[bess] [Technical Errata Reported] RFC9721 (9001)

rfc-editor@rfc-editor.org Thu, 11 June 2026 18:04 UTC

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To: james.n.guichard@futurewei.com, apjoshi@cisco.com, jorge.rabadan@nokia.com, gunter.van_de_velde@nokia.com, ketant.ietf@gmail.com, sajassi@gmail.com, nmalhotr@cisco.com, jdrake@juniper.net, slitkows.ietf@gmail.com, gunter@vandevelde.cc, ar977m@att.com
Date: Thu, 11 Jun 2026 18:04:54 -0000
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CC: rfc-editor@rfc-editor.org, anarayanan@arista.com, bess@ietf.org
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Subject: [bess] [Technical Errata Reported] RFC9721 (9001)
Archived-At: <https://mailarchive.ietf.org/arch/msg/bess/rrMP_7VXNlpeTLSu0KRS3YUCQWw>

The following errata report has been submitted for RFC9721,
"Extended Mobility Procedures for Ethernet VPN Integrated Routing and Bridging (EVPN-IRB)"

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You may review the report below and at:
https://errata.rfc-editor.org/eid9001/

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Type: Technical
Reported by: Anand Narayanan <anarayanan@arista.com>

Section Abstract says:

Original Text
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The extensions are backward compatible with existing EVPN-IRB implementations and aim to optimize network performance in scenarios involving frequent IP address mobility.

Corrected Text
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The extensions while backwards incompatible, allow EVPN-IRB implementations to deterministically handle scenarios involving frequent IP address mobility

Notes
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The mobility procedures defined in RFC9721 does not seem backwards compatible with the procedures defined in RFC7432.

Example:

Premise:

1. An RFC7432 speaker has MAC Mx with sequence number = 1
2. An RFC9721 speaker has MAC My with sequence number = 2

Sequence of Events:

1. The RFC9721 speaker learns a local ARP for IPx-My, and advertised MAC-IP route with sequence number 2
2. IPx moves to be behind RFC7432 speaker
3. RFC7432 speaker would simply advertise IPx-Mx with sequence number 1
4. When RFC9721 speaker receives the MAC-IP route advertised by RFC7432 for IPx-Mx, it will be unable to remove it's local ARP binding because the remote route has an inferior sequence number.

This makes the schemes not compatible with each other.

Instructions:
-------------
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RFC9721 (draft-ietf-bess-evpn-irb-extended-mobility)
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Title : Extended Mobility Procedures for Ethernet VPN Integrated Routing and Bridging (EVPN-IRB)
Publication Date : April 2025
Author(s) : N. Malhotra, Ed., A. Sajassi, A. Pattekar, J. Rabadan, A. Lingala, J. Drake
Category : Proposed Standard
Source : bess (rtg)
Stream : IETF
Verifying Party : IESG

[bess] [Technical Errata Reported] RFC9721 (9001) rfc-editor