[c-nsp] TCN's - Causing brief outages on ASR1K

Lukas Tribus luky-37 at hotmail.com
Mon Dec 15 03:06:26 EST 2014

> Is it expected behaviour for a TCN to cause a flap on an ASR...We have many other POP's with switches
> 4948's/4500's etc(trunk)->ASR+7200's and do not have spanning-tree portfast trunk enabled, and
> they do not experience any flaps?

This has nothing todo with the ASR1k at all. Its expected behavior that STP on the switch will block traffic
when there's a reconvergence, especially when malconfigured (like not using portfast on
router or host connected links).

Why this doesn't happen on your 7k2 we can't tell, there are a lot of moving parts that only you know
(for example whether you are using pvst, rapid-pvst or mst and where exactly the root of those particular
vlans is).




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