Technical Summary
Bidirectional Forwarding Detection (BFD) requires that messages are
transmitted at regular intervals and provides a way to negotiate the
interval used by BFD peers. Some BFD implementations may be
restricted to only support several interval values. When such BFD
implementations speak to each other, there is a possibility of two
sides not being able to find a common value for the interval to run
BFD sessions.
This document defines a small set of interval values for BFD that we
call "Common Intervals", and recommends implementations to support
the defined intervals. This solves the problem of finding an
interval value that both BFD speakers can support while allowing a
simplified implementation as seen for hardware-based BFD. It does
not restrict an implementation from supporting more intervals in
addition to the Common Intervals.
Working Group Summary:
Discussion in the working group among known implementers of BFD
was relatively quiet but supportive of this document. The only
discussion that generated any significant amount of "noise" was the
discussion of whether these well known common intervals should
have an IANA registry to permit the maintenance of this document
without requiring a RFC revision. The consensus of that discussion
was that an IANA registry was not desired.
Document Quality:
Multiple implementations support the full range of documented values
in either hardware or software, depending on the implementation.
The only value that doesn't have very wide support is the 3.3ms value,
but support for this value seems to be becoming more common.
Personnel:
Document Shepherd: Jeffrey Haas
Responsible Area Director: Adrian Farrel