[c-nsp] Using BFD as a link monitoring protocol

[Oliver Boehmer (oboehmer)]

Hi,

>  I need to monitor the state of links between router interfaces, and I
have
> a case where the link may go down (due to fibre break at L2) but the
> interfaces still appear up when polled (we're on a ring). When a link
goes
> down I need to get sent a trap specifically identifying which link
went
> down, so I've looked at BFD (Bidirectional Forwarding Detection), and
the
> idea is to set up bfd sessions to run between each pair of interfaces
that
> define a link, and a session failure will result in snmp traps being
sent
> identifying which link failed.
> 
> My question is: Has anyone deployed BFD for this purpose, i.e link
failure
> monitoring, and is this an appropriate application of BFD?

Well, you can't just run BFD by itself, you need to have an
application/client (routing protocols, HSRP, etc.) which is configured
to use BFD before BFD establishes a session (not sure if the hidden
command "bfd neighbor x.x.x.x" can work around this).
In addition, BFD MIB is not yet there except in 12.2SRE.

Not sure how many pairs you need to monitor, but you could investigate
using IP-SLA probes for this purpose..

	oli