Internet-Draft Signaling FLC and FLRD using IGP and BGP August 2021
Min, et al. Expires 19 February 2022 [Page]
Workgroup:
LSR Working Group
Internet-Draft:
draft-xzc-lsr-mpls-flc-flrd-01
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 Using IGP and BGP-LS

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 19 February 2022.

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

Even though FLC is a property of the node, in some cases it is advantageous to associate and advertise the FLC with a prefix, so FLC is advertised with a prefix in this document.

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

If the router supports FLs on all of its interfaces, it SHOULD advertise the FLC with every local host prefix it advertises in IGP.

2.1. Advertising FLC Using IS-IS

Next to the ELC Flag (E-flag) defined in Section 3 of [RFC9088], a new bit FLC Flag (F-flag) is defined, which is Bit 4 in the Prefix Attribute Flags [RFC7794], as shown in Figure 1.

   0 1 2 3 4 5 6 7...
  +-+-+-+-+-+-+-+-+...
  |X|R|N|E|F|      ...
  +-+-+-+-+-+-+-+-+...
Figure 1: Prefix Attribute Flags

F-Flag: FLC Flag (Bit 4)

The FLC signaling MUST be preserved when a router propagates a prefix between ISIS levels [RFC5302].

2.2. Advertising FLC Using OSPFv2

Next to the ELC Flag (E-flag) defined in Section 3.1 of [RFC9089], a new bit FLC Flag (F-flag) is defined, which is Bit 3 in Flags field of OSPFv2 Extended Prefix TLV [RFC7684]:

The FLC signaling MUST be preserved when an OSPFv2 Area Border Router (ABR) distributes information between areas. To do so, an ABR MUST originate an OSPFv2 Extended Prefix Opaque LSA [RFC7684] including the received FLC setting.

2.3. Advertising FLC Using OSPFv3

Next to the ELC Flag (E-flag) defined in Section 3.2 of [RFC9089], a new bit FLC Flag (F-flag) is defined, which is Bit 0 in OSPFv3 PrefixOptions field [RFC5340]:

The FLC signaling MUST be preserved when an OSPFv3 Area Border Router (ABR) distributes information between areas. The setting of the FLC Flag in the Inter-Area-Prefix-LSA [RFC5340] or in the Inter-Area-Prefix TLV [RFC8362], generated by an ABR, MUST be the same as the value the FLC Flag associated with the prefix in the source area.

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 TE Information Using BGP) [RFC7752] using existing BGP-LS TLVs.

The FLC is advertised using the Prefix Attribute Flags TLV as defined in [RFC9085].

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

5. Security Considerations

This document does not raise any additional security issues beyond those of the specifications referred to in the list of normative references.

6. IANA Considerations

This document requests the following allocations from IANA:

7. Acknowledgements

TBA.

8. Normative References

[I-D.ietf-mpls-inband-pm-encapsulation]
Cheng, W., Min, X., Zhou, T., Dong, X., and Y. Peleg, "Encapsulation For MPLS Performance Measurement with Alternate Marking Method", Work in Progress, Internet-Draft, draft-ietf-mpls-inband-pm-encapsulation-01, , <https://www.ietf.org/archive/id/draft-ietf-mpls-inband-pm-encapsulation-01.txt>.
[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>.
[RFC5302]
Li, T., Smit, H., and T. Przygienda, "Domain-Wide Prefix Distribution with Two-Level IS-IS", RFC 5302, DOI 10.17487/RFC5302, , <https://www.rfc-editor.org/info/rfc5302>.
[RFC5340]
Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, DOI 10.17487/RFC5340, , <https://www.rfc-editor.org/info/rfc5340>.
[RFC7684]
Psenak, P., Gredler, H., Shakir, R., Henderickx, W., Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute Advertisement", RFC 7684, DOI 10.17487/RFC7684, , <https://www.rfc-editor.org/info/rfc7684>.
[RFC7752]
Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and S. Ray, "North-Bound Distribution of Link-State and Traffic Engineering (TE) Information Using BGP", RFC 7752, DOI 10.17487/RFC7752, , <https://www.rfc-editor.org/info/rfc7752>.
[RFC7794]
Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, , <https://www.rfc-editor.org/info/rfc7794>.
[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>.
[RFC8362]
Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and F. Baker, "OSPFv3 Link State Advertisement (LSA) Extensibility", RFC 8362, DOI 10.17487/RFC8362, , <https://www.rfc-editor.org/info/rfc8362>.
[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>.
[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>.
[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