bfd-like mechanism for LANPHY connections between providers

Jensen Tyler JTyler at
Wed Mar 16 15:42:39 CDT 2011

Correct me if I am wrong but to detect a failure by default BGP would wait the "hold-timer" then declare a peer dead and converge.

So you would be looking at 90 seconds(juniper default?) + CPU bound convergence time to recover? Am I thinking about this right?

-----Original Message-----
From: Jeff Wheeler [mailto:jsw at] 
Sent: Wednesday, March 16, 2011 1:55 PM
To: nanog at
Subject: Re: bfd-like mechanism for LANPHY connections between providers

On Wed, Mar 16, 2011 at 2:33 PM, Jensen Tyler <JTyler at> wrote:
> We have many switches between us and Level3 so we don't get a "interface down" to drop the session in the event of a failure.

This is often my topology as well.  I am satisfied with BGP's
mechanism and default timers, and have been for many years.  The
reason for this is quite simple: failures are relatively rare, my
convergence time to a good state is largely bounded by CPU, and I do
not consider a slightly improved convergence time to be worth an
a-typical configuration.  Case in point, Richard says that none of his
customers have requested such configuration to date; and you indicate
that Level3 will provision BFD only if you use a certain vendor and
this is handled outside of their normal provisioning process.

For an IXP LAN interface and associated BGP neighbors, I see much more
advantage.  I imagine this will become common practice for IXP peering
sessions long before it is typical to use BFD on
customer/transit-provider BGP sessions.

Jeff S Wheeler <jsw at>
Sr Network Operator  /  Innovative Network Concepts

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