Advertising IGP Measurement Group using TLV
draft-admnr-lsr-igp-measurement-group-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Mahesh Jethanandani , Derek M. Yeung , Acee Lindem , Reshad Rahman , Nico Strina | ||
| Last updated | 2026-02-03 | ||
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draft-admnr-lsr-igp-measurement-group-00
Internet Engineering Task Force M. Jethanandani, Ed.
Internet-Draft D. Yeung, Ed.
Intended status: Standards Track A. Lindem, Ed.
Expires: 7 August 2026 Arrcus, Inc
R. Rahman, Ed.
N. Strina
Equinix, Inc
3 February 2026
Advertising IGP Measurement Group using TLV
draft-admnr-lsr-igp-measurement-group-00
Abstract
This document defines an IS-IS capability sub-TLV for advertising
measurement group membership for Active Measurement Protocols (AMPs)
such as TWAMP and STAMP. The mechanism allows IGP routers to
discover other routers participating in different measurement groups,
enabling automatic discovery of measurement endpoints across IGP
areas. The solution uses interface addresses (IPv4 or IPv6) to
identify measurement group membership, where the same interface
address may be used for multiple measurement groups.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 7 August 2026.
Copyright Notice
Copyright (c) 2026 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 . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Use Case . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IS-IS Active Measurement Protocol Measurement Group
Sub-TLV . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Protocol Flags . . . . . . . . . . . . . . . . . . . . . 5
4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5.1. IS-IS Router Capability TLV Sub-TLVs . . . . . . . . . . 6
5.2. AMP Measurement Group Protocol Flags Registry . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
In network deployments, different IGP routers may participate in
different measurement groups for various purposes. For example, one
measurement group may be used for TWAMP (Two-Way Active Measurement
Protocol), another for STAMP (Simple Two-Way Active Measurement
Protocol), and yet another for other measurement or operational
purposes.
To enable automatic discovery and configuration of these measurement
groups, there is a need for IGP routers to discover which other
routers are participating in which measurement groups. This
discovery mechanism must work whether the participating routers are
in the same IGP area or not, which implies that the information must
be leakable across area boundaries.
This document defines an IS-IS capability sub-TLV, similar to the
seamless BFD discriminators mechanism defined in [RFC7883], that
allows routers to advertise their measurement group membership. The
mechanism uses interface addresses (IPv4 or IPv6) to identify
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measurement group membership, where the interface address may be
associated with either a physical interface or a loopback interface.
The same interface address may be used to indicate membership in
multiple measurement groups.
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. Use Case
At a high level, different IGP routers participate in different
measurement groups. For example, measurement group A may be used for
TWAMP, measurement group B for STAMP, and measurement group C for
another purpose.
The requirements for measurement group discovery are:
* IGP routers MUST be able to discover which routers are
participating in which measurement groups.
* Discovery MUST work whether participating routers are in the same
IGP area or not, which implies that the information MUST be
leakable across area boundaries.
* An interface address (IPv4 or IPv6) is used to identify the
membership of a particular measurement group.
* The interface address MAY be associated with either a physical
interface or a loopback interface.
* The same interface address MAY be used for multiple measurement
groups.
Since loopback support is required, and there is no adjacency created
over loopback interfaces to carry Adjacency Segment Identifier (ASLA)
information, the solution uses an IS-IS capability sub-TLV similar to
seamless BFD discriminators [RFC7883]. This approach allows the
advertisement of measurement group membership information in the
Router Capability TLV, which is propagated across area boundaries.
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3. IS-IS Active Measurement Protocol Measurement Group Sub-TLV
This document defines a new IS-IS capability sub-TLV for advertising
Active Measurement Protocol (AMP) measurement group membership. The
sub-TLV is carried in the IS-IS Router Capability TLV (TLV 242) as
defined in [RFC7981].
The Active Measurement Protocol Measurement Group sub-TLV has the
following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Protocol Flags| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv4 or IPv6 Host Address (4 or 16 octets) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: AMP Measurement Group Sub-TLV Format
Fields:
Type:
TBD (to be assigned by IANA)
Length:
1 octet. The length of the value field in octets. For IPv4
addresses, the length MUST be 6. For IPv6 addresses, the length
MUST be 18.
Protocol Flags:
1 octet. A bit field indicating which Active Measurement
Protocols are supported on this endpoint. Bit definitions are
specified in Section 3.1.
Reserved:
1 octet. MUST be set to zero on transmission and MUST be ignored
on receipt.
IPv4 or IPv6 Host Address:
4 octets for IPv4 or 16 octets for IPv6. The interface address
(IPv4 or IPv6) that identifies this endpoint's membership in the
measurement groups indicated by the Protocol Flags field. This
address MAY be associated with a physical interface or a loopback
interface.
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Multiple instances of this sub-TLV MAY be included in the Router
Capability TLV to advertise multiple endpoints, each potentially
supporting different combinations of Active Measurement Protocols.
3.1. Protocol Flags
The Protocol Flags field is an 8-bit field where each bit indicates
support for a specific Active Measurement Protocol. The bit
assignments are as follows:
+=====+==========+===============================+
| Bit | Protocol | Reference |
+=====+==========+===============================+
| 0 | TWAMP | [RFC5357] |
+-----+----------+-------------------------------+
| 1 | STAMP | [RFC8762] |
+-----+----------+-------------------------------+
| 2-7 | Reserved | For future assignment by IANA |
+-----+----------+-------------------------------+
Table 1
Bits are numbered from 0 (most significant bit) to 7 (least
significant bit). A bit value of 1 indicates that the endpoint
supports the corresponding protocol for the measurement group
identified by the Host Address. A bit value of 0 indicates that the
endpoint does not support that protocol.
Multiple bits MAY be set to indicate that the endpoint supports
multiple protocols, meaning the same interface address is used for
multiple measurement groups.
4. Operations
A router that participates in one or more Active Measurement Protocol
measurement groups MUST advertise the AMP Measurement Group sub-TLV
in its Router Capability TLV. For each endpoint (interface address)
that participates in measurement groups, the router MUST include one
instance of the sub-TLV with the appropriate Protocol Flags bits set.
If an endpoint supports multiple protocols (e.g., both TWAMP and
STAMP), the router MAY either:
* Include a single sub-TLV instance with multiple Protocol Flags
bits set, or
* Include multiple sub-TLV instances, each with a single Protocol
Flags bit set.
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Routers receiving the AMP Measurement Group sub-TLV MUST process the
information to build their measurement group membership database.
This information is used to discover other routers participating in
the same measurement groups, enabling automatic configuration of
measurement sessions.
The Router Capability TLV, and thus the AMP Measurement Group sub-
TLV, is propagated across IS-IS area boundaries when area leaking is
configured, satisfying the requirement for cross-area discovery.
If a router's measurement group membership changes, it MUST update
its Router Capability TLV advertisement accordingly. Routers
receiving updated information MUST process the changes and update
their measurement group membership database.
5. IANA Considerations
5.1. IS-IS Router Capability TLV Sub-TLVs
IANA is requested to assign a new sub-TLV type from the "IS-IS Router
Capability TLV sub-TLVs" registry for the Active Measurement Protocol
Measurement Group sub-TLV defined in this document.
5.2. AMP Measurement Group Protocol Flags Registry
IANA is requested to create a new registry called "AMP Measurement
Group Protocol Flags" under the "Interior Gateway Protocol (IGP)
Parameters" registry group. The registry should track bit
assignments for Active Measurement Protocols in the Protocol Flags
field of the AMP Measurement Group sub-TLV.
The initial assignments are:
+=====+============+==========================+
| Bit | Protocol | Reference |
+=====+============+==========================+
| 0 | TWAMP | [RFC5357], this document |
+-----+------------+--------------------------+
| 1 | STAMP | [RFC8762], this document |
+-----+------------+--------------------------+
| 2-7 | Unassigned | |
+-----+------------+--------------------------+
Table 2
Future assignments are to be made through IETF Review [RFC8126].
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6. Security Considerations
This document defines a mechanism for advertising measurement group
membership in IS-IS. The security considerations for IS-IS as
specified in [RFC1195] and [RFC5304] apply.
An attacker that can inject false AMP Measurement Group sub-TLVs
could cause routers to attempt to establish measurement sessions with
incorrect endpoints, potentially leading to:
* Failed measurement sessions
* Misconfiguration of measurement infrastructure
* Resource exhaustion if many false endpoints are advertised
To mitigate these risks, implementations SHOULD authenticate IS-IS
protocol exchanges using the mechanisms defined in [RFC5304] for IS-
IS authentication. Additionally, operators SHOULD configure
appropriate access controls and monitoring to detect and prevent
unauthorized advertisements.
The information advertised in the AMP Measurement Group sub-TLV
reveals which routers are participating in measurement groups and
which interface addresses are used for measurement purposes. This
information may be considered sensitive in some deployments.
Operators should consider the implications of this information
disclosure when deploying this mechanism.
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>.
[RFC7883] Ginsberg, L., Akiya, N., and M. Chen, "Advertising
Seamless Bidirectional Forwarding Detection (S-BFD)
Discriminators in IS-IS", RFC 7883, DOI 10.17487/RFC7883,
July 2016, <https://www.rfc-editor.org/info/rfc7883>.
[RFC7981] Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions
for Advertising Router Information", RFC 7981,
DOI 10.17487/RFC7981, October 2016,
<https://www.rfc-editor.org/info/rfc7981>.
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[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>.
7.2. Informative References
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, DOI 10.17487/RFC1195,
December 1990, <https://www.rfc-editor.org/info/rfc1195>.
[RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic
Authentication", RFC 5304, DOI 10.17487/RFC5304, October
2008, <https://www.rfc-editor.org/info/rfc5304>.
[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>.
[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>.
Acknowledgements
The authors would like to thank the participants in the IETF
discussions that led to this document.
Authors' Addresses
Mahesh Jethanandani (editor)
Arrcus, Inc
Street
City, Region Postal code
United States of America
Phone: Phone
Email: mjethanandani@gmail.com
URI: URI
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Derek Yeung (editor)
Arrcus, Inc
Street
City, Region Postal code
United States of America
Phone: Phone
Email: derek@arrcus.com
URI: URI
Acee Lindem (editor)
Arrcus, Inc
Street
City, Region Postal code
United States of America
Phone: Phone
Email: acee.ietf@gmail.com
URI: URI
Reshad Rahman (editor)
Equinix, Inc
Street
City Region Postal code
Canada
Phone: Phone
Email: reshad@yahoo.com
URI: URI
Nico Strina
Equinix, Inc
Street
City, Region Postal code
United States of America
Phone: Phone
Email: nstrina@equinix.com
URI: URI
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