bfd-like mechanism for LANPHY connections between providers

Tassos Chatzithomaoglou achatz at
Wed Mar 16 13:25:58 CDT 2011

Richard A Steenbergen wrote on 16/03/2011 19:03:
> On Wed, Mar 16, 2011 at 06:56:28PM +0200, Tassos Chatzithomaoglou wrote:
>> Are there any transit providers out there that accept using the BFD (or
>> any other similar) mechanism for eBGP peerings?
>> If no, how do you solve the issue with the physical interface state when
>> LANPHY connections are used?
>> Anyone messing with the BGP timers? If yes, what about multiple LAN
>> connections with a single BGP peering?
> Well first off LAN PHY has a perfectly useful link state. That's pretty
> much the ONLY thing it has in the way of native OAM, but it does have
> that, and that's normally good enough to bring down your EBGP session
> quickly. Personally I find the risk of false positives when speaking to
> other people's random bad BGP implementations to be too great if you go
> much below 30 sec hold timers (and sadly, even 30 secs is too low for
> some people). We (nLayer) are still waiting for our first customer to
> request BFD, we'd be happy to offer it (with reasonable timer values of
> course). :)

Link state is good for the local connection. If there are multiple 
intermediate optical points (not managed by either party), or a lan 
switch (IX environment), you won't get any link notification for 
everything not connected locally to your interface, unless there is a 
mechanism to signal that to you.


More information about the NANOG mailing list