Internet DRAFT - draft-ietf-mpls-rfc8287-len-clarification
draft-ietf-mpls-rfc8287-len-clarification
Network Work group N. Nainar
Internet-Draft C. Pignataro
Updates: 8287 (if approved) Cisco Systems, Inc.
Intended status: Standards Track F. Iqbal
Expires: February 9, 2020 Individual
A. Vainshtein
ECI Telecom
August 8, 2019
RFC8287 Sub-TLV Length Clarification
draft-ietf-mpls-rfc8287-len-clarification-04
Abstract
RFC8287 defines the extensions to MPLS LSP Ping and Traceroute for
Segment Routing IGP-Prefix and IGP-Adjacency Segment Identifier
(SIDs) with an MPLS data plane. RFC8287 proposes 3 Target FEC Stack
Sub-TLVs. While the standard defines the format and procedure to
handle those Sub-TLVs, it does not sufficiently clarify how the
length of the Segment ID Sub-TLVs should be computed to include in
the Length field of the Sub-TLVs which may result in interoperability
issues.
This document updates RFC8287 by clarifying the length of each
Segment ID Sub-TLVs defined in RFC8287.
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
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 9, 2020.
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Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Requirements notation . . . . . . . . . . . . . . . . . . . . 3
4. Length field clarification for Segment ID Sub-TLVs . . . . . 3
4.1. IPv4 IGP-Prefix Segment ID Sub-TLV . . . . . . . . . . . 3
4.2. IPv6 IGP-Prefix Segment ID Sub-TLV . . . . . . . . . . . 3
4.3. IGP-Adjacency Segment ID Sub-TLV . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 5
9. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
[RFC8287] defines the extensions to MPLS LSP Ping and Traceroute for
Segment Routing IGP-Prefix and IGP-Adjacency Segment Identifier
(SIDs) with an MPLS data plane. [RFC8287] proposes 3 Target FEC
Stack Sub-TLVs. While the standard defines the format and procedure
to handle those Sub-TLVs, it does not sufficiently clarify how the
length of the Segment ID Sub-TLVs should be computed to include in
the Length field of the Sub-TLVs which may result in interoperability
issues.
This document updates [RFC8287] by clarifying the length of each
Segment ID Sub-TLVs defined in [RFC8287].
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2. Terminology
This document uses the terminologies defined in [RFC8402], [RFC8029],
[RFC8287] and so the readers are expected to be familiar with the
same.
3. Requirements notation
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.
4. Length field clarification for Segment ID Sub-TLVs
Section 5 of [RFC8287] defines 3 different Segment ID Sub-TLVs that
will be included in Target FEC Stack TLV defined in [RFC8029]. The
length of each Sub-TLVs MUST be calculated as defined in this
section.
The TLVs representation defined in section 5.1, 5.2 and 5.3 of
[RFC8287] are updated to clarify the length calculation as shown in
section 4.1, 4.2 and 4.3 respectively. The updated TLV
representation contain explicitly defined length.
4.1. IPv4 IGP-Prefix Segment ID Sub-TLV
The Sub-TLV length for IPv4 IGP-Prefix Segment ID MUST be set to 8 as
shown in the below TLV 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 = 34 (IPv4 IGP-Prefix SID)| Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Prefix Length | Protocol | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.2. IPv6 IGP-Prefix Segment ID Sub-TLV
The Sub-TLV length for IPv6 IGP-Prefix Segment ID MUST be set to 20
as shown in the below TLV format:
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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 = 35 (IPv6 IGP-Prefix SID)| Length = 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| IPv6 Prefix |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Prefix Length | Protocol | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.3. IGP-Adjacency Segment ID Sub-TLV
The Sub-TLV length for IGP-Adjacency Segment ID varies depending on
the Adjacency Type and Protocol. In any of the allowed combination
of Adjacency Type and Protocol, the sub-TLV length MUST be calculated
by including 2 octets of Reserved field. Table 1 below list the
length for different combinations of Adj.Type and Protocol.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Protocol | Length for Adj.Type |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Parallel | IPv4 | IPv6 | Unnumbered|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OSPF | 20 | 20 | 44 | 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ISIS | 24 | 24 | 48 | 24 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Any | 20 | 20 | 44 | 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Table 1. IGP-Adjacency SID Length Comparison
For example, when the Adj. Type is set to Parallel Adjacency and the
Protocol is set to 0, the Sub-TLV will be as below:
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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 = 36 (IGP-Adjacency SID) | Length = 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Adj. Type = 1 | Protocol = 0 | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Interface ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote Interface ID (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Node Identifier (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiving Node Identifier (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5. IANA Considerations
This document does not introduce any IANA consideration.
6. Security Considerations
This document updates [RFC8287] and does not introduce any additional
security considerations.
7. Contributors
The below individuals contributed to this document:
Zafar Ali, Cisco Systems, Inc.
8. Acknowledgement
The authors would like to thank Michael Gorokhovsky and Manohar
Doppalapudi for investigating the interop issue during EANTC test.
9. 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>.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029,
DOI 10.17487/RFC8029, March 2017,
<https://www.rfc-editor.org/info/rfc8029>.
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[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>.
[RFC8287] Kumar, N., Ed., Pignataro, C., Ed., Swallow, G., Akiya,
N., Kini, S., and M. Chen, "Label Switched Path (LSP)
Ping/Traceroute for Segment Routing (SR) IGP-Prefix and
IGP-Adjacency Segment Identifiers (SIDs) with MPLS Data
Planes", RFC 8287, DOI 10.17487/RFC8287, December 2017,
<https://www.rfc-editor.org/info/rfc8287>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
Authors' Addresses
Nagendra Kumar Nainar
Cisco Systems, Inc.
7200-12 Kit Creek Road
Research Triangle Park, NC 27709
US
Email: naikumar@cisco.com
Carlos Pignataro
Cisco Systems, Inc.
7200-11 Kit Creek Road
Research Triangle Park, NC 27709
US
Email: cpignata@cisco.com
Faisal Iqbal
Individual
Canada
Email: faisal.iqbal@msn.com
Alexander Vainshtein
ECI Telecom
Israel
Email: vainshtein.alex@gmail.com
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