Saturday, November 17, 2018

Doing BFD on Internet circuits

I’m looking for input from the crowd here. BFD on INET circuits: yay or nay?

I read in some other threads here that most providers will not even offer BFD on an INET circuit. Ours did. 300ms interval with 3x hold timer (so 900ms failover... hey, it’s still sub-second!)

My concern is that both of our circuits running the BFD have both flapped within a one weeks time after standing these connections up. One has flapped once, the other 2-3 times.

Are INET circuits just too noisey to run BFD? My concern is prior to turning on the BFD the one circuit was rock solid pretty much for a whole year.

A stable circuit should have its uptime measured in months, not hours/days. I’m worried that if it flaps too much we’ll get Dampened or something and take a huge outage. Plus we have one app that hates flaps and has to manually be cleared out of a session table. Said app being down is pretty much a hard work stoppage.

It sounds like the decision should be easy: just have them turn BFD off and accept the 90-180 second failover time of typical BGP. Problem is not every member of the team agrees with that outcome.

Any advice?



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