[c-nsp] Cisco BFD and NSF

[David J. Hughes]

On 31/07/2006, at 4:38 PM, Saku Ytti wrote:

> On (2006-07-31 09:04 +1000), David J. Hughes wrote:
>
>> Wow, that's a major disappointment.  So much for BFD being
>> implemented in the forwarding plane.
>
> How would this work? If BFD was off-loaded to linecards? Linecards  
> would
> just send 'down event' to control-plane when BFD goes down in  
> particular
> linecard? And 'show bfd ...' would actually poll real status from each
> line card every time executed?

If you have a read of all the original papers on BFD (Katz etc)  it's  
almost a design premise that it's NOT implemented in the RP.   A  
paper that Dave Katz and Dave Ward gave at NANOG states :

---
What is BFD?

Low-overhead, short-duration detection of failures in
the path between adjacent forwarding engines,
including the interfaces, data link(s), and forwarding
planes

Implemented in forwarding engine of the system,
where forwarding and control engines are separated

Decouples the protocol from the fate of the RP
and thus, very useful for GR verification
---

As for an RP's ability to detect the failure of a linecard, that's a  
different question in my opinion.   A very important question but  
different none the less.


David
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