Internet-Draft Signaling FLC and FRLD August 2023
Min, et al. Expires 7 February 2024 [Page]
Workgroup:
LSR Working Group
Internet-Draft:
draft-xzc-lsr-mpls-flc-frld-03
Published:
Intended Status:
Standards Track
Expires:
Authors:
X. Min
ZTE Corp.
Z. Zhang
ZTE Corp.
W. Cheng
China Mobile

Signaling Flow-ID Label Capability and Flow-ID Readable Label Depth

Abstract

Flow-ID Label (FL) is used for MPLS flow identification and flow-based performance measurement with alternate marking method. The ability to process Flow-ID labels is called Flow-ID Label Capability (FLC), and the capability of reading the maximum label stack depth and performing FL-based performance measurement is called Flow-ID Readable Label Depth (FRLD). This document defines a mechanism to signal the FLC and the FRLD using IGP and BGP-LS.

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 7 February 2024.

Table of Contents

1. Introduction

As specified in [I-D.ietf-mpls-inband-pm-encapsulation], Flow-ID Label (FL) is used for MPLS flow identification and flow-based performance measurement with alternate marking method.

Flow-ID Label may appear multiple times in a label stack with variable depth, so both the Flow-ID Label Capability (FLC) and the Flow-ID Readable Label Depth (FRLD) are defined in [I-D.ietf-mpls-inband-pm-encapsulation].

Analogous to [RFC9088] and [RFC9089], this document defines a mechanism to signal the FLC and the FRLD using IGP and BGP-LS. Specifically, IGP includes IS-IS, OSPFv2 and OSPFv3.

1.1. Terminology

This memo makes use of the terms defined in [I-D.ietf-mpls-inband-pm-encapsulation] and [RFC8491].

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. Advertising FLC Using IGP

FLC is a property of the node, so FLC is advertised with a node in this document.

If a router has multiple interfaces, the router MUST NOT announce FLC unless all of its interfaces are capable of processing FL.

2.1. Advertising FLC Using IS-IS

[RFC8667] defines an SR-Capabilities sub-TLV of the IS-IS Router Capability TLV as defined in [RFC7981]. Bit 2 in the Flags field of the SR-Capabilities sub-TLV is used as the FLC Flag (F-Flag), as shown in Figure 1.

 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|I|V|F|         |
+-+-+-+-+-+-+-+-+
Figure 1: Flags field of the SR-Capabilities sub-TLV

F-Flag:

2.2. Advertising FLC Using OSPF

[RFC8665] defines some SR Capabilities TLVs as top-level TLVs of the Router Information Opaque LSA as defined in [RFC7770]. The SR Capabilities TLVs are applicable to both OSPFv2 and OSPFv3 (see also [RFC8666]). Within the SR Capabilities TLVs, the SID/Label Range TLV has a 1-octet Reserved field. Bit 0 in the Reserved field of the SID/Label Range TLV is used as the FLC Flag (F-Flag), as shown in Figure 2.

 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|F|             |
+-+-+-+-+-+-+-+-+
Figure 2: Reserved field of the SID/Label Range TLV

F-Flag:

3. Advertising FRLD Using IGP

As requested by [RFC8491], IANA has created an IANA-managed registry titled "IGP MSD-Types" to identify MSD-Types. A new MSD-Type, called FRLD-MSD, is defined to advertise the FRLD of a given router. The MSD-Type code 3 is requested to be assigned by IANA for FRLD-MSD. The MSD-Value field is set to the FRLD in the range between 0 to 255.

If a router has multiple interfaces with different capabilities of reading the maximum label stack depth, the router MUST advertise the smallest value found across all of its interfaces.

For IS-IS, the FRLD is advertised in a Node MSD Sub-TLV [RFC8491] using the FRLD-MSD type.

For OSPF including both OSPFv2 and OSPFv3, the FRLD is advertised in a Node MSD TLV [RFC8476] using the FRLD-MSD type.

The absence of FRLD-MSD advertisements indicates only that the advertising node does not support advertisement of this capability.

4. Signaling FLC and FRLD in BGP-LS

The IGP extensions defined in this document can be advertised via BGP-LS (Distribution of Link-State and Traffic Engineering Information Using BGP) [I-D.ietf-idr-rfc7752bis] using existing BGP-LS TLVs.

The FLC is advertised using the SR Capabilities TLV as defined in [RFC9085].

The FRLD-MSD is advertised using the Node MSD TLV as defined in [RFC8814].

5. Security Considerations

This document specifies the ability to advertise additional node capabilities using IS-IS, OSPF and BGP-LS. As such, the security considerations as described in the referenced specifications are applicable to this document.

Incorrectly setting the F-Flag during origination, propagation, or redistribution may lead to poor or no performance measurement of the MPLS traffic or to the MPLS traffic being discarded on the egress node.

Incorrectly setting the FRLD value may lead to poor or no performance measurement of the MPLS traffic.

6. IANA Considerations

This document requests the following allocation from IANA:

7. Acknowledgements

The authors would like to acknowledge Acee Lindem and Les Ginsberg for their very helpful comments.

8. References

8.1. Normative References

[I-D.ietf-idr-rfc7752bis]
Talaulikar, K., "Distribution of Link-State and Traffic Engineering Information Using BGP", Work in Progress, Internet-Draft, draft-ietf-idr-rfc7752bis-16, , <https://datatracker.ietf.org/doc/html/draft-ietf-idr-rfc7752bis-16>.
[I-D.ietf-mpls-inband-pm-encapsulation]
Cheng, W., Min, X., Zhou, T., Dai, J., and Y. Peleg, "Encapsulation For MPLS Performance Measurement with Alternate Marking Method", Work in Progress, Internet-Draft, draft-ietf-mpls-inband-pm-encapsulation-06, , <https://datatracker.ietf.org/doc/html/draft-ietf-mpls-inband-pm-encapsulation-06>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC7770]
Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and S. Shaffer, "Extensions to OSPF for Advertising Optional Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, , <https://www.rfc-editor.org/info/rfc7770>.
[RFC7981]
Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions for Advertising Router Information", RFC 7981, DOI 10.17487/RFC7981, , <https://www.rfc-editor.org/info/rfc7981>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[RFC8476]
Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak, "Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476, DOI 10.17487/RFC8476, , <https://www.rfc-editor.org/info/rfc8476>.
[RFC8491]
Tantsura, J., Chunduri, U., Aldrin, S., and L. Ginsberg, "Signaling Maximum SID Depth (MSD) Using IS-IS", RFC 8491, DOI 10.17487/RFC8491, , <https://www.rfc-editor.org/info/rfc8491>.
[RFC8665]
Psenak, P., Ed., Previdi, S., Ed., Filsfils, C., Gredler, H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPF Extensions for Segment Routing", RFC 8665, DOI 10.17487/RFC8665, , <https://www.rfc-editor.org/info/rfc8665>.
[RFC8666]
Psenak, P., Ed. and S. Previdi, Ed., "OSPFv3 Extensions for Segment Routing", RFC 8666, DOI 10.17487/RFC8666, , <https://www.rfc-editor.org/info/rfc8666>.
[RFC8667]
Previdi, S., Ed., Ginsberg, L., Ed., Filsfils, C., Bashandy, A., Gredler, H., and B. Decraene, "IS-IS Extensions for Segment Routing", RFC 8667, DOI 10.17487/RFC8667, , <https://www.rfc-editor.org/info/rfc8667>.
[RFC8814]
Tantsura, J., Chunduri, U., Talaulikar, K., Mirsky, G., and N. Triantafillis, "Signaling Maximum SID Depth (MSD) Using the Border Gateway Protocol - Link State", RFC 8814, DOI 10.17487/RFC8814, , <https://www.rfc-editor.org/info/rfc8814>.
[RFC9085]
Previdi, S., Talaulikar, K., Ed., Filsfils, C., Gredler, H., and M. Chen, "Border Gateway Protocol - Link State (BGP-LS) Extensions for Segment Routing", RFC 9085, DOI 10.17487/RFC9085, , <https://www.rfc-editor.org/info/rfc9085>.

8.2. Informative References

[RFC9088]
Xu, X., Kini, S., Psenak, P., Filsfils, C., Litkowski, S., and M. Bocci, "Signaling Entropy Label Capability and Entropy Readable Label Depth Using IS-IS", RFC 9088, DOI 10.17487/RFC9088, , <https://www.rfc-editor.org/info/rfc9088>.
[RFC9089]
Xu, X., Kini, S., Psenak, P., Filsfils, C., Litkowski, S., and M. Bocci, "Signaling Entropy Label Capability and Entropy Readable Label Depth Using OSPF", RFC 9089, DOI 10.17487/RFC9089, , <https://www.rfc-editor.org/info/rfc9089>.

Authors' Addresses

Xiao Min
ZTE Corp.
Nanjing
China
Zheng(Sandy) Zhang
ZTE Corp.
Nanjing
China
Weiqiang Cheng
China Mobile
Beijing
China