L2 MTU issues - is BFD proper solution?

Bartosz Radwan b.radwan at citypartner.pl
Thu Jul 3 11:43:39 CEST 2014

We experienced recently several times issues caused by eg. EAPS path 
swich in one of our L2 transmission providers (new path MTU was not big 
enough due to jumbo frames not enabled - that's what they told us, but 
in fact it does not meter - it's out of our control).

 From our point of view this situation sucks - we have several BGP 
sessions, terminated on 2 different BGP routers in different data 
centers, but problems as descripbed above in just one L2 provider 
network may cause our all services are not fully operational - 
especially when afeccted BGP sessions provides best routes for some 
popular services like FB, YT or… redtube.com ;).

So, the question: is BFD able to detect broken L2 MTU and if detected - 
disable affected BGP sessions?

If not BFD, any other ideas?

It's possible to detect L2 problems outside bird and then disable 
protocols, but this may be complicated and error prone, so in fact - i 
do not want to to that.

A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
Bartosz Radwan

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