Internet Engineering Task Force (IETF) Z. Li

Internet Engineering Task Force (IETF) Z. Li
Request for Comments: 9534 China Mobile
Category: Standards Track T. Zhou
ISSN: 2070-1721 Huawei
J. Guo
ZTE Corp.
G. Mirsky
Ericsson
R. Gandhi
Cisco Systems, Inc.
January 2024

Simple Two-Way Active Measurement Protocol Extensions for Performance
Measurement on a Link Aggregation Group

Abstract

This document extends Simple Two-way Active Measurement Protocol
(STAMP) to implement performance measurement on every member link of
a Link Aggregation Group (LAG). Knowing the measured metrics of each
member link of a LAG enables operators to enforce a performance-based
traffic steering policy across the member links.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc9534.

Copyright Notice

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Table of Contents

1. Introduction
1.1. Requirements Language
2. Micro Sessions on a LAG
3. Member Link Validation
3.1. Micro-session ID TLV
3.2. Micro STAMP-Test Procedures
4. Applicability
5. IANA Considerations
6. Security Considerations
7. References
7.1. Normative References
7.2. Informative References
Acknowledgements
Authors' Addresses

1. Introduction

A Link Aggregation Group (LAG), as defined in [IEEE802.1AX], provides
mechanisms to combine multiple physical links into a single logical
link. This logical link offers higher bandwidth and better
resiliency because, if one of the physical member links fails, the
aggregate logical link can continue to forward traffic over the
remaining operational physical member links.

Usually, when forwarding traffic over a LAG, a hash-based mechanism
is used to load balance the traffic across the LAG member links. The
link delay might vary between member links because of different
transport paths, especially when a LAG is used in a wide area
network. To provide low-latency service for time-sensitive traffic,
we need to explicitly steer the traffic across the LAG member links
based on the link delay, loss, and so on. That requires a solution
to measure the performance metrics of each member link of a LAG.
Hence, the measured performance metrics can work together with Layer
2 bundle member link attributes advertisement [RFC8668] for traffic
steering.

According to the classifications in [RFC7799], Simple Two-way Active
Measurement Protocol (STAMP) [RFC8762] is an active measurement
method, and it can complement passive and hybrid methods. It
provides a mechanism to measure both one-way and round-trip
performance metrics, like delay, delay variation, and packet loss. A
STAMP test session over the LAG can be used to measure the
performance of a member link using a specially constructed 5-tuple.
The session can be used to measure an average of some or all member
links of the LAG by varying one or more elements of that 5-tuple.
However, without the knowledge of each member link, a STAMP test
session cannot measure the performance of every physical member link.

This document extends STAMP to implement performance measurement on
every member link of a LAG. It can provide the same metrics as
One-Way Active Measurement Protocol (OWAMP) [RFC4656] and Two-Way
Active Measurement Protocol (TWAMP) [RFC5357] can measure, such as
delay, jitter, and packet loss.

1.1. 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. Micro Sessions on a LAG

This document addresses the scenario where a LAG directly connects
two nodes. An example of this is in Figure 1, where the LAG
consisting of four links connects nodes A and B. The goal is to
measure the performance of each link of the LAG.

+---+ +---+
| |-----------------------| |
| A |-----------------------| B |
| |-----------------------| |
| |-----------------------| |
+---+ +---+

Figure 1: Performance Measurement on a LAG

To measure the performance metrics of every member link of a LAG,
multiple sessions (one session for each member link) need to be
established between the two endpoints that are connected by the LAG.
These sessions are called "micro sessions" in the remainder of this
document. Although micro sessions are in fact STAMP sessions
established on member links of a LAG, test packets of micro sessions
MUST carry member link information for validation.

All micro sessions of a LAG share the same Sender IP Address and
Receiver IP Address. As for the UDP port, the micro sessions may
share the same Sender Port and Receiver Port pair or each micro
session may be configured with a different Sender Port and Receiver
Port pair. From the operational point of view, the former is simpler
and is RECOMMENDED.

Test packets of a micro session MUST carry the member link
information for validation checks. For example, when a micro STAMP
Session-Sender receives a reflected test packet, it checks whether
the test packet is from the expected member link. The member link
information is encoded in the Micro-session ID TLV introduced in
Section 3, which also provides a detailed description about member
link validation.

A micro STAMP Session-Sender MAY include the Follow-Up Telemetry TLV
[RFC8972] to request information from the micro Session-Reflector.
This timestamp might be important for the micro Session-Sender, as it
improves the accuracy of network delay measurement by minimizing the
impact of egress queuing delays on the measurement.

3. Member Link Validation

Test packets MUST carry member link information in the Micro-session
ID TLV introduced in this section for validation checks. The micro
Session-Sender verifies whether the test packet is received from the
expected member link. It also verifies whether the packet is sent
from the expected member link at the Reflector side. The micro
Session-Reflector verifies whether the test packet is received from
the expected member link.

3.1. Micro-session ID TLV

The STAMP TLV mechanism [RFC8972] extends STAMP test packets with one
or more optional TLVs. This document defines the TLV Type (value 11)
for the Micro-session ID TLV that carries the micro STAMP Session-
Sender member link identifier and Session-Reflector member link
identifier in the Sender Micro-session ID field and the Reflector
Micro-session ID field, respectively. The format of the Micro-
session ID TLV is shown as follows:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|STAMP TLV Flags| Type = 11 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender Micro-session ID | Reflector Micro-session ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Figure 2: Micro-session ID TLV

Type (1 octet in length): This field is defined to indicate this TLV
is a Micro-session ID TLV. Value 11 has been allocated by IANA
(Section 5).

Length (2 octets in length): This field is defined to carry the
length of the Value field in octets. The Length field value MUST
be 4.

Sender Micro-session ID (2 octets in length): This field is defined
to carry the LAG member link identifier of the Sender side. In
the future, it may be used generically to cover use cases beyond
LAGs. The value of this field MUST be unique within a STAMP
session at the Session-Sender.

Reflector Micro-session ID (2 octets in length): This field is
defined to carry the LAG member link identifier of the Reflector
side. In the future, it may be used generically to cover use
cases beyond LAGs. The value of this field MUST be unique within
a STAMP session at the Session-Reflector.

3.2. Micro STAMP-Test Procedures

The micro STAMP-Test reuses the procedures as defined in Section 4 of
STAMP [RFC8762] with the following additions.

The micro STAMP Session-Sender MUST send the micro STAMP-Test packets
over the member link with which the session is associated. The
mapping between a micro STAMP session and the Sender/Reflector member
link identifiers can be configured by augmenting the STAMP YANG
[STAMP-YANG]. The detailed augmentation is not in the scope of this
document.

When sending a test packet, the micro STAMP Session-Sender MUST set
the Sender Micro-session ID field with the member link identifier
associated with the micro STAMP session. If the Session-Sender knows
the Reflector member link identifier, the Reflector Micro-session ID
field MUST be set. Otherwise, the Reflector Micro-session ID field
MUST be zero. The Reflector member link identifier can be obtained
from preconfiguration or learned from data plane (e.g., the reflected
test packet). This document does not specify the way to obtain the
Reflector member link identifier.

When the micro STAMP Session-Reflector receives a test packet, if the
Reflector Micro-session ID is not zero, the micro STAMP Session-
Reflector MUST use the Reflector member link identifier to check
whether it is associated with the micro STAMP session. If the
validation fails, the test packet MUST be discarded. If the
Reflector Micro-session ID is zero, it will not be verified. If all
validations passed, the Session-Reflector sends a reflected test
packet to the Session-Sender. The micro STAMP Session-Reflector MUST
put the Sender and Reflector member link identifiers that are
associated with the micro STAMP session in the Sender Micro-session
ID and Reflector Micro-session ID fields, respectively. The Sender
member link identifier is copied from the received test packet.

When receiving a reflected test packet, the micro Session-Sender MUST
use the Sender Micro-session ID to validate whether the reflected
test packet is correctly received from the expected member link. If
the validation fails, the test packet MUST be discarded. The micro
Session-Sender MUST use the Reflector Micro-session ID to validate
the Reflector's behavior. If the validation fails, the test packet
MUST be discarded.

Two modes of the STAMP Session-Reflector, stateless and stateful,
characterize the expected behavior as described in Section 4 of STAMP
[RFC8762]. The micro STAMP-Test also supports both stateless and
stateful modes. However, the micro STAMP-Test does not introduce any
additional state to STAMP, i.e., any procedure with regard to the
Micro-session ID is stateless.

4. Applicability

The micro STAMP Session-Sender sends micro Session-Sender packets
with the Micro-session ID TLV. The micro Session-Reflector checks
whether a test packet is received from the member link associated
with the correct micro STAMP session if the Reflector Micro-session
ID field is set. When reflecting, the micro STAMP Session-Reflector
copies the Sender Micro-session ID from the received micro Session-
Sender packet to the micro Session-Reflector packet and sets the
Reflector Micro-session ID field with the member link identifier that
is associated with the micro STAMP session. When receiving the micro
Session-Reflector packet, the micro Session-Sender uses the Sender
Micro-session ID to check whether the packet is received from the
member link associated with the correct micro STAMP session. The
micro Session-Sender also use the Reflector Micro-session ID to
validate the Reflector's behavior.

5. IANA Considerations

IANA has allocated the following STAMP TLV Type for the Micro-session
ID TLV in the "STAMP TLV Types" registry [RFC8972]:

+=======+==================+===============+
| Value | Description | Reference |
+=======+==================+===============+
| 11 | Micro-session ID | This Document |
+-------+------------------+---------------+

Table 1: New STAMP TLV Type

6. Security Considerations

The STAMP extension defined in this document is intended for
deployment in the LAG scenario where Session-Sender and Session-
Reflector are directly connected. As such, it's assumed that a node
involved in a STAMP operation has previously verified the integrity
of the LAG connection and the identity of its one-hop-away peer node.

This document does not introduce any additional security issues, and
the security mechanisms defined in [RFC8762] and [RFC8972] apply in
this document.

7. References

7.1. Normative References

[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>.

[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>.

[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>.

[RFC8972] Mirsky, G., Min, X., Nydell, H., Foote, R., Masputra, A.,
and E. Ruffini, "Simple Two-Way Active Measurement
Protocol Optional Extensions", RFC 8972,
DOI 10.17487/RFC8972, January 2021,
<https://www.rfc-editor.org/info/rfc8972>.

7.2. Informative References

[IEEE802.1AX]
IEEE, "IEEE Standard for Local and Metropolitan Area
Networks -- Link Aggregation", IEEE Std 802.1AX-2020,
DOI 10.1109/IEEESTD.2020.9105034, May 2020,
<https://ieeexplore.ieee.org/document/9105034>.

[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>.

[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>.

[RFC7799] Morton, A., "Active and Passive Metrics and Methods (with
Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
May 2016, <https://www.rfc-editor.org/info/rfc7799>.

[RFC8668] Ginsberg, L., Ed., Bashandy, A., Filsfils, C., Nanduri,
M., and E. Aries, "Advertising Layer 2 Bundle Member Link
Attributes in IS-IS", RFC 8668, DOI 10.17487/RFC8668,
December 2019, <https://www.rfc-editor.org/info/rfc8668>.

[STAMP-YANG]
Mirsky, G., Min, X., Luo, W. S., and R. Gandhi, "Simple
Two-way Active Measurement Protocol (STAMP) Data Model",
Work in Progress, Internet-Draft, draft-ietf-ippm-stamp-
yang-12, 5 November 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-ippm-
stamp-yang-12>.

Acknowledgements

The authors would like to thank Mach Chen, Min Xiao, Fang Xin, Marcus
Ihlar, and Richard Foote for the valuable comments to this work.

Authors' Addresses

Zhenqiang Li
China Mobile
No. 29 Finance Avenue
Xicheng District
Beijing
China
Email: [email protected]

Tianran Zhou
Huawei
China
Email: [email protected]

Jun Guo
ZTE Corp.
China
Email: [email protected]

Greg Mirsky
Ericsson
United States of America
Email: [email protected]

Rakesh Gandhi
Cisco Systems, Inc.
Canada
Email: [email protected]