [NIST800-108]. This algorithm uses a
counter-based mechanism to generate key material from a shared
secret, ensuring deterministic and secure key derivation. The
Pseudorandom Function (PRF) used in the KDF SHALL be HMAC-SHA-256, as
defined in section 6 of [RFC6234]. IANA is asked to assign “HMAC-
SHA-256” as a new KeyTable KDF (Section 11.2).
The KDF SHALL use the following parameters:
* Kin (Key-derivation key): The shared key as identified by the
keyId field in the PDU.
* Label: The fixed string "UDPSTP" (without quotes), encoded as a
UTF-8 string, used to bind the derived keys to this specific
protocol.
* Context: The UTF-8 string representation of the authUnixTime field
received in the very first Setup Request PDU sent from the client
to the server. This ensures that the derived keys are unique to
the session and tied to the temporal context of the initial setup
exchange. The authUnixTime field serves as a nonce and is
protected from modification by the HMAC-SHA-256 hash present in
the authDigest field.
* r: The length of the binary encoding of the counter SHALL be 32
(bits).
The total derived key material SHALL be 512 bits (64 octets) in
length. The key material SHALL be structured as follows, from most
significant bit (MSB) to least significant bit (LSB):
* Client Authentication Key: 256 bits (32 octets), used for
authenticating messages sent by the client.
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* Server Authentication Key: 256 bits (32 octets), used for
authenticating messages sent by the server.
This structure ensures that the derived keys are sufficient for
securing authentication operations within the protocol, while
maintaining clear separation of function and directionality.
If authentication of the initial Setup Request PDU received by the
server fails, due to an invalid authDigest field, any and all derived
keying material and keys SHALL be considered invalid.
The key material derived from the initial Setup Request PDU, either
at the client prior to transmission or at the server upon reception,
SHALL be used for all subsequent PDUs sent between them for that test
connection. As such, the KDF is only required to be executed once by
the client and server for each test connection.
Appendix A, Figure 12 provides a code snippet demonstrating
derivation of the specified keys from key material using the OpenSSL
cryptographic library. Specifically, the high-level Key-Based
EVP_KDF implementation (Key-Based Envelope Key Derivation Function,
see [EVP_KDF-KB] for details).
4.5. Configuration of Network Functions with Stateful Filtering
Successful interaction with a local firewall assumes the firewall is
configured to allow a host to open a bidirectional connection using
unique source and destination addresses as well as port numbers by
sending a packet using that 4-tuple for a given transport protocol.
The client's interaction with its firewall depends on this
configuration.
The firewall at the server MUST be configured with an open pinhole
for the server IP address and standard UDP port of the server. All
messages sent by the client to the server use this standard UDP port.
The server uses one ephemeral UDP port per test connection. Assuming
that the firewall administration at the server does not allow an open
UDP ephemeral port range, then the server MUST send a Null Request to
the client from the ephemeral port communicated to the client in the
Test Setup Response. The Null Request may not reach the client: it
may be discarded by the client's firewall.
If the server firewall administration allows an open UDP ephemeral
port range, then the Null Request is not strictly necessary.
However, the availability of an open port range policy cannot be
assumed.
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Network Address Translators (NATs) are expected to offer support of a
wider set of operational configurations as compared to Firewalls.
Specifications covering NAT behaviour apart from the above are out of
scope of this document, as are combined implementations of NAT and
firewalls too.
4.6. Optional Checksum
The protocol MUST utilize the standard UDP checksum for all IPv4 and
IPv6 datagrams it sends. The purpose of this checksum is to protect
the intended recipient as well as other recipients to whom a
corrupted packet may be delivered. This provides:
* Protection of the endpoint transport state from unnecessary extra
state (e.g., Invalid state from rogue packets).
* Protection of the endpoint transport state from corruption of
internal state.
* Pre-filtering by the endpoint of erroneous data, to protect the
transport from unnecessary processing and from corruption that it
can not itself reject.
* Pre-filtering of incorrectly addressed destination packets, before
responding to a source address.
All of the PDUs exchanged between the client and server support an
optional header checksum that covers the various fields in the UDPSTP
PDU (excluding the Payload Content of the Load PDU and, to be clear,
also the IP- and UDP-header). The calculation is the same as the
16-bit one's complement Internet checksum used in the IPv4 packet
header (see section 3.1 of [RFC0791]). This checksum is intended for
environments where UDP data integrity may be uncertain. This
includes situations where the standard UDP checksum is not verified
upon reception or a nonstandard network API is in use (things
typically done to improve performance on low-end devices). However,
all UDPSTP datagrams transmitted via IPv4 or IPv6 SHALL include a
standard UDP checksum to protect other potential recipients to whom a
corrupted packet may be delivered. In the case of a nonstandard
network API, one option to reduce processing overhead may be to
restrict testing to only utilize a Payload Content of all zeros so
that the UDP checksum calculation need not include it for Load PDUs.
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If a PDU sender is populating the checkSum field, it SHALL do so as
the last step after the PDU is built in all other respects (with the
checkSum field set to zero prior to the calculation). The PDU
receiver SHALL subsequently verify the PDU checksum whenever checksum
processing has been configured and the field is populated. If PDU
checksum validation fails, the PDU SHALL be discarded.
Because of the redundancy when used in conjunction with
authentication, it is OPTIONAL for a PDU sender to utilize the UDPSTP
checkSum field. However, because authentication is not applicable to
the Load PDU, the checkSum field SHALL be utilized by the sender
whenever UDP data integrity may be uncertain (as outlined above).
5. Test Setup Request and Response
The client source IP address and the server destination IP address
MUST NOT be a broadcast or multicast address. Any Test Setup Request
or Test Setup Response packet containing a multicast or broadcast
source or destination IP address MUST be silently dropped and
ignored.
The measurement method and the protocol specified by this document
are expected to function with unicast and anycast IP addresses.
5.1. Client Generates Test Setup Request
The client SHALL begin the Control phase exchange by sending a Test
Setup Request message to the server's (standard) control port. This
standard UDPSTP port number is utilized for each connection of a
multi-connection test.
The client SHALL simultaneously start a test initiation timer so that
if the Control phase fails to complete Test Setup and Test Activation
exchanges in the allocated time, the client software SHALL exit
(close the UDP socket and indicate an error message to the user).
Lost messages result in a Test Setup and Test Activation failure.
The test initiation timer MAY reuse the test termination timeout
value.
The watchdog timeout is configured as a 1-second interval to trigger
a warning message that the received traffic has stopped. The test
termination timeout is based on the watchdog interval, and implements
a wait time of 2 additional seconds before triggering a non-graceful
termination.
Note: Any field labeled as 'reserved for alignment', in any PDU, MUST
be set to 0 and MUST be ignored upon receipt.
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The UDP PDU format layout SHALL be as follows (big-endian AB,
starting by most significant byte ending by least significant byte):
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| pduId | protocolVer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| mcIndex | mcCount | mcIdent |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| cmdRequest | cmdResponse | maxBandwidth |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| testPort |modifierBitmap | authMode |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| authUnixTime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. authDigest (32-octet) .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| keyId | reservedAuth1 | checkSum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Test Setup PDU Layout
Additional details regarding the Setup Request and Response fields
are as follows:
pduId: A two-octet field. IANA is asked to assign the value hex
0xACE1 (Section 11.3.1).
protocolVer: A two-octet field, identifying the actual protocol
version. IANA is asked to assign only one initial value, 20
(Section 11.3.2).
mcIndex: A one-octet field, indicating the index of a connection
relative to all connections that make up a single test (starting at
0, incremented by 1 per connection). It is used to differentiate
separate connections within a multi-connection test. An
implementation may restrict the number of connections supported for a
single test to a value less than or equal to 255.
mcCount: A one-octet field, indicating the total count of connections
that the client is attempting to setup.
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mcIdent: A two-octet field containing a pseudorandom non-zero
identifier (via a Random Number Generator, source port number,...)
that is common to all connections of a single test. It is used by
clients/servers to associate separate connections with a single
multi-connection test.
cmdRequest: A one-octet field set to CHSR_CREQ_SETUPREQ to indicate a
Setup request message. Note that CHSR_CREQ_NONE remains unused.
cmdResponse: A one-octet field. All Request PDUs always have a
Command Response of XXXX_CRSP_NONE.
maxBandwith: A two-octet field. A non-zero value of this field
specifies the maximum bit rate the client expects to send or receive
during the requested test in Mbps. The server compares this value to
its currently available configured limit for test admission control.
This field MAY be used for rate-limiting the maximum rate the server
should attempt. The maxBandwidth field's most significant bit, the
CHSR_USDIR_BIT, is set to 0 by default to indicate "downstream" and
has to be set to 1 to indicate "upstream".
testPort: A two-octet field, set to zero in the Test Setup Request
and populated by the server in the Test Setup Response. It contains
the UDP ephemeral port number on the server that the client has to
use for the Test Activation Request and subsequent Load or Status
PDUs.
modifierBitmap: A one-octet field. This document only assigns two
bits in this bitmap, see Section 11.3.3:
CHSR_JUMBO_STATUS This bit SHALL be set by default. By default,
sending rates up to 1 Gbps SHALL NOT produce IP packet sizes
greater than 1250 bytes (unless CHSR_TRADITIONAL_MTU is set) while
rates above 1 Gbps MAY produce IP packet sizes up to 9000 bytes.
When CHSR_JUMBO_STATUS is not set, all sending rates SHALL NOT
produce IP packet sizes greater than 1250 bytes (unless
CHSR_TRADITIONAL_MTU is set).
CHSR_TRADITIONAL_MTU This bit SHALL NOT be set by default. If set,
sending rates up to 1 Gbps MAY produce IP packets up to the
Traditional size of 1500 bytes. If CHSR_JUMBO_STATUS is
simultaneously not set, all sending rates SHALL NOT produce IP
packets greater than the Traditional size of 1500 bytes.
Other bit positions are left unassigned by this document.
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authMode: A one-octet field. The authMode field currently has two
values assigned (see Section 11.3.4). One of the following has to be
set (see Section 4.3 for requirements and details of operation):
AUTHMODE_1: Required Authentication for Control phase
AUTHMODE_2: Optional Authentication for Control and Data phase
(Status Feedback PDU only)
A range of 60 through 63 is reserved for experimentation. IANA is
asked to create a registry for the assigned values; see the IANA
Considerations Section.
authUnixTime: A 32-bit timestamp of the current system (wall-clock)
time since the Unix Epoch on January 1st, 1970 at 00:00:00 UTC.
authDigest: This field contains the 32-octet HMAC-SHA-256 hash that
covers the entire PDU. Normally, the calculation is done as the last
step of building the PDU. However, if the optional checkSum field is
being utilized, it becomes the penultimate step and is done just
prior to the checksum calculation (with the checkSum field set to
zero).
keyId: A one-octet field carrying localKeyName, the numeric key
identifier for a key in the shared key table.
reservedAuth1: A one-octet field. This field MUST be set to 0 and
MUST be ignored upon receipt. Consistent naming and placement of the
reservedAuth1 field across all PDUs is done to minimize
authentication related changes in future UDPSTP versions.
checkSum: A two-octet field, containing an optional checksum of the
entire PDU (see Section 4.6 for guidance). The calculation is done
as the very last step of building the PDU, with the checkSum field
set to zero.
5.2. Server Test Setup Request Processing and Response Generation
This section describes the processes at the server to evaluate the
Test Setup Request and determine the next steps. When the server
receives the Setup Request, it SHALL first perform the following:
Message Verification Procedure
1. Verify that the size of the message is correct.
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2. If the optional checkSum field is being utilized, validate the
checksum as described in Section 4.6 and (if valid) zero the
checkSum field prior to authentication verification.
3. Verify that the authMode value is valid and appropriate (per
Section 4.3) for the message type.
4. If the authMode is valid and appropriate, authenticate the
message by checking the authDigest as prescribed in Section 4.3.
5. If the message is authentic, check the authUnixTime field for
acceptable immediacy.
Note: If any of the above checks fail, the message SHALL be
considered invalid.
5.2.1. Test Setup Request Processing - Rejection
The server SHALL then evaluate the other fields in the protocol
header, such as the protocol version, the PDU ID (to validate the
type of message), the maximum Bandwidth requested for the test, and
the modifierBitmap for use of options such as Jumbo datagram status
and Traditional MTU (1500 bytes).
If the client has selected options for:
* Jumbo datagram support (modifierBitmap),
* Traditional MTU (modifierBitmap),
* Authentication mode (authMode)
that do not match the server configuration, the server MUST reject
the Setup Request.
If the Setup Request must be rejected, the conditions below determine
whether the server sends a response:
* If the authDigest is valid, a Test Setup Response SHALL be sent
back to the client with a corresponding command response value
indicating the reason for the rejection.
* If the authDigest is invalid, then the Test Setup Request SHOULD
fail silently. The exception is for operations support: server
administrators are permitted to send a Setup Response to support
operations and troubleshooting.
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The additional circumstances when a server SHALL NOT communicate the
appropriate Command Response code for an error condition (fail
silently) are when:
1. the Setup Request PDU size is not equal to the 'struct
controlHdrSR' size shown in Figure 3,
2. the PDU ID is not 0xACE1 (Test Setup PDU), or
3. a directed attack has been detected,
in which case the server will allow setup attempts to terminate
silently. Attack detection is beyond the scope of this
specification.
When the server replies to a Test Setup Request message, the Test
Setup Response PDU is structured identically to the Request PDU and
SHALL retain the original values received in it, with the following
exceptions:
* The cmdRequest field is set to CHSR_CREQ_SETUPRSP, indicating a
response.
* The cmdResponse field is set to an error code (starting at
cmdResponse 2, Bad Protocol Version, see Section 11.3.5),
indicating the reason for rejection. If cmdResponse indicates a
bad protocol version (CHSR_CRSP_BADVER), the protocolVer field is
also updated to indicate the current expected version.
* The authUnixTime field is updated to the current system (wall-
clock) time and, after the authDigest and checkSum fields are
zeroed, the authDigest is recalculated and inserted. If the
optional checkSum field is being utilized, it is then also
calculated and inserted.
The Setup Request/Response message PDU SHALL be organized as follows
(here and in all following code figures coded by programming language
C [C-Prog]):
<CODE BEGINS>
//
// Control header for UDP payload of Setup Request/Response PDUs
//
struct controlHdrSR {
#define CHSR_ID 0xACE1
uint16_t pduId; // PDU ID
#define PROTOCOL_VER 20
uint16_t protocolVer; // Protocol version
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uint8_t mcIndex; // Multi-connection index
uint8_t mcCount; // Multi-connection count
uint16_t mcIdent; // Multi-connection identifier
#define CHSR_CREQ_NONE 0
#define CHSR_CREQ_SETUPREQ 1 // Setup request
#define CHSR_CREQ_SETUPRSP 2 // Setup response
uint8_t cmdRequest; // Command request
#define CHSR_CRSP_NONE 0 // (used with request)
#define CHSR_CRSP_ACKOK 1 // Acknowledgment
#define CHSR_CRSP_BADVER 2 // Bad version
#define CHSR_CRSP_BADJS 3 // Jumbo setting mismatch
#define CHSR_CRSP_AUTHNC 4 // Auth. not configured
#define CHSR_CRSP_AUTHREQ 5 // Auth. required
#define CHSR_CRSP_AUTHINV 6 // Auth. (mode) invalid
#define CHSR_CRSP_AUTHFAIL 7 // Auth. failure
#define CHSR_CRSP_AUTHTIME 8 // Auth. time invalid
#define CHSR_CRSP_NOMAXBW 9 // Max bandwidth required
#define CHSR_CRSP_CAPEXC 10 // Capacity exceeded
#define CHSR_CRSP_BADTMTU 11 // Trad. MTU mismatch
#define CHSR_CRSP_MCINVPAR 12 // Multi-conn. invalid params
#define CHSR_CRSP_CONNFAIL 13 // Conn. allocation failure
uint8_t cmdResponse; // Command response
#define CHSR_USDIR_BIT 0x8000 // Upstream direction bit
uint16_t maxBandwidth; // Required bandwidth in Mbps
uint16_t testPort; // Test port on server
#define CHSR_JUMBO_STATUS 0x01
#define CHSR_TRADITIONAL_MTU 0x02
uint8_t modifierBitmap; // Modifier bitmap
// ========== Integrity Verification ==========
#define AUTHMODE_1 1 // Mode 1: Authenticated Control
#define AUTHMODE_2 2 // Mode 2: Authenticated Control+Status
uint8_t authMode; // Authentication mode
uint32_t authUnixTime; // Authentication timestamp
#define AUTH_DIGEST_LENGTH 32 // SHA-256 digest length
uint8_t authDigest[AUTH_DIGEST_LENGTH];
uint8_t keyId; // Key ID in shared table
uint8_t reservedAuth1; // (reserved for alignment)
uint16_t checkSum; // Header checksum
};
#define SHA256_KEY_LEN 32 // Authentication key length
<CODE ENDS>
Figure 3: Test Setup PDU
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5.2.2. Test Setup Request Processing - Acceptance
If the server finds that the Setup Request matches its configuration
and is otherwise acceptable, the server SHALL initiate a new
connection to receive the Test Activation Request from the client,
using a new UDP socket allocated from the UDP ephemeral port range.
This new socket will also be used for the subsequent Load and Status
PDUs that are part of testing (with the port number communicated back
to the client in testPort field of the Test Setup Response). Then,
the server SHALL start a watchdog timer (to terminate the new
connection if the client goes silent) and SHALL send the Test Setup
Response back to the client. The watchdog timer is set to the same
value as on the Client side (see Section 5)
When the server replies to the Test Setup Request message, the Test
Setup Response PDU is structured identically to the Request PDU and
SHALL retain the original values received in it, with the following
exceptions:
* The cmdRequest field is set to CHSR_CREQ_SETUPRSP, indicating a
response.
* The cmdResponse field is set to CHSR_CRSP_ACKOK, indicating an
acknowledgment.
* The testPort field is set to the ephemeral port number to be used
for the client's Test Activation Request and all subsequent
communication.
* The authUnixTime field is updated to the current system (wall-
clock) time and, after the authDigest and checkSum fields are
zeroed, the authDigest is recalculated and inserted. If the
optional checkSum field is being utilized, it is then also
calculated and inserted.
Finally, the new UDP connection associated with the new socket and
port are made ready, and the server awaits further communication
there.
To ensure that a server's local firewall will successfully allow
packets received for the new ephemeral port, the server SHALL
immediately send a Null Request with the corresponding values
including the source and destination IP addresses and port numbers.
The source port SHALL be the new ephemeral port. This operation
allows communication to the server even when the server's local
firewall prohibits open ranges of ephemeral ports. The packet is not
expected to arrive successfully at the client if the client-side
firewall blocks unexpected traffic. If the Null Request arrives at
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the client, it is a confirmation that further exchanges are possible
on the new port-pair (but this is not strictly necessary). If
received, the client SHALL follow the message verification procedure
listed in Section 5.2, Paragraph 2. Note that there is no response
to a Null Request.
The UDP PDU format layout SHALL be as follows (big-endian AB):
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| pduId | protocolVer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| cmdRequest | cmdResponse | reserved1 | authMode |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| authUnixTime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. authDigest (32-octet) .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| keyId | reservedAuth1 | checkSum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Null Request PDU Layout
Authentication and checksum fields follow the same methodology as
with the Setup Request and Response.
Additional details regarding the Null Request fields are as follows:
pduId: IANA is asked to assign the value hex 0xDEAD (Section 11.3.1).
cmdRequest: Is set to CHNR_CREQ_NULLREQ indicating a Null Request
message.
cmdResponse: Is set to CHNR_CRSP_NONE.
authMode: Same as Section 5.1
authUnixTime: Same as Section 5.1
authDigest: Same as Section 5.1
keyId: Same as Section 5.1
reservedAuth1: Same as Section 5.1
checkSum: Same as Section 5.1
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If a Test Activation Request is not subsequently received from the
client on the new ephemeral port number before the watchdog timer
expires, the server SHALL close the socket and deallocate the
associated resources.
The Null Request message PDU SHALL be organized as follows:
<CODE BEGINS>
//
// Control header for UDP payload of Null Request PDU
//
struct controlHdrNR {
#define CHNR_ID 0xDEAD
uint16_t pduId; // PDU ID
uint16_t protocolVer; // Protocol version
#define CHNR_CREQ_NONE 0
#define CHNR_CREQ_NULLREQ 1 // Null request
uint8_t cmdRequest; // Command request
#define CHNR_CRSP_NONE 0 // (used with request)
uint8_t cmdResponse; // Command response
uint8_t reserved1; // (reserved for alignment)
// ========== Integrity Verification ==========
uint8_t authMode; // Authentication mode
uint32_t authUnixTime; // Authentication timestamp
uint8_t authDigest[AUTH_DIGEST_LENGTH];
uint8_t keyId; // Key ID in shared table
uint8_t reservedAuth1; // (reserved for alignment)
uint16_t checkSum; // Header checksum
};
<CODE ENDS>
Figure 5: Null Request PDU
5.3. Setup Response Processing at the Client
When the client receives the Test Setup Response message, it SHALL
first follow the Message Verification Procedure listed in
Section 5.2, Paragraph 2.
It SHALL then proceed to evaluate the other fields in the protocol,
beginning with the protocol version, PDU ID (to validate the type of
message), and cmdRequest for the role of the message, which MUST be
Test Setup Response, CHSR_CREQ_SETUPRSP, as indicated by Figure 3.
If the cmdResponse value indicates an error (values greater than
CHSR_CRSP_ACKOK) the client SHALL display/report a relevant message
to the user or management process and exit. If the client receives a
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Command Response code that is not equal to one of the codes defined,
the client MUST terminate the connection and terminate operation of
the current Setup Request. If the Command Server Response code value
indicates success (CHSR_CRSP_ACKOK), the client SHALL compose a Test
Activation Request with all the test parameters it desires, such as
the test direction, the test duration, etc., as described below.
6. Test Activation Request and Response
This section is divided according to the sending and processing of
the client, server, and again at the client.
6.1. Client Generates Test Activation Request
Upon a successful setup exchange, the client SHALL compose and send
the Test Activation Request to the UDP port number the server
communicated in the Test Setup Response (the new ephemeral port, and
not the standard UDPSTP port).
The UDP PDU format layout is as follows (big-endian AB):
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| txInterval1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| udpPayload1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| burstSize1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| txInterval2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| udpPayload2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| burstSize2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| udpAddon2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| pduId | protocolVer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| cmdRequest | cmdResponse | lowThresh |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| upperThresh | trialInt |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| testIntTime | reserved1 | dscpEcn |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| srIndexConf | useOwDelVar |highSpeedDelta |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| slowAdjThresh | seqErrThresh |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ignoreOooDup |modifierBitmap | rateAdjAlgo | reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. srStruct (28 octets) .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| subIntPeriod | reserved3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| reserved4 | reserved5 | authMode |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| authUnixTime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. authDigest (32-octet) .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| keyId | reservedAuth1 | checkSum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 6: Test Activation PDU Layout
Fields are populated based on default values or command-line options.
Authentication and checksum fields follow the same methodology as
with the Setup Request and Response.
pduId: IANA is asked to assign the value hex 0xACE2 (Section 11.3.1).
cmdRequest: Is set to CHTA_CREQ_TESTACTUS to indicate an upstream
test activation or alternatively to CHTA_CREQ_TESTACTDS to indicate a
downstream test activation. Note that CHTA_CREQ_NONE remains unused.
See Section 11.3.6.
cmdResponse: three CHTA_CRSP_<Indication> values are defined, see
Figure 7.
lowThresh: Two two-octet field, low threshold Low on the Range of
Round Trip Time variation, RTT (Range is values above minimum RTT,
see also Table 3 [TR-471].
upperThresh: Two two-octet field, upper threshold Low on the Range of
Round Trip Time variation, RTT (Range is values above minimum RTT,
see also Table 3 of [TR-471].
trialInt: A two-octet field, indicating the Status Feedback / trial
interval [ms]. The test interval Delta_t is subdivided into a number
of sub-intervals dt, and each sub-interval is further divided into a
number of trial intervals (see [TR-471]). Starts by 1 and is
continuously incremented during a single test interval (testIntTime).
testIntTime: A two-octet field. Duration of the test (either
downlink or uplink) with search algorithm in use, which serves as the
maximum duration of the search process in Seconds (see also
TestInterval, Table 3 of [TR-471].
dscpEcn: Diffserv code point and ECN field, see also the DSCP field
specified by [TR-471]. This specification does not provide an ECN-
capable transport, therefore the sender SHALL set the ECN field to
not_ECT.
srIndexConf: A two-octet field. The requested Configured Sending
Rate Table index, used in a Test Activation Request, of the desired
fixed or starting sending rate (depending on whether
CHTA_SRIDX_ISSTART is cleared or set respectively). Because a value
of zero is a valid fixed or starting sending rate index, the field
SHALL be set to its maximum (CHTA_SRIDX_DEF) when requesting the
default behavior of the server (starting the selected load rate
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adjustment algorithm at its minimum/zero index). This SHALL be
equivalent to setting srIndexConf to zero and setting the
CHTA_SRIDX_ISSTART bit.
useOwDelVar: A one-octet field. Boolean, default True (False: Use
RTT=round-trip delay variation in the load rate adjustment
algorithm)(True: EnableIPDV which uses one-way delay variation for
the load rate adjustment algorithm), see EnableIPDV in Table 1 of
[TR-471].
highSpeedDelta: A one-octet field, see Appendix A of [RFC9097].
slowAdjThresh, seqErrThresh: Two two-octet fields, see Appendix A of
[RFC9097].
ignoreOooDup: A one-octet field. Ignore out of oder duplicates,
Boolean. When True only Loss counts toward received packet sequence
number errors. When False, Loss, Reordering and Duplication are all
counted as sequence number errors, default True (see also Table 3 of
[TR-471]).
modifierBitmap: A one-octet field. This document only assigns two
bits in this bitmap, see Section 11.3.7:
CHTA_SRIDX_ISSTART Treat srIndexConf as the starting sending rate to
be used by the load rate adjustment algorithm
CHTA_RAND_PAYLOAD Randomize the Payload Content beyond the Load PDU
header
Other bit positions are left unassigned by this document.
rateAdjAlgo: A one-octet field. The applied Load Rate Adjustment
Algorithm, see Section 11.3.8.
Sending Rate structure (srStruct), used by the server in a Test
Activation Response for an upstream test, to communicate the
(initial) Load PDU transmission parameters the client SHALL use. For
a Test Activation Request or a downstream test, this structure SHALL
be zeroed. Two sets of periodic transmission parameters are
available, allowing for dual independent transmitters (to support a
high degree of rate granularity). The fields are defined as follows:
txInterval1 and txInterval2: Two four-octet fields indicating the
load rate transmit interval in [us]. A 100 us granularity is
recommended for optimal rate selection.
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udpPayload1 and udpPayload2: Two four-octet fields indicating the UDP
payload at load rate in [byte].
burstSize1 and burstSize2: Two four-octet fields indicating the burst
size at load rate by a dimensionless number (of datagrams).
udpAddon2: A four-octet field indicating the size of a single Load
PDU to be sent at the end of the txInterval2 send sequence, even when
udpPayload2 or burstSize2 are zero and result in no transmission of
their own.
subIntPeriod: A two-octet field. Test Sub-interval period in [ms],
(see also Table 3 of [TR-471]). Trials with subIntPeriod in a range
of 100 to 10000 [ms] resulted in a default value of 1000 ms.
authMode: Same as Section 5.1
authUnixTime: Same as Section 5.1
authDigest: Same as Section 5.1
keyId: Same as Section 5.1
reservedAuth1: Same as Section 5.1
checkSum: Same as Section 5.1
The Test Activation Request/Response message PDU (as well as the
included Sending Rate structure) SHALL be organized as follows:
<CODE BEGINS>
//
// Sending rate structure for a single row of transmission parameters
//
struct sendingRate {
uint32_t txInterval1; // Transmit interval (us)
uint32_t udpPayload1; // UDP payload (bytes)
uint32_t burstSize1; // UDP burst size per interval
uint32_t txInterval2; // Transmit interval (us)
uint32_t udpPayload2; // UDP payload (bytes)
uint32_t burstSize2; // UDP burst size per interval
uint32_t udpAddon2; // UDP add-on (bytes)
};
//
// Control header for UDP payload of Test Act. Request/Response PDUs
//
struct controlHdrTA {
#define CHTA_ID 0xACE2
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uint16_t pduId; // PDU ID
uint16_t protocolVer; // Protocol version
#define CHTA_CREQ_NONE 0
#define CHTA_CREQ_TESTACTUS 1 // Test activation upstream
#define CHTA_CREQ_TESTACTDS 2 // Test activation downstream
uint8_t cmdRequest; // Command request
#define CHTA_CRSP_NONE 0 // (used with request)
#define CHTA_CRSP_ACKOK 1 // Acknowledgment
#define CHTA_CRSP_BADPARAM 2 // Bad/invalid test params
uint8_t cmdResponse; // Command response
uint16_t lowThresh; // Low delay variation threshold (ms)
uint16_t upperThresh; // Upper delay variation threshold (ms)
uint16_t trialInt; // Status Feedback/trial interval (ms)
uint16_t testIntTime; // Test interval time (sec)
uint8_t reserved1; // (reserved for alignment)
uint8_t dscpEcn; // DiffServ and ECN field for testing
#define CHTA_SRIDX_DEF UINT16_MAX // Request default server search
uint16_t srIndexConf; // Configured Sending Rate Table index
uint8_t useOwDelVar; // Use one-way delay, not RTT (BOOL)
uint8_t highSpeedDelta; // High-speed row adjustment delta
uint16_t slowAdjThresh; // Slow rate adjustment threshold
uint16_t seqErrThresh; // Sequence error threshold
uint8_t ignoreOooDup; // Ignore Out-of-Order/Dup (BOOL)
#define CHTA_SRIDX_ISSTART 0x01 // Use srIndexConf as starting index
#define CHTA_RAND_PAYLOAD 0x02 // Randomize payload
uint8_t modifierBitmap; // Modifier bitmap
#define CHTA_RA_ALGO_B 0 // Algorithm B
#define CHTA_RA_ALGO_C 1 // Algorithm C
uint8_t rateAdjAlgo; // Rate adjust. algorithm
uint8_t reserved2; // (reserved for alignment)
struct sendingRate srStruct; // Sending rate structure
uint16_t subIntPeriod; // Sub-interval period (ms)
uint16_t reserved3; // (reserved for alignment)
uint16_t reserved4; // (reserved for alignment)
uint8_t reserved5; // (reserved for alignment)
// ========== Integrity Verification ==========
uint8_t authMode; // Authentication mode
uint32_t authUnixTime; // Authentication timestamp
uint8_t authDigest[AUTH_DIGEST_LENGTH];
uint8_t keyId; // Key ID in shared table
uint8_t reservedAuth1; // (reserved for alignment)
uint16_t checkSum; // Header checksum
};
<CODE ENDS>
Figure 7: Test Activation PDU
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6.2. Server Processes Test Activation Request and Generates Response
After the server receives the Test Activation Request on the new
connection, it chooses to accept, ignore or modify any of the test
parameters. When the server replies to the Test Activation Request
message, the Test Activation Response PDU is structured identically
to the Request PDU and SHALL retain the original values received in
it unless they are explicitly coerced to a server acceptable value.
When the server receives the Test Activation Request message, it
SHALL first follow the Message Verification Procedure listed in
Section 5.2, Paragraph 2.
6.2.1. Server Rejects or Modifies Request
When evaluating the Test Activation Request, the server MAY allow the
client to specify its own fixed or starting send rate via
srIndexConf.
Alternatively, the server MAY enforce a maximum limit of the fixed or
starting send rate which the client can successfully request. If the
client's Test Activation Request exceeds the server's configured
maximum, the server MUST either reject the request or coerce the
value to the configured maximum bit rate, and communicate that
maximum to the client in the Test Activation Response. The client
can of course choose to end the test, as appropriate.
Other parameters where the server has the OPTION to coerce the client
to use values other than those in the Test Activation Request are
(grouped by role):
* Load rate adjustment algorithm: lowThresh, upperThresh,
useOwDelayVar, highSpeedDelta, slowAdjThresh, seqErrThresh,
highSpeedDelta, ignoreOooDup, rateAdjAlgo.
* Test duration/intervals: trialInt, testIntTime, subIntPeriod
* Packet marking: dscpEcn
Coercion is a step towards performing a test with the server-
configured values; even though the client might prefer certain
values, the server gives the client an opportunity to run a test with
different values than the preferred set. In these cases, the Command
Response value SHALL be CHTA_CRSP_ACKOK.
Note that the server also has the option of completely rejecting the
request and sending back an appropriate cmdResponse field value
(currently only CHTA_CRSP_BADPARAM, see Section 11.3.9).
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Whether this error response is sent or not depends on the Security
mode of operation and the outcome of authDigest validation.
If the Test Activation Request must be rejected (due to the Command
Response value being CHTA_CRSP_BADPARAM), and
* If the authDigest is valid, a Test Activation Response SHALL be
sent back to the client with a corresponding command response
value indicating the reason for the rejection.
* If the authDigest is invalid, then the Test Activation Request
SHOULD fail silently. The exception is for operations support:
server administrators are permitted to send a Activation Response
to support operations and troubleshooting.
The additional circumstances when a server SHALL NOT communicate the
appropriate Command Response code for an error condition (fail
silently) are when:
1. the Test Activation Request PDU size is not equal to the 'struct
controlHdrTA' size shown in Figure 7,
2. the PDU ID is not 0xACE2 (Test Activation PDU), or
3. a directed attack has been detected,
in which case the server will allow Test Activation Requests to
terminate silently. Attack detection is beyond the scope of this
specification.
6.2.2. Server Accepts Request and Generates Response
When the server sends the Test Activation Response, it SHALL set the
cmdResponse field to CHTA_CRSP_ACKOK (see Section 11.3.9)
If the client has requested an upstream test, the server SHALL:
* include the transmission parameters from the first row of the
Sending Rate Table in the Sending Rate structure (if requested by
srIndexConf having been set to CHTA_SRIDX_DEF), or
* include the transmission parameters from the designated Configured
Sending Rate Table index (srIndexConf) of the Sending Rate
Table where, if CHTA_SRIDX_ISSTART is set in modifierBitmap, this
will be used as the starting rate for the load rate adjustment
algorithm, else it will be considered a fixed-rate test.
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When generating the Test Activation Response (acceptance) for a
downstream test, the server SHALL set all octets of the Sending Rate
structure to zero.
If activation continues, the server prepares the new connection for
an upstream OR downstream test.
In the case of an upstream test, the server SHALL prepare to use a
single timer to send Status PDUs at the specified interval. For a
downstream test, the server SHALL prepare to utilize dual timers to
send Load PDUs based on
* the transmission parameters directly from the first row of the
Sending Rate Table (if requested by srIndexConf having been set to
CHTA_SRIDX_DEF), or
* the transmission parameters from the designated Configured Sending
Rate Table index (srIndexConf) of the Sending Rate Table where, if
CHTA_SRIDX_ISSTART is set in modifierBitmap, this will be used as
the starting rate for the load rate adjustment algorithm, else it
will be considered a fixed-rate test.
The server SHALL then send the Test Activation Response back to the
client, update the watchdog timer with a new timeout value, and set a
test duration timer to eventually stop the test.
6.3. Client Processes Test Activation Response
When the client receives the Test Activation Response message, it
SHALL first follow the Message Verification Procedure listed in
Section 5.2, Paragraph 2.
After the client receives the (vetted) Test Activation Response, it
first checks the command response value.
If the client receives a Test Activation cmdResponse field value that
indicates an error, the client SHALL display/report a relevant
message to the user or management process and exit.
If the client receives a Test Activation cmdResponse field value that
is not equal to one of the codes defined in Section 11.3.9, the
client MUST terminate the connection and terminate operation of the
current setup procedure.
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If the client receives a Test Activation Command Response value that
indicates success (CHTA_CRSP_ACKOK, see Section 11.3.9), the client
SHALL update its configuration to use any test parameters modified by
the server. If the setup parameters coerced by the server are not
acceptable to the client, the client ends the test.
To finalize an accepted test activation, the client SHALL prepare its
connection for either an upstream test with dual timers set to send
Load PDUs (based on the starting transmission parameters sent by the
server), OR a downstream test with a single timer to send Status PDUs
at the specified interval.
Then, the client SHALL stop the test initiation timer and start a
watchdog timer to detect if the server goes quiet.
The connection is now ready for testing.
7. Test Load Stream Transmission and Measurement Status Feedback
Messages
This section describes the data phase of the protocol. The roles of
sender and receiver vary depending on whether the direction of
testing is from server to client, or the reverse.
7.1. Load PDU and Roles
Testing proceeds with one endpoint sending Load PDUs, based on
transmission parameters from the Sending Rate Table, and the other
endpoint sending Status Feedback messages to communicate the traffic
conditions at the receiver. When the server is sending Status
Feedback messages, they will also contain the latest transmission
parameters from the Sending Rate Table that the client SHALL use.
When a Load PDU is received, the receiver SHALL first:
1. Verify that the size of the message is greater than or equal to
the 'struct loadHdr' size shown in Figure 9.
2. If the optional checkSum field is being utilized, validate the
checksum for the Load PDU header portion of the total message (as
described in Section 4.6).
3. Confirm that the PDU ID is 0xBEEF (Load PDU).
Note: If any of the above checks fail, the message SHALL be
considered invalid.
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The watchdog timer at the receiver SHALL be reset each time a valid
Load PDU is received (which includes verification of the checkSum, if
in use). See non-graceful test stop in Section 8 for handling the
watchdog timeout expiration at each endpoint. Note that the watchdog
timer's purpose is to detect a connection failure or a massive
congestion condition only.
When the server is sending Load PDUs in the role of sender, it SHALL
use the transmission parameters directly from the Sending Rate
Table via the index that is currently selected (which was indirectly
based on the feedback in its received Status Feedback messages).
However, when the client is sending Load PDUs in the role of sender,
it SHALL use the discreet transmission parameters that were
communicated by the server in its periodic Status Feedback messages
(and not referencing a Sending Rate Table directly). This approach
allows the server to control the individual sending rates as well as
the algorithm used to decide when and how to adjust the rate.
The server uses a load rate adjustment algorithm which evaluates
measurements taken locally at the Load PDU receiver. When the client
is the receiver, the information is communicated to the server via
the periodic Status Feedback messages. When the server is the
receiver, the information is used directly (although it is also
communicated to the client via its periodic Status Feedback
messages). This approach is unique to this protocol; it provides the
ability to search for the Maximum IP Capacity and specify specific
sender behaviors that are absent from other testing tools. Although
the algorithm depends on the protocol, it is not part of the protocol
per se.
The default algorithm (B, see [Y.1540]) has three paths to its
decision on the next sending rate:
1. When there are no impairments present (no sequence errors and low
delay variation), resulting in a sending rate increase.
2. When there are low impairments present (no sequence errors but
higher levels of delay variation), the same sending rate is
maintained.
3. When the impairment levels are above the thresholds set for this
purpose and "congestion" is inferred, resulting in a sending rate
decrease.
Algorithm B also has two modes for increasing/decreasing the sending
rate:
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* A high-speed mode (fast) to achieve high sending rates quickly,
but also back-off quickly when "congestion" is inferred from the
measurements. Consecutive feedback intervals that have a supra-
threshold count of sequence number anomalies and/or contain an
upper delay variation threshold exception in all of the
consecutive intervals are sufficient to declare "congestion"
within a test. The threshold of consecutive feedback intervals
SHALL be configurable with a default of 3 intervals.
* A single-step (slow) mode where all rate adjustments use the
minimum increase or decrease of one step in the sending rate
table. The single step mode continues after the first inference
of "congestion" from measured impairments.
An OPTIONAL load rate adjustment algorithm (designated C) has been
defined in [TR-471]. Algorithm C operation and modes are similar to
B, but C uses multiplicative increases in the fast mode to reach the
Gigabit range quickly and adds the possibility to re-try the fast
mode during a test (which improves the measurement accuracy in
dynamic or error-prone access, such as radio access).
On the other hand, the test configuration MAY use a fixed sending
rate requested by the client, using the field srIndexConf.
The client MAY communicate the desired fixed-rate in its test
activation request.
The UDP PDU format layout SHALL be as follows (big-endian AB):
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| pduId | testAction | rxStopped |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| lpduSeqNo |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| udpPayload | spduSeqErr |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| spduTime_sec |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| spduTime_nsec |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| lpduTime_sec |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| lpduTime_nsec |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rttRespDelay | checkSum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. Payload Content... .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: Load PDU Layout
Specific details regarding Load PDU fields are as follows:
pduId: IANA is asked to assign the value hex 0xBEEF (Section 11.3.1).
testAction: A one-octet fileld designating the current test action as
either TEST_ACT_TEST (testing in progress), TEST_ACT_STOP1 (first
phase of graceful termination, used locally by server), or
TEST_ACT_STOP2 (second phase of graceful termination, sent by server
and reciprocated by client). See Section 8 for additional
information on test termination.
rxStopped: A one-octet fileld. Boolean, 0 or 1, used to indicate to
the remote endpoint that local receive traffic (either Load or Status
PDUs) has stopped. All outgoing Load or Status PDUs SHALL continue
to assert this indication until traffic is received again, or the
test is terminated. The time threshold to trigger this condition is
expected to be a reasonable fraction of the watchdog timeout (a
default of one second is recommended).
lpduSeqNo: A four-octet field indicating the Load PDU sequence number
(starting at 1). Used to determine loss, out-of-order, and
duplicates.
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udpPayload: A two-octet field indicating the total payload size of
the UDP datagram including the Load PDU message header and Payload
Content (i.e., what the UDP socket read function would return). This
field allows the Load PDU receiver to maintain accurate receive
statistics if utilizing receive truncation (only requesting the Load
PDU message header octets from the protocol stack).
spduSeqErr: A two-octet field indicating the Status PDU loss count,
as seen by the Load PDU sender. This is determined by the Status PDU
sequence number (spduSeqNo) in the most recently received Status PDU.
Used to communicate to the Load PDU receiver that return traffic (in
the unloaded direction) is being lost.
spduTime_sec/spduTime_nsec: Two four-octet fields containing a copy
of the most recent spduTime_sec/spduTime_nsec from the last Status
PDU received. Used for RTT measurements made by the Load PDU
receiver.
lpduTime_sec/lpduTime_nsec: Two four-octet fields containing the
local send time of the Load PDU. Used for one-way delay variation
measurements made by the Load PDU receiver.
rttRespDelay: A two-octet field indicating the RTT response delay,
used to "adjust" raw RTT. On the Load PDU sender, it is the number
of milliseconds from reception of the most recent Status PDU (when
the latest spduTime_sec/spduTime_nsec was obtained) to the
transmission of the Load PDU (where the previously obtained
spduTime_sec/spduTime_nsec is returned). When the Load PDU receiver
is calculating RTT, by subtracting the copied Status PDU send time
(in the Load PDU) from the local Load PDU receive time, this value is
subtracted from the raw RTT to correct for any response delay due to
Load PDU scheduling.
checkSum: An optional checksum of only the Load PDU header (see
Section 4.6 for guidance). The checksum does not cover the Payload
Content. The calculation is done as the very last step of building
the PDU header, with the checksum field set to zero.
Payload Content: All zeroes, all ones, or a pseudorandom binary
sequence.
The Load PDU SHALL be organized as follows (followed by any payload
content):
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<CODE BEGINS>
//
// Load header for UDP payload of Load PDUs
//
struct loadHdr {
#define LOAD_ID 0xBEEF
uint16_t pduId; // PDU ID
#define TEST_ACT_TEST 0 // Test active
#define TEST_ACT_STOP1 1 // Stop indication used locally by server
#define TEST_ACT_STOP2 2 // Stop indication exchanged with client
uint8_t testAction; // Test action
uint8_t rxStopped; // Receive traffic stopped (BOOL)
uint32_t lpduSeqNo; // Load PDU sequence number
uint16_t udpPayload; // UDP payload (bytes)
uint16_t spduSeqErr; // Status PDU sequence error count
uint32_t spduTime_sec; // Send time in last rx'd status PDU
uint32_t spduTime_nsec; // Send time in last rx'd status PDU
uint32_t lpduTime_sec; // Send time of this load PDU
uint32_t lpduTime_nsec; // Send time of this load PDU
uint16_t rttRespDelay; // Response delay for RTT (ms)
uint16_t checkSum; // Header checksum
};
<CODE ENDS>
Figure 9: Load PDU
7.2. Status PDU
The Load PDU receiver SHALL send a Status PDU to the sender during a
test at the configured feedback interval, after at least one Load PDU
has been received (when there is something to provide status on). In
test scenarios with long delays between client and server, it is
possible for the Status PDU send timer to fire before the first Load
PDU arrives. In these cases, the Status PDU SHALL NOT be sent.
When the Load PDU sender receives a Status PDU message, it SHALL
first follow the Message Verification Procedure listed in
Section 5.2, Paragraph 2.
The watchdog timer at the Load PDU sender SHALL be reset each time a
valid Status PDU is received (which includes verification of the
checkSum and/or authDigest, if in use). See non-graceful test stop
in Section 8 for handling the watchdog timeout expiration at each
endpoint.
The UDP PDU format layout SHALL be as follows (big-endian AB):
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rxDatagrams |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rxBytes |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| deltaTime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| seqErrLoss |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| seqErrOoo |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| seqErrDup |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| delayVarMin |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| delayVarMax |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| delayVarSum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| delayVarCnt |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rttVarMinimum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rttVarMaximum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| accumTime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| pduId | testAction | rxStopped |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| spduSeqNo |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. srStruct (28 octets) .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| subIntSeqNo |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. sisSav (56 octets) .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| seqErrLoss |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| seqErrOoo |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| seqErrDup |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| clockDeltaMin |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| delayVarMin |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| delayVarMax |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| delayVarSum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| delayVarCnt |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rttMinimum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rttVarSample |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| delayMinUpd | reserved1 | reserved2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| tiDeltaTime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| tiRxDatagrams |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| tiRxBytes |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| spduTime_sec |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| spduTime_nsec |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| reserved3 | reserved4 | authMode |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| authUnixTime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. authDigest (32-octet) .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| keyId | reservedAuth1 | checkSum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: Status PDU Layout
Note that the Sending Rate structure is defined in Section 6.
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The primary role of the Status Feedback message is to communicate to
the Load PDU sender the traffic conditions at the Load PDU receiver.
While the Sub-Interval Statistics structure (sisSav) covers the most
recently saved (completed) sub-interval, similar fields directly in
the Status PDU itself cover the most recent trial interval (the time
period between Status Feedback messages, completed by this Status
PDU). Both sets of statistics SHALL always be populated by the Load
PDU receiver, regardless of role (client or server).
Details on the Status PDU measurement fields are provided in
[RFC9097]. Authentication and checksum fields follow the same
methodology as with the Setup Request and Response. Additional
information regarding fields not defined previously are as follows:
pduId: IANA is asked to assign the value hex 0xFEED (Section 11.3.1).
spduSeqNo: A four-octet field containing the Status PDU sequence
number (starting at 1). Used by the Load PDU sender to detect Status
PDU loss (in the unloaded direction). The loss count is communicated
back to the Load PDU receiver via spduSeqErr in subsequent Load PDUs.
subIntSeqNo: A four-octet field containing the Sub-interval sequence
number (starting at 1) that corresponds to the statistics provided in
sisSav, for the last saved (completed) sub-interval.
sisSav: Sub-interval statistics saved (completed) for the most recent
sub-interval (as designated by the subIntSeqNo). These consist of
the following fields:
rxDatagrams: A four-octet field Sub-interval indicating the number of
received datagrams during the Sub-Interval.
rxBytes: An eight-octet field indicating the Sub-Interval byte count
(eight octets chosen to prevent overflow at high speeds).
deltaTime: A four-octet field indicating the exact duration of the
Sub-Interval in microseconds. Used to calculate the received traffic
rate together with rxBytes.
seqErrLoss/seqErrOoo/seqErrDup: Three four-octet fields, populated by
the Loss, out-of-order, and duplicate totals. Available for both the
sub-interval and trial interval, it is a breakout of the SeqErrors
count in Table 3 of [TR-471]. seqErrOoo and seqErrDup are realized by
comparing sequence numbers. A lookback list of the last n sequence
numbers received is used as the basis. Each Load PDU sequence number
is checked against this lookback. The number n may depend on the
implementation and on typical characteristics of environments, where
UDPST is deployed (like mobile networks or Wi-Fi). Currently, a
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default sequence number interval of n=32 has been chosen.
Specifically for seqErrOoo, each successively received higher seqno
sets the next-expected-seqno to seqno+1 and anything below that is
considered out-of-order (i.e., delayed). For example, given the
sequence 93, 94, 95, 100, 96, 97, 101, 98, 99, 102, 103, ...
reception of 96, 97, 98, and 99 would not increment the next-
expected-seqno and would all be considered out-of-order.
delayVarMin/delayVarMax/delayVarSum/delayVarCnt: Four four-octet
fields populated by the one-way delay variation measurements of all
received Load PDUs (where avg = sum/cnt). For each Load PDU
received, the send time (lpduTime_sec/lpduTime_nsec) is subtracted
from the local receive time, which is then normalized by subtracting
the current clockDeltaMin. Available for both the sub-interval and
trial interval.
rttVarMinimum/rttVarMaximum (in sisSav): Two four-octet fields
populated by the minimum and maximum RTT delay variation
(rttVarSample) in the sub-interval designated by the subIntSeqNo.
accumTime: The accumulated time of the test in milliseconds, based on
the duration of each sub-interval. Equivalent to the sum of each
deltaTime (although in ms) sent in each Status PDU during the test.
clockDeltaMin: A four-octet field indicating the minimum clock delta
(difference) since the beginning of the test. Obtained by
subtracting the send time of each Load PDU (lpduTime_sec/
lpduTime_nsec) from the local time that it was received. This value
is initialized with the first Load PDU received and is updated with
each subsequent one to maintain a current (and continuously updated)
minimum. If the endpoint clocks are sufficiently synchronized, this
will be the minimum one-way delay in milliseconds. Otherwise, this
value may be negative, but still valid for one-way delay variation
measurements for the default test duration (default is 10 [s]). If
the test duration is extended to a range of minutes, where
significant clock drift can occur, synchronized (or at least well-
disciplined) clocks may be required.
rttMinimum (in Status PDU): A four-octet field indicating the minimum
"adjusted" RTT measured since the beginning of the test. See
rttRespDelay regarding "adjusted" measurements. RTT is obtained by
subtracting the copied spduTime_sec/spduTime_nsec in the received
Load PDU from the local time at which it was received. This minimum
SHALL be kept current (and continuously updated) via each Load PDU
received with an updated spduTime_sec/spduTime_nsec. This value MUST
be positive. Before an initial value can be established, and because
zero is itself valid, it SHALL be set to STATUS_NODEL when
communicated in the Status PDU.
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rttVarSample: A four-octet field indicating the most recent
"adjusted" RTT delay variation measurement. See rttRespDelay
regarding "adjusted" measurements. RTT delay variation is obtained
by subtracting the current (and continuously updated) "adjusted" RTT
minimum, communicated as rttMinimum (in Status PDU), from each
"adjusted" RTT measurement (which is itself obtained by subtracting
the copied spduTime_sec/spduTime_nsec in the received Load PDU from
the local time at which it was received). Note that while one-way
delay variation is measured for every Load PDU received, RTT delay
variation is only sampled via the Status PDU sent and the very next
Load PDU received with the corresponding updated spduTime_sec/
spduTime_nsec. When a new value is unavailable (possibly due to
packet loss), and because zero is itself valid, it SHALL be set to
STATUS_NODEL when communicated in the Status PDU.
delayMinUpd: A one-octet field. Boolean, 0 or 1, indicating that the
clockDeltaMin and/or rttMinimum (in Status PDU), as measured by the
Load PDU receiver, has been updated.
tiDeltaTime/tiRxDatagrams/tiRxBytes: Three four-octet fields,
populated by the trial interval time in microseconds, along with the
received datagram and byte counts. Used to calculate the received
traffic rate for the trial interval.
spduTime_sec/spduTime_nsec: Two four-octet fields, containing the
local transmit time of the Status PDU. Expected to be copied into
spduTime_sec/spduTime_nsec in subsequent Load PDUs after being
received by the Load PDU sender. Used for RTT measurements.
authMode: Same as Section 5.1
authUnixTime: Same as Section 5.1
authDigest: Same as Section 5.1
keyId: Same as Section 5.1
reservedAuth1: Same as Section 5.1
checkSum: Same as Section 5.1
The Status Feedback message PDU (as well as the included Sub-Interval
Statistics structure) SHALL be organized as follows:
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<CODE BEGINS>
//
// Sub-interval statistics structure for received traffic information
//
struct subIntStats {
uint32_t rxDatagrams; // Received datagrams
uint64_t rxBytes; // Received bytes (64 bits)
uint32_t deltaTime; // Time delta (us)
uint32_t seqErrLoss; // Loss sum
uint32_t seqErrOoo; // Out-of-Order sum
uint32_t seqErrDup; // Duplicate sum
uint32_t delayVarMin; // Delay variation minimum (ms)
uint32_t delayVarMax; // Delay variation maximum (ms)
uint32_t delayVarSum; // Delay variation sum (ms)
uint32_t delayVarCnt; // Delay variation count
uint32_t rttMinimum; // Minimum round-trip time (ms)
uint32_t rttMaximum; // Maximum round-trip time (ms)
uint32_t accumTime; // Accumulated time (ms)
};
//
// Status feedback header for UDP payload of status PDUs
//
struct statusHdr {
#define STATUS_ID 0xFEED
uint16_t pduId; // PDU ID
uint8_t testAction; // Test action
uint8_t rxStopped; // Receive traffic stopped (BOOL)
uint32_t spduSeqNo; // Status PDU sequence number
struct sendingRate srStruct; // Sending rate structure
uint32_t subIntSeqNo; // Sub-interval sequence number
struct subIntStats sisSav; // Sub-interval saved stats
uint32_t seqErrLoss; // Loss sum
uint32_t seqErrOoo; // Out-of-Order sum
uint32_t seqErrDup; // Duplicate sum
uint32_t clockDeltaMin; // Clock delta minimum (ms)
uint32_t delayVarMin; // Delay variation minimum (ms)
uint32_t delayVarMax; // Delay variation maximum (ms)
uint32_t delayVarSum; // Delay variation sum (ms)
uint32_t delayVarCnt; // Delay variation count
#define STATUS_NODEL UINT32_MAX // No delay data/value
uint32_t rttMinimum; // Min round-trip time sampled (ms)
uint32_t rttVarSample; // Last round-trip time sample (ms)
uint8_t delayMinUpd; // Delay minimum(s) updated (BOOL)
uint8_t reserved1; // (reserved for alignment)
uint16_t reserved2; // (reserved for alignment)
uint32_t tiDeltaTime; // Trial interval delta time (us)
uint32_t tiRxDatagrams; // Trial interval receive datagrams
uint32_t tiRxBytes; // Trial interval receive bytes
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uint32_t spduTime_sec; // Send time of this status PDU
uint32_t spduTime_nsec; // Send time of this status PDU
uint16_t reserved3; // (reserved for alignment)
uint8_t reserved4; // (reserved for alignment)
// ========== Integrity Verification ==========
uint8_t authMode; // Authentication mode
uint32_t authUnixTime; // Authentication timestamp
uint8_t authDigest[AUTH_DIGEST_LENGTH];
uint8_t keyId; // Key ID in shared table
uint8_t reservedAuth1; // (reserved for alignment)
uint16_t checkSum; // Header checksum
};
<CODE ENDS>
Figure 11: Status PDU
8. Stopping a Test
When the test duration timer (testIntTime) on the server expires, it
SHALL set the local connection test action to TEST_ACT_STOP1 (phase 1
of graceful termination). This is simply a non-reversible state
awaiting the next message(s) to be sent from the server. During this
time, any received Load or Status PDUs are processed normally.
Upon transmission of the next Load or Status PDUs, the server SHALL
set the local connection test action to TEST_ACT_STOP2 (phase 2 of
graceful termination) and mark any outgoing PDUs with a testAction
value of TEST_ACT_STOP2. While in this state, the server MAY reduce
any Load PDU bursts to a size of one.
When the client receives a Load or Status PDU with the TEST_ACT_STOP2
indication, it SHALL finalize testing, display the test results, and
also mark its local connection with a test action of TEST_ACT_STOP2
(so that any PDUs subsequently received can be ignored).
With the test action of the client's connection set to
TEST_ACT_STOP2, the very next expiry of a send timer, for either a
Load or Status PDU, SHALL result in it and any subsequent PDUs to be
sent with a testAction value of TEST_ACT_STOP2 (as confirmation to
the server). While in this state, the client MAY reduce any Load PDU
bursts to a size of one. The client SHALL then schedule an immediate
end time for the connection.
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When the server receives the TEST_ACT_STOP2 confirmation in the Load
or Status PDU, the server SHALL schedule an immediate end time for
the connection which closes the socket and deallocates the associated
resources. The TEST_ACT_STOP2 exchange constitutes a graceful
termination of the test.
In a non-graceful test stop due to path failure, the watchdog
timeouts at each endpoint will expire (sometimes at one endpoint
first), notifications in logs, STDOUT, and/or formatted output SHALL
be made, and the endpoint SHALL schedule an immediate end time for
the connection.
If an attacker clears the TEST_ACT_STOP2 indication, then the
configured test duration timer (testIntTime) at the server and client
SHALL take precedence and the endpoint SHALL schedule an immediate
end time for the connection.
9. Operational considerations for the Measurement Method
The architecture of the method requires two cooperating hosts
operating in the roles of Src (test packet sender) and Dst
(receiver), with a measured path and return path between them.
The nominal duration of a measurement interval at the Destination,
parameter testIntTime, MUST be constrained in a production network,
since this is an active test method and it will likely cause
congestion on the Src to Dst host path during a test.
It is RECOMMENDED to locate test endpoints as close to the intended
measured link(s) as practical. The testing operator MUST set a value
for the MaxHops Parameter, based on the expected path length. This
Parameter can keep measurement traffic from straying too far beyond
the intended path.
It is obviously counterproductive to run more than one independent
and concurrent test (regardless of the number of flows in the test
stream) attempting to measure the maximum capacity on a single path.
The number of concurrent, independent tests of a path SHALL be
limited to one.
The load rate adjustment algorithm's scope is limited to helping
determine the Maximum IP-Layer Capacity in the context of an
infrequent, diagnostic, short-term measurement. It is RECOMMENDED to
discontinue non-measurement traffic that shares a subscriber's
dedicated resources while testing: measurements may not be accurate,
and throughput of competing elastic traffic may be greatly reduced.
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See section 8 of [RFC9097] for a discussion of the method of
measurement beyond purely operational aspects.
9.1. Notes on Interface Measurements
Additional measurements may be useful in specific circumstances. For
example, interface byte counters measured by a client at a
residential gateway are possible when the client application has
access to an interface that sees all traffic to/from a service
subscriber's location. Adding a byte counter at the client for
download or upload directions could be used to measure total traffic
and possibly detect when non-test traffic is present (and using
capacity). The client may not have the CPU cycles available to count
both the interface traffic and IP-layer Capacity simultaneously, so
this form of diagnostic measurement may not be possible.
10. Security Considerations
Active metrics and measurements have a long history of security
considerations. The security considerations that apply to any active
measurement of live paths are relevant here. See [RFC4656] and
[RFC5357].
When considering privacy of those involved in measurement or those
whose traffic is measured, the sensitive information available to
potential observers is greatly reduced when using active techniques
which are within this scope of work. Passive observations of user
traffic for measurement purposes raise many privacy issues. We refer
the reader to the privacy considerations described in the LMAP
Framework [RFC7594], which covers active and passive techniques.
There are some new considerations for Capacity measurement as
described in this document.
1. Cooperating client and server hosts and agreements to test the
path between the hosts are REQUIRED. Hosts perform in either the
server or client roles. One way to assure a cooperative
agreement employs the optional Authorization mode through the use
of the authDigest field and the known identity associated with
the shared key used to create the authDigest field via the KDF.
Other means are also possible, such as access control lists at
the server.
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2. It is REQUIRED to have a user client-initiated setup handshake
between cooperating hosts that allows firewalls to control
inbound unsolicited UDP traffic which either goes to a control
port or to ephemeral ports that are only created as needed.
Firewalls protecting each host can both continue to do their job
normally.
3. Client-server authentication and integrity protection for
feedback messages conveying measurements is RECOMMENDED. To
accommodate different host limitations and testing circumstances,
different modes of operation are available, as described in
Section 4 above.
4. Hosts MUST limit the number of simultaneous tests to avoid
resource exhaustion and inaccurate results.
5. Senders MUST be rate-limited. This can be accomplished using a
pre-built table defining all the offered sending rates that will
be supported. The default and optional load rate adjustment
algorithm results in "ramp up" from the lowest rate in the table.
Optionally, the server could utilize the maxBandwidth field (and
CHSR_USDIR_BIT bit) in the Setup Request from the client to limit
the maximum that it will attempt to achieve.
6. Service subscribers with limited data volumes who conduct
extensive capacity testing might experience the effects of
Service Provider controls on their service. Testing with the
Service Provider's measurement hosts SHOULD be limited in
frequency and/or overall volume of test traffic (for example, the
range of test interval duration values should be limited).
One specific attack that has been recognized is an on-path attack on
the testAction field where the attacker would set or clear the STOP
indication. Setting the indication in successive packets terminates
the test prematurely, with no threat to the Internet but annoyance
for the testers. If an attacker clears the STOP indication, the
mitigation relies on knowledge of the test duration at the client and
server, where these hosts cease all traffic when the specified test
duration is complete.
Authentication methods and requirements steadily evolve. Alternate
authentication modes provide for algorithm agility by defining a new
Mode, whose support is indicated by an assigning a suitable "Test
Setup PDU Authentication Mode Registry" value (see Section 11.3.4 ).
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11. IANA Considerations
This document requests IANA to assign a User/Registered UDP port for
the Test Setup exchange in the Control phase of protocol operation,
and to create a new registry group for the UDP Speed Test Protocol
(UDPSTP).
11.1. New User Port Number Assignment
IANA will allocate the following service name to the "Service Name
and Transport Protocol Port Number Registry" registry:
Service: udpstp
Transport Protocol: UDP
Assignee: IESG <iesg@ietf.org>
Contact: IETF Chair <chair@ietf.org>
Description: UDP-based IP-Layer Capacity and performance measurement
protocol
Reference: This RFC, RFCYYYY.
Port Number: <PORTNUM> of the IANA User Port range (1024-49151)
The protocol uses IP-Layer Unicast. The assignment of a single port
number is requested to help configure firewalls and other port-based
systems for access control prior to negotiating dynamic ports between
client and server.
11.2. New KeyTable KDF
IANA will allocate the following KDF to the existing list of
KeyTable KDFs (see https://www.iana.org/assignments/keytable/
keytable.xhtml#kdf).
KDF Description Reference
===============================================================
HMAC-SHA-256 HMAC using the SHA-256 hash [RFC6234]
11.3. New UDPSTP Registry Group
IANA will create the following registries in a new registry group
called "UDP Speed Test Protocol (UDPSTP)".
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IANA is requested to the following note under the "UDP Speed Test
Protocol (UDPSTP)" registry group:
Note: Values reserved for experimental use are not expected to be
used on the Internet, but for experiments that are confined to closed
environments.
11.3.1. PDU Identifier Registry
IANA will create the "PDU Identifier" registry under the "UDP Speed
Test Protocol (UDPSTP)" registry group. Every UDPSTP PDU contains a
two octet pduId field identifying the role and format of the PDU that
follows. The code points in this registry are allocated according to
the registration procedures [RFC8126] described in Table 1.
Range(Hex) Registration Procedures
===============================================================
0xFFFF and 0x0000 Reserved
0x8000-0xFFFE IETF Review
0x0001-0x7F00 Specification Required
0x7F01-0x7FE0 Experimental
0x7FE1-0x7FFF Private Use
Table 1: Registration procedures for the PDU Identifier registry
Initially, IANA will assign the "PDU Identifier" registry with the
values in Table 2:
Value Description Reference
===================================================
0xACE1 Test Setup PDU <this RFC>
0xACE2 Test Activation PDU <this RFC>
0xBEEF Load PDU <this RFC>
0xDEAD Null PDU <this RFC>
0xFEED Status Feedback PDU <this RFC>
Table 2: Initial PDU Identifier Values
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11.3.2. Protocol Version Registry
IANA will create the "Protocol Version" registry under the "UDP Speed
Test Protocol (UDPSTP)" registry group. UDPSTP Test Setup Request,
Test Setup Response and Test Activation Request PDUs contain a two
octet protocolVer field, identifying the version of the protocol in
use. The code points in this registry are allocated according to the
registration procedures [RFC8126] described in Table 3.
Range(Decimal) Registration Procedures
===============================================================
0-19 Reserved
20-40960 IETF Review
40961-53248 Specification Required
53249-65534 Experimental
65535 Reserved
Table 3: Registration procedures for the Protocol Version registry
Initially, IANA will assign the decimal value 20 listed in Table 4 in
the "Protocol Version" registry:
Value Reference
================================================
20 <this RFC>
Table 4: Initial Protocol Version value
11.3.3. Test Setup PDU Modifier Bitmap Registry
IANA will create the "Test Setup PDU Modifier Bitmap" registry under
the "UDP Speed Test Protocol (UDPSTP)" registry group. The Test
Setup PDU layout contains a modifierBitmap field. The bitmaps in
this registry are allocated according to the registration procedures
[RFC8126] described in Table 5.
Range(Bitmap) Registration Procedures
===============================================================
00000000-01111111 IETF Review
10000000 Reserved
Table 5: Registration procedures for the Test Setup PDU Modifier
Bitmap Registry
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Initially, IANA will assign the bitmap values defined by Table 6 in
the "Test Setup PDU Modifier Bitmap" registry.
Value Description Reference
===============================================================
0x00 No modifications <this RFC>
0x01 Allow Jumbo datagram <this RFC>
sizes above sending
rates of 1 Gbps
0x02 Use Traditional MTU <this RFC>
(1500 bytes with
IP-header)
Table 6: Initial Test Setup PDU Modifier Bitmap values
11.3.4. Test Setup PDU Authentication Mode Registry
IANA will create the "Test Setup PDU Authentication Mode" registry
under the "UDP Speed Test Protocol (UDPSTP)" registry group. The
Test Setup PDU layout contains an authMode field. The code points in
this registry are allocated according to the registration procedures
[RFC8126] described in Table 7.
Range(Decimal) Registration Procedures
===============================================================
0-59 IETF Review
60-63 Experimental
64-255 Reserved
Table 7: Registration procedures for the Test Setup PDU
Authentication Mode registry
Initially, IANA will assign the decimal values defined by Table 8 in
the "Test Setup PDU Authentication Mode" registry.
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Value Description Reference
===============================================================
0 Not used <this RFC>
1 Required authentication <this RFC>
for the Control phase
2 Optional authentication for <this RFC>
the Data phase, in addition
to the Control phase
Table 8: Initial Test Setup PDU Authentication Mode values
11.3.5. Test Setup PDU Command Response Field Registry
IANA will create the "Test Setup PDU Command Response Field" registry
under the "UDP Speed Test Protocol (UDPSTP)" registry group. The
Test Setup PDU layout contains a cmdResponse field. The code points
in this registry are allocated according to the registration
procedures [RFC8126] described in Table 9.
Range(Decimal) Registration Procedures
===============================================================
0-127 IETF Review
128-239 Specification Required
240-249 Experimental
250-254 Private Use
255 Reserved
Table 9: Registration procedures for the Test Setup PDU Command
Response Field Registry
Initially, IANA will assign the decimal values defined by Table 10 in
the "Test Setup PDU Command Response Field" registry.
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Value Description Reference
===============================================================
0 None (used by <this RFC>
client in Request)
1 Acknowledgment <this RFC>
2 Bad Protocol Version <this RFC>
3 Invalid Jumbo datagram <this RFC>
option
4 Unexpected Authentication <this RFC>
in Setup Request
5 Authentication missing <this RFC>
in Setup Request
6 Invalid authentication <this RFC>
method
7 Authentication failure <this RFC>
8 Authentication time is <this RFC>
invalid in Setup Request
9 No Maximum test Bit rate <this RFC>
specified
10 Server Maximum Bit rate <this RFC>
exceeded
11 MTU option does not match <this RFC>
server
12 Multi-connection parameters <this RFC>
rejected by server
13 Connection allocation <this RFC>
failure on server
Table 10: Initial Test Setup PDU Command Response Field values
Note that value 4 is required for backward compatibility with
previous experimental versions of software already in use. Further
note, value 6 signals that a client erroneously used an authMode
which hasn't been standardised yet (i.e., authMode greater than 1 or
2).
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11.3.6. Test Activation PDU Command Request Registry
IANA will create the "Test Activation PDU Command Request" registry
under the "UDP Speed Test Protocol (UDPSTP)" registry group. The
Test Setup PDU layout contains a cmdRequest field. The code points
in this registry are allocated according to the registration
procedures [RFC8126] described in Table 11.
Range(Decimal) Registration Procedures
===============================================================
0-127 IETF Review
128-239 Specification Required
240-249 Experimental
250-254 Private Use
255 Reserved
Table 11: Registration procedures for the Test Activation PDU Command
Request registry
Initially, IANA will assign the decimal values defined by Table 12 in
the "Test Activation PDU Command Request" registry.
Value Description Reference
===============================================================
0 No Request <this RFC>
1 Request test in Upstream <this RFC>
direction (client to server)
2 Request test in Downstream <this RFC>
direction (server to client)
Table 12: Initial Test Activation PDU Command Request values
11.3.7. Test Activation PDU Modifier Bitmap Registry
IANA will create the "Test Activation PDU Modifier Bitmap" registry
under the "UDP Speed Test Protocol (UDPSTP)" registry group. The
Test Activation PDU layout (also) contains a modifierBitmap field.
The bitmaps in this registry are allocated according to the
registration procedures [RFC8126] described in Table 13.
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Range(Bitmap) Registration Procedures
===============================================================
00000000-01111111 IETF Review
10000000 Reserved
Table 13: Registration procedures for the Test Activation PDU
Modifier Bitmap registry
Initially, IANA will assign the bitmap values defined by Table 14 in
the "Test Activation PDU Modifier Bitmap" registry.
Value Description Reference
===============================================================
0x00 No modifications <this RFC>
0x01 Set when srIndexConf is <this RFC>
start rate for search
0x02 Set for randomized <this RFC>
UDP payload
Table 14: Initial Test Activation PDU Modifier Bitmap values
11.3.8. Test Activation PDU Rate Adjustment Algo. Registry
The Test Activation PDU layout contains a rateAdjAlgo field. The
table below defines the assigned Capitalized alphabetic UTF-8 values
in the registry.
IANA will create the "Test Activation PDU Rate Adjustment Algo."
registry under the "UDP Speed Test Protocol (UDPSTP)" registry group.
The Test Activation PDU layout contains a rateAdjAlgo field. The
code points in this registry are allocated according to the
registration procedures [RFC8126] described in Table 15.
Range(Capital alphabet. UTF-8) Registration Procedures
==========================================================
A-Y IETF review
Z Reserved
Table 15: Registration procedures for the Test Activation PDU Rate
Adjustment Algo. registry
Initially, IANA will assign the Capitalized alphabetic UTF-8 values,
as well as the corresponding incremental numeric, defined by Table 16
in the "Test Activation PDU Rate Adjustment Algo." registry.
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Value(Numeric) Description Reference
========================================================
A(n/a) Not used <this RFC>
B(0) Rate algorithm Type B [Y.1540Amd2]
C(1) Rate algorithm Type C [TR-471]
Table 16: Initial Test Activation PDU Rate Adjustment Algo. values
11.3.9. Test Activation PDU Command Response Field Registry
IANA will create the "Test Activation PDU Command Response Field"
registry under the "UDP Speed Test Protocol (UDPSTP)" registry group.
The Test Activation PDU layout (also) contains a cmdResponse field.
The code points in this registry are allocated according to the
registration procedures [RFC8126] described in Table 17.
Range(Decimal) Registration Procedures
===============================================================
0-127 IETF Review
128-239 Specification Required
240-249 Experimental
250-254 Private Use
255 Reserved
Table 17: Registration procedures for the Test Activation PDU Command
Response Field registry
Initially, IANA will assign the decimal values defined by Table 18 in
the "Test Activation PDU Command Response Field" registry.
Value Description Reference
===============================================================
0 None (used by <this RFC>
client in Request)
1 Server Acknowledgment <this RFC>
2 Server indicates an error <this RFC>
Table 18: Initial Test Activation PDU Command Response Field values
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11.4. Guidelines for the Designated Experts
It is suggested that multiple designated experts be appointed for
registry change requests.
Criteria that should be applied by the designated experts include
determining whether the proposed registration duplicates existing
entries and whether the registration description is clear and fits
the purpose of this registry.
Registration requests are evaluated within a two-week review period
on the advice of one or more designated experts. Within the review
period, the designated experts will either approve or deny the
registration request, communicating this decision to IANA. Denials
should include an explanation and, if applicable, suggestions as to
how to make the request successful.
12. Acknowledgments
This document was edited by Al Morton, who passed away before being
able to finalize this work. Ruediger Geib only joined later to help
finalize this draft.
Thanks to Lincoln Lavoie, Can Desem, Greg Mirsky, Bjoern Ivar Teigen,
Ken Kerpez and Chen Li for reviewing this draft and providing helpful
suggestions and areas for further development. Mohamed Boucadair's
AD review improved comprehensibility of the document and he further
navigated the document well through the final review stages. Tommy
Pauly shepherded this document. Further comments by Gorry Fairhurst,
Eric Vyncke, Roman Danyliw, Gunter van de Velde, Deb Cooley, Tianran
Zhou, Andy Newton, Giuseppe Fioccola, Lars Eggert, Erik Kline and
Benson Muite helped to shape the document. David Dong and Amanda
Baber provided early reviews of the IANA Considerations section.
Starting with the early SEC-DIR review, Brian Weis provided very
constructive guidance regarding numerous security related protocol
issues. Crypto Forum RG reviewed these parts, again providing
guidance. Magnus Westerlund's review resulted in further changes and
refinements. Ultimately, Paul Wouters' feedback was critical in
finalizing the chosen security approach.
13. References
13.1. Normative References
[C-Prog] ISO/IEC, "ISO/IEC 9899:1999 Programming languages - C",
1999.
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[NIST800-108]
Chen, LC., "Recommendation for Key Derivation Using
Pseudorandom Functions (Revised, Update 1)", August 2022,
<https://nvlpubs.nist.gov/nistpubs/SpecialPublications/
NIST.SP.800-108r1-upd1.pdf>.
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
DOI 10.17487/RFC0768, August 1980,
<https://www.rfc-editor.org/info/rfc768>.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5044] Culley, P., Elzur, U., Recio, R., Bailey, S., and J.
Carrier, "Marker PDU Aligned Framing for TCP
Specification", RFC 5044, DOI 10.17487/RFC5044, October
2007, <https://www.rfc-editor.org/info/rfc5044>.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234,
DOI 10.17487/RFC6234, May 2011,
<https://www.rfc-editor.org/info/rfc6234>.
[RFC7210] Housley, R., Polk, T., Hartman, S., and D. Zhang,
"Database of Long-Lived Symmetric Cryptographic Keys",
RFC 7210, DOI 10.17487/RFC7210, April 2014,
<https://www.rfc-editor.org/info/rfc7210>.
[RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
March 2017, <https://www.rfc-editor.org/info/rfc8085>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
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[RFC8899] Fairhurst, G., Jones, T., Tüxen, M., Rüngeler, I., and T.
Völker, "Packetization Layer Path MTU Discovery for
Datagram Transports", RFC 8899, DOI 10.17487/RFC8899,
September 2020, <https://www.rfc-editor.org/info/rfc8899>.
[RFC9097] Morton, A., Geib, R., and L. Ciavattone, "Metrics and
Methods for One-Way IP Capacity", RFC 9097,
DOI 10.17487/RFC9097, November 2021,
<https://www.rfc-editor.org/info/rfc9097>.
[TR-471] Morton, A,, Editor., "Broadband Forum TR-471: IP Layer
Capacity Metrics and Measurement, Issue 4", September
2024, <https://www.broadband-forum.org/technical/download/
TR-471.pdf>.
[Y.1540] ITU-T, "Internet protocol data communication service - IP
packet transfer and availability performance parameters",
ITU-T Recommendation Y.1540, December 2019,
<https://www.itu.int/rec/T-REC-Y.1540-201912-I/en>.
[Y.1540Amd2]
ITU-T, "Internet protocol data communication service - IP
packet transfer and availability performance parameters
Amendment 2 - Revised Annex B: Additional search
algorithms for IP-based capacity parameters and methods of
measurement", ITU-T Recommendation Y.1540 Amd. 2, March
2023, <https://www.itu.int/rec/T-REC-Y.1540-201912-I/en>.
13.2. Informative References
[EVP_KDF-KB]
"The Key-Based EVP_KDF implementation",
<https://docs.openssl.org/master/man7/EVP_KDF-KB/>.
[RFC3148] Mathis, M. and M. Allman, "A Framework for Defining
Empirical Bulk Transfer Capacity Metrics", RFC 3148,
DOI 10.17487/RFC3148, July 2001,
<https://www.rfc-editor.org/info/rfc3148>.
[RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M.
Zekauskas, "A One-way Active Measurement Protocol
(OWAMP)", RFC 4656, DOI 10.17487/RFC4656, September 2006,
<https://www.rfc-editor.org/info/rfc4656>.
[RFC5136] Chimento, P. and J. Ishac, "Defining Network Capacity",
RFC 5136, DOI 10.17487/RFC5136, February 2008,
<https://www.rfc-editor.org/info/rfc5136>.
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[RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J.
Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)",
RFC 5357, DOI 10.17487/RFC5357, October 2008,
<https://www.rfc-editor.org/info/rfc5357>.
[RFC7497] Morton, A., "Rate Measurement Test Protocol Problem
Statement and Requirements", RFC 7497,
DOI 10.17487/RFC7497, April 2015,
<https://www.rfc-editor.org/info/rfc7497>.
[RFC7594] Eardley, P., Morton, A., Bagnulo, M., Burbridge, T.,
Aitken, P., and A. Akhter, "A Framework for Large-Scale
Measurement of Broadband Performance (LMAP)", RFC 7594,
DOI 10.17487/RFC7594, September 2015,
<https://www.rfc-editor.org/info/rfc7594>.
[RFC8337] Mathis, M. and A. Morton, "Model-Based Metrics for Bulk
Transport Capacity", RFC 8337, DOI 10.17487/RFC8337, March
2018, <https://www.rfc-editor.org/info/rfc8337>.
[RFC8762] Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple
Two-Way Active Measurement Protocol", RFC 8762,
DOI 10.17487/RFC8762, March 2020,
<https://www.rfc-editor.org/info/rfc8762>.
[RFC9145] Boucadair, M., Reddy.K, T., and D. Wing, "Integrity
Protection for the Network Service Header (NSH) and
Encryption of Sensitive Context Headers", RFC 9145,
DOI 10.17487/RFC9145, December 2021,
<https://www.rfc-editor.org/info/rfc9145>.
Appendix A. KDF Example (OpenSSL)
<CODE BEGINS>
//
// Output individual authentication keys of length SHA256_KEY_LEN
// from derived key material.
//
// Return Values: 0 = Failure, 1 = Success
//
int kdf_hmac_sha256(char *Kin, uint32_t authUnixTime,
unsigned char *cAuthKey, // Client key
unsigned char *sAuthKey) { // Server key
int var, keylen = SHA256_KEY_LEN * 2;
char context[16];
unsigned char *keyptr, keybuf[keylen];
EVP_KDF *kdf = NULL;
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EVP_KDF_CTX *kctx = NULL;
OSSL_PARAM params[16], *p = params;
//
// Fetch KDF algorithm and create context
//
if ((kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL)) == NULL) {
return 0;
}
if ((kctx = EVP_KDF_CTX_new(kdf)) == NULL) {
EVP_KDF_free(kdf);
return 0;
}
//
// Set parameters for KBKDF
// ---------------------------------------------------------
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MODE, "COUNTER", 0);
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC, "HMAC", 0);
*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST, "SHA256", 0);
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY, Kin, strlen(Kin));
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT, "UDPSTP", 6);
var = snprintf(context, sizeof(context), "%u", authUnixTime);
*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO, context, var);
//
// Confirm the following are enabled
//
var = 1;
*p++ = OSSL_PARAM_construct_int(OSSL_KDF_PARAM_KBKDF_USE_L, &var);
*p++ = OSSL_PARAM_construct_int(OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR, &var);
//
// Set counter length in bits (available as of OpenSSL 3.1)
//
var = 32; // Length of 32 is backward compatible with OpenSSL 3.0
*p++ = OSSL_PARAM_construct_int(OSSL_KDF_PARAM_KBKDF_R, &var);
*p++ = OSSL_PARAM_construct_end();
// ---------------------------------------------------------
//
// Derive key material
//
if (EVP_KDF_derive(kctx, keybuf, keylen, params) < 1) {
EVP_KDF_CTX_free(kctx);
EVP_KDF_free(kdf);
return 0;
}
//
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// Output individual keys
//
keyptr = keybuf;
memcpy(cAuthKey, keyptr, SHA256_KEY_LEN);
keyptr += SHA256_KEY_LEN;
memcpy(sAuthKey, keyptr, SHA256_KEY_LEN);
//
// Cleanup
//
EVP_KDF_CTX_free(kctx);
EVP_KDF_free(kdf);
return 1;
}
<CODE ENDS>
Figure 12: KDF Example Code Snippet
Authors' Addresses
Len Ciavattone
AT&T Labs
Middletown, NJ
United States of America
Email: lenciavattone@gmail.com
Ruediger Geib
Deutsche Telekom
Deutsche Telekom Allee 9
64295 Darmstadt
Germany
Phone: +49 6151 5812747
Email: Ruediger.Geib@telekom.de
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