Internet DRAFT - draft-liu-lsr-mpls-inspection-msd
draft-liu-lsr-mpls-inspection-msd
LSR Y. Liu
Internet-Draft ZTE
Intended status: Standards Track 18 September 2023
Expires: 21 March 2024
Signaling MPLS Readable Label Depth(RLD)
draft-liu-lsr-mpls-inspection-msd-04
Abstract
This document defines a new type of MSD to reflect the Readable Label
Depth(RLD), and the mechanism to signal this MSD using IGP and BGP-
LS.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 21 March 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 2
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
3. RLD MSD . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Advertising RLD MSD Using IGP . . . . . . . . . . . . . . . . 3
5. Signaling Base MPLS Inspection MSD in BGP-LS . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 4
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 4
9.1. Normative References . . . . . . . . . . . . . . . . . . 4
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
[I-D.ietf-mpls-mna-fwk] specifies an architectural framework for the
MPLS Network Actions (MNA) technologies. MNA technologies are used
to indicate actions for Label Switched Paths (LSPs) and/or MPLS
packets and to transfer data needed for these actions. And an MNA
solution is envisioned as a set of network action sub-stacks(NAS),
plus possible post-stack data. In order to put the NAS(s) at the
appropriate place into the MPLS label stack, [I-D.ietf-mpls-mna-fwk]
introduces the concept of Readable Label Depth(RLD), and puts forward
the need for signaling of RLD via MPLS signaling protocols.
Maximum SID Depth (MSD)[RFC8491] is originally introduced for SR-MPLS
to express the number of SIDs supported by a node or a link on a
node. In a non-SR MPLS network, MSD defines the maximum label depth.
This document defines a new type of MSD for RLD, and the mechanism to
signal this MSD using IGP and BGP-LS.
2. Conventions Used in This Document
2.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119] [RFC8174]
when, and only when, they appear in all capitals, as shown here.
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2.2. Abbreviations
MNA: MPLS Network Actions
NAS: Network Action ub-stack
EL: Entropy Label
ERLD: Entropy Readable Label Depth
RLD: Readable Label Depth
3. RLD MSD
The RLD MSD MAY be used by NAS imposing node to determine the
position of the NAS. When the label stacks are determined by a
centralized controller, the RLD MSD of each intermediate LSR SHOULD
be sent to the controller.
With RLD MSD, new application/network action-specified MSDs analogous
to ERLD-MSD[RFC9088] [RFC9089] MAY not be needed. For example, a
node can signal certain network action capability and the RLD MSD to
indicate that it can process this network action within the MSD.
Editor's note: The reason why ERLD-MSD is not reused to reflect the
RLD is that the definition of ERLD is strongly related the router's
ability to process entropy label. As specified in [RFC8662], the
ERLD means that the router will perform load-balancing using the EL
if the EL is placed within the first ERLD labels, and a router
capable of reading N labels but not using an EL located within those
N labels MUST consider its ERLD to be 0. Considering that
implementations in strict accordance with the definition of ERLD may
exist, defining a new MSD instead of reusing/updating ERLD is
preferred in this document.
4. Advertising RLD MSD Using IGP
A new IGP MSD-Type, called RLD MSD, is defined. The MSD-Type code is
to be assigned by IANA. The MSD-Value field is set to the maximum
number of labels a router can read in the range between 0 to 255.
The scope of the advertisement depends on the application. This MSD
can be advertised on the per-node and/or per-link basis as in IS-IS
[RFC8491] and OSPF [RFC8476].
The absence of RLD MSD advertisements indicates only that the
advertising node does not support advertisement of this capability.
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5. Signaling Base MPLS Inspection MSD 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 RLD MSD is advertised via the Node MSD TLV and/or the Link MSD
TLV as defined in [RFC8814].
6. 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 [RFC5340], [RFC7684], [RFC7752],
[RFC7770], [RFC7794], [RFC7981], [RFC8476], [RFC8491], [RFC8662],
[RFC8814], [RFC9085] are applicable to this document.
Incorrectly setting of the RLD MSD value may lead to poor or no
execution of the network action.
7. IANA Considerations
This document requests the following allocation from IANA:
Type TBA in the IGP MSD-Types registry is requested to be assigned
for RLD MSD.
8. Acknowledgement
The author would like to thank Greg Mirsky, Les Ginsberg, Tony Li and
Gyan Mishra for their helpful review and comments.
9. References
9.1. 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>.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
<https://www.rfc-editor.org/info/rfc5340>.
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[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, November
2015, <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, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[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,
February 2016, <https://www.rfc-editor.org/info/rfc7770>.
[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,
March 2016, <https://www.rfc-editor.org/info/rfc7794>.
[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>.
[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>.
[RFC8476] Tantsura, J., Chunduri, U., Aldrin, S., and P. Psenak,
"Signaling Maximum SID Depth (MSD) Using OSPF", RFC 8476,
DOI 10.17487/RFC8476, December 2018,
<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, November 2018,
<https://www.rfc-editor.org/info/rfc8491>.
[RFC8662] Kini, S., Kompella, K., Sivabalan, S., Litkowski, S.,
Shakir, R., and J. Tantsura, "Entropy Label for Source
Packet Routing in Networking (SPRING) Tunnels", RFC 8662,
DOI 10.17487/RFC8662, December 2019,
<https://www.rfc-editor.org/info/rfc8662>.
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[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, August 2020,
<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, August 2021,
<https://www.rfc-editor.org/info/rfc9085>.
9.2. Informative References
[I-D.ietf-mpls-mna-fwk]
Andersson, L., Bryant, S., Bocci, M., and T. Li, "MPLS
Network Actions Framework", Work in Progress, Internet-
Draft, draft-ietf-mpls-mna-fwk-04, 5 September 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-mpls-
mna-fwk-04>.
[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, August 2021,
<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, August 2021,
<https://www.rfc-editor.org/info/rfc9089>.
Author's Address
Yao Liu
ZTE
Nanjing
China
Email: liu.yao71@zte.com.cn
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