Catalyst 9500 - BFD hardware offload - how to?

[jesper_petersen]

Hi all

Does anyone know how to go about getting BFD offloaded in hardware on the Cat9500 platform?

More specifically we're talking about the C9500-24Q device.

We're currently using BFD, but everything is handled in software as per the output of the "sh bfd neighbors details":

IPv4 Sessions
NeighAddr LD/RD RH/RS State Int
10.10.x.x 5/1124073485 Up Up Fo1/0/11
Session state is UP and using echo function with 100 ms interval.
Session Host: Software
OurAddr: 10.10.x.x

I am not able to find any solid documentation on this - I even have doubts if it is even possible on this platform - although I presume that it is.

Anyone have any experience or something else that can point me in the right direction?

Thank you in advance. 

[Joseph W. Doherty]

Hmm, I thought, if platform's hardware supports BFD it was "automatic".  Cannot think of a reason why platform would do it in software, if hardware supported, beyond, perhaps, for debugging purposes.

We'll see if anyone else knows for sure.

[Giuseppe Larosa]

Hello @jesper_petersen ,

see the following presentation

https://www.ciscolive.com/c/dam/r/ciscolive/us/docs/2019/pdf/BRKARC-2007.pdf

see slide 16 there are multiple ASICs handling different sets of ports , but this does mean that this is  a fully distributed platform like an ASR 9000 or like an old Catalyst 6500/6800.

BFD is a simple protocol but it  requires a CPU to be processed.

Hope to help

Giuseppe

[jesper_petersen]

Hi @Giuseppe Larosa 

Thank you for your reply. 

You're right that it will involve the CPU at some stages during operation, initial setup, when a BFD event triggers, etc.

I guess what I'm seeking is to know for a fact that the BFD packets during normal operation are generated and handled in hardware and not by the CPU. Only when an event triggers will the CPU be interrupted and involved.