RFC 5549, "Advertising IPv4 Network Layer Reachability Information with an IPv6 Next Hop", May 2009

Note: This RFC has been obsoleted by RFC 8950

Errata ID: 6786
Status: Reported
Type: Technical
Publication Format(s) : TEXT
Reported By: Mike Dubrovsky
Date Reported: 2021-12-17

Section 4 says:

   A BGP speaker MUST only advertise to a BGP peer the IPv4 or VPN-IPv4
   NLRI with an IPv6 Next Hop if the BGP speaker has first ascertained
   via BGP Capability Advertisement that the BGP peer supports the
   Extended Next Hop Encoding capability for the relevant AFI/SAFI pair.

It should say:

   A BGP speaker MUST only advertise to a BGP peer the IPv4 or VPN-IPv4
   NLRI with an IPv6 Next Hop if the BGP speaker has first ascertained
   via BGP Capability Advertisement that the BGP peer supports the
   Extended Next Hop Encoding capability for the relevant AFI/SAFI pair.
   
   IPv4 or VPN-IPv4 NLRI with an IPv6 Next Hop SHOULD be treated as 
   malformed if it received from a BGP speaker that has not sent BGP 
   Capability Advertisement for the relevant AFI/SAFI pair.   

Notes:

The behavior was not explicitly mentioned.

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