Internet DRAFT - draft-liu-lsr-mpls-inspection-msd
draft-liu-lsr-mpls-inspection-msd
LSR Y. Liu
Internet-Draft ZTE
Intended status: Standards Track 6 March 2023
Expires: 7 September 2023
Signaling Base MPLS Inspection MSD
draft-liu-lsr-mpls-inspection-msd-00
Abstract
This document defines a new type of MSD, Base MPLS Inspection MSD,
and the mechanism to signal this MSD 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.
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This Internet-Draft will expire on 7 September 2023.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions Used in This Document . . . . . . . . . . . . . . 3
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 3
3. Base MPLS Inspection MSD . . . . . . . . . . . . . . . . . . 3
4. Advertising Base MPLS Inspection MSD Using IS-IS . . . . . . 3
5. Advertising Base MPLS Inspection MSD Using OSPF . . . . . . . 4
6. Signaling Base MPLS Inspection MSD in BGP-LS . . . . . . . . 4
7. Security Considerations . . . . . . . . . . . . . . . . . . . 4
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
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.
[I-D.ietf-mpls-mna-hdr] defines the MPLS Network Action sub-
stack(NAS) solution for carrying Network Actions and Ancillary Data
in the label stack. The node adding an NAS to the label stack will
need to place a copy of the NAS where it can be read by the relevant
nodes. A node that pushes a NAS onto the label stack is responsible
for determining that all nodes that should process the NAS will have
the NAS within its Maximum MPLS Stack Inspection depth. A node
should use signaling to determine this.
On the other hand, even if the MNA framework is not followed, as long
as there're scenarios where every transit node is required to inspect
beyond the top of stack, the requirement to obtain the maximum
inspection depth of the nodes along the LSP exists.
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, Base MPLS Inspection MSD,
and the mechanism to signal this MSD using IGP and BGP-LS.
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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.
2.2. Abbreviations
MNA: MPLS Network Actions
NAS: Network Action sub-stack
EL: Entropy Label
ERLD: Entropy Readable Label Depth
3. Base MPLS Inspection MSD
The Base MPLS Inspection MSD is defined as the maximum number of
labels a router can read in an MPLS packet received on its incoming
interface(s) (starting from the top of the stack).
The Base MPLS Inspection MSD MAY be used by ingress LSRs to determine
the position of the NAS, and whether it's necessary to insert
multiple NAS at different positions in the label stack. When the
label stack are determined by a centralized controller, the MSD of
each intermediate LSR SHOULD be sent to the controller.
With Base MPLS Inspection MSD, application/network action-specified
MSD analogous to ERLD-MSD[RFC9088] [RFC9089] MAY not needed. For
example, a node can signal certain network action capability and the
Base MPLS Inspection MSD to indicate that it can process this network
action within the MSD.
4. Advertising Base MPLS Inspection MSD Using IS-IS
A new MSD-Type [RFC8491], called Base MPLS Inspection 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.
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 its interfaces.
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The absence of Base MPLS Inspection MSD advertisements indicates only
that the advertising node does not support advertisement of this
capability.
If the Base MPLS Inspection MSD type is received in the Link MSD sub-
TLV, it MUST be ignored.
5. Advertising Base MPLS Inspection MSD Using OSPF
The Base MPLS Inspection MSD is advertised in a Node MSD TLV
[RFC8476] using the same MSD-Type code as defined in section 4.
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 its interfaces.
The absence of Base MPLS Inspection MSD advertisements indicates only
that the advertising node does not support advertisement of this
capability.
If the Base MPLS Inspection MSD type is received in the Link MSD sub-
TLV, it MUST be ignored.
6. Signaling Base MPLS Inspection MSD in BGP-LS
The IS-IS and OSPF 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 Base MPLS Inspection MSD is advertised using the Node MSD TLV as
defined in [RFC8814].
7. 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 ERLD value may lead to poor or no
execution of the network action.
8. IANA Considerations
This document requests the following allocation from IANA:
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Type TBA in the IGP MSD-Types registry is requested to be assigned
for the Base MPLS Inspection MSD.
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>.
[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>.
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[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>.
[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-02, 21 October 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-mpls-
mna-fwk-02>.
[I-D.ietf-mpls-mna-hdr]
Rajamanickam, J., Gandhi, R., Zigler, R., Song, H., and K.
Kompella, "MPLS Network Action (MNA) Sub-Stack Solution",
Work in Progress, Internet-Draft, draft-ietf-mpls-mna-hdr-
00, 2 March 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-mpls-mna-hdr-00>.
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[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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