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Document: draft-ietf-idr-bfd-subcode-04
Reviewer: Elwyn Davies
Review Date: 2022-11-18
IETF LC End Date: 2022-11-15
IESG Telechat date: 2022-12-01

Summary: Ready with nits. There are a number of places where additional refereences would be helpful and the introduction doesn't say what it is going to do to solve the identified problem. 

Major issues:
None

Minor issues:
None

Nits/editorial comments:
Abstract:  Please include references to the BFD protocol specification [RFC 5880].

Abstract, para 2:
OLD:
   This document defines a Subcode for the BGP Cease NOTIFICATION
   message for when a BGP connection is being closed due to a BFD
   session going down.
NEW:
   This document defines a Subcode for the BGP Cease NOTIFICATION
   message [RGC 4271, Section 6.7] for use when a BGP connection is 
   being closed due to a BFD session going down.
END

S1, para 3:
OLD:
   If a BGP speaker desires to have its connections terminate faster
   than the negotiated BGP Hold Timer can accommodate upon loss of
   connectivity with a neighbor, the BGP speakers can rely upon BFD is
   used to supply that faster detection. When the BFD session state
   changes to Down, the BGP speaker terminates the connection with a
   NOTIFICATION message sent to the neighbor, if possible, and then
   close the TCP connection for the connection.

NEW:
   If a BGP speaker desires to have its connections terminate more quickly
   than the negotiated BGP Hold Timer can accommodate upon loss of
   connectivity with a neighbor, the BFD protocol can be relied upon by BGP 
   speakers to detect the loss of connectivity more rapidly. When the BFD 
   session state changes to Down, the BGP speaker terminates the connection 
   with a Cease NOTIFICATION message sent to the neighbor, if possible, and 
   may then close the TCP session for the connection.

   This document defines a subcode "BFD Down" to be sent with the Cease NOTIFICATION 
   message that indicates the reason for this type of connection termination. 
ENDS

s3, last para: s/it may not be possible/it may not have been possible/

s5: s/Reference of this document/reference to this document/

s5: It would be useful to provide a reference to the relevant IANA registry
https://www.iana.org/assignments/bgp-parameters/bgp-parameters.xhtml#bgp-parameters-8

s7: Arguably I would say RFC 4482 should be a normative reference.