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Bidirectional Forwarding Detection

The information below is for an older proposed charter
Document Proposed charter Bidirectional Forwarding Detection WG (bfd) Snapshot
Title Bidirectional Forwarding Detection
Last updated 2013-12-06
State Start Chartering/Rechartering (Internal Steering Group/IAB Review) Rechartering
WG State Active
IESG Responsible AD John Scudder
Charter edit AD Adrian Farrel
Send notices to (None)

The BFD Working Group is chartered to standardize and support the
bidirectional forwarding detection protocol (BFD) and its extensions.  A
core goal of the working group is to standardize BFD in the context of 
IP routing, or protocols such as MPLS that are based on IP routing, in a 
way that will encourage multiple, inter-operable vendor implementations.  
The Working Group will also provide advice and guidance on BFD to other 
working groups or standards bodies as requested.

BFD is a protocol intended to detect faults in the bidirectional path
between two forwarding engines, including physical interfaces,
subinterfaces, data link(s), and to the extent possible the forwarding
engines themselves, with potentially very low latency. It operates
independently of media, data protocols, and routing protocols. An
additional goal is to provide a single mechanism that can be used for
liveness detection over any media, at any protocol layer, with
a wide range of detection times and overhead, to avoid a proliferation
of different methods.

Important characteristics of BFD include:

- Simple, fixed-field encoding to facilitate implementations in 

- Independence of the data protocol being forwarded between two systems.
  BFD packets are carried as the payload of whatever encapsulating 
  protocol is appropriate for the medium and network.

- Path independence: BFD can provide failure detection on any kind of 
  path between systems, including direct physical links, virtual 
  circuits, tunnels, MPLS LSPs, multihop routed paths, and 
  unidirectional links (so long as there is some return path, of 

- Ability to be bootstrapped by any other protocol that automatically 
  forms peer, neighbor or adjacency relationships to seed BFD endpoint 

The working group is chartered to complete the following work items:

1. Develop the MIB module for BFD and submit it to the IESG for 
publication as a Proposed Standard.

2a. Provide a generic keying-based cryptographic authentication 
mechanism for the BFD protocol in discussion with the KARP working 
group.  This mechanism  will support authentication through a key 
identifier for the BFD session's Security Association rather than 
specifying new authentication extensions.  

2b. Provide extensions to the BFD MIB in support of the generic keying-
based cryptographic authentication mechanism.

2c. Specify cryptographic authentication procedures for the BFD protocol
using HMAC-SHA-256 (possibly truncated to a smaller integrity check 
value but not beyond commonly accepted lengths to ensure security) using 
the generic keying-based cryptographic authentication mechanism.

3. Provide an extension to the BFD core protocol in support of point-to-
multipoint links and networks.

4. Assist the MPLS working group in the standardization of the BFD 
protocol for MPLS-TP.  The preferred solution will be interoperable with 
the current BFD specification.

5. Provide one or more mechanisms to run BFD over Link Aggregation Group

6. Provide an informational document to recommend standardized timers 
and timer operations for BFD when used in different applications.

The working group will maintain a relationship with the KARP and MPLS 
working groups, and will communicate with the IEEE with respect to BFD
over LAGs.