Re: draft-suping-bfd-mpls-fecmismatch-00 questions

["Thomas D. Nadeau" <[e-mail]>]

On Feb 25, 2005, at 8:41 PM, zhaisuping wrote:

> Hi, all
> The purpose of FEC filter in BFD is to detect the consistence of
> the control plane and data plane. So that in the MPLS network, just
> running the BFD session(LSP-Ping is not needed) is enough for the
> defect detection. Or else such tools as LSP-Ping is needed because
> the BFD session can't detect the inconsistence of the control plane
> and data plane.

	There are cases where BFD/MPLS will work and return
a positive result, but the LSP is actually broken.
If you run LSP ping, this will certainly detect (and report) the
failure.  This is why a combination of both tools is necessary.
BFD with or without your FEC filter will not solve all of the
problems alone.

	--Tom


> In the section 2 of the draft, there is description of the
> problem the draft want to solve.
>>> Wouldn't LSP-Ping (or VCCV) be a more appropriate place to do this
>>> filter verification?
>
>
>>
>> LSP-Ping does a verification on the FEC itself, so a filter would add
>> nothing.
>>
>> VCCV is not a protocol.  Just a little sideband for sending IP packets
>> down a pseudowire so that you can run LSP-Ping, BFD, etc. between the
>> two ends.
>>
>> ....George
>>
>> ====================================================================== 
>> ==
>> George Swallow             Cisco Systems                  (978)  
>> 936-1398
>>                           1414 Massachusetts Avenue
>>                           Boxborough, MA 01719
>