Internet DRAFT - draft-dubrovsky-bess-evpn-next-hop
draft-dubrovsky-bess-evpn-next-hop
Internet Engineering Task Force M. Dubrovsky
Internet-Draft Cisco
Updates: 7432 (if approved) 3 September 2022
Intended status: Standards Track
Expires: 7 March 2023
EVPN Next Hop address encoding
draft-dubrovsky-bess-evpn-next-hop-00
Abstract
This document clarifies that the EVPN route Next Hop encoding is
unaffected by whether the underlying BGP session is IPv4 or IPv6.
From that perspective, this document updates the EVPN specification
to provide more comprehensive documentation of the encoding.
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
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This Internet-Draft will expire on 7 March 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
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Please review these documents carefully, as they describe your rights
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provided without warranty as described in the Revised BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 2
3. EVPN MP_REACH_NLRI Next Hop encoding . . . . . . . . . . . . 2
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 3
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 3
6.1. Normative References . . . . . . . . . . . . . . . . . . 3
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
For operational simplicity, a network administrator can choose to
enable multiple AFI/SAFI over a single BGP session.
While [RFC7432] specifies that the Next Hop field of the
MP_REACH_NLRI attribute can be set to the IPv4 or IPv6 address for
EVPN routes, it does not clarify the exact encoding when the address
family of a BGP session does not match the address family of the EVPN
Next Hop address.
For the sake of interoperability, this document specifies the
encoding and therefore, updates [RFC7432]. EVPN implementations MUST
conform to the prescribed encoding.
2. Requirements Language
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.
3. EVPN MP_REACH_NLRI Next Hop encoding
EVPN MP_REACH_NLRI can be advertised with either IPv4 or IPv6 next
hop.
EVPN MP_REACH_NLRI IPv4 Next Hop encoding:
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+--------------------------------------------+
| ... |
+--------------------------------------------+
| Length of Next Hop Address = 4 |
+--------------------------------------------+
| Network Address of Next Hop = IPv4 address |
+--------------------------------------------+
| ... |
+--------------------------------------------+
Table 1: EVPN MP_REACH_NLRI IPv4 next Hop
encoding
EVPN MP_REACH_NLRI IPv6 next Hop encoding:
+--------------------------------------------+
| ... |
+--------------------------------------------+
| Length of Next Hop Address = 16 |
+--------------------------------------------+
| Network Address of Next Hop = IPv6 address |
+--------------------------------------------+
| ... |
+--------------------------------------------+
Table 2: EVPN MP_REACH_NLRI IPv6 next Hop
encoding
The above encoding is done regardless of whether the BGP session is
running over IPv4 or IPv6.
4. IANA Considerations
This memo includes no request to IANA.
5. Security Considerations
This document should not affect the security of the Internet.
6. References
6.1. 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>.
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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>.
[RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February
2015, <https://www.rfc-editor.org/info/rfc7432>.
Acknowledgements
The author would like to thank Aamod Vyavaharkar and Kyuhwan Kim for
their helpful feedback.
Author's Address
Mike Dubrovsky
Cisco
Email: mdubrovs@cisco.com
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