[c-nsp] wisdom of switchport block ...

[Tarko Tikan]

hey,

> Let's not forget STP topology change notifications (TCNs) because they'll
> cause the MAC address entries to age out in forward-delay (15 sec) or even
> immediately with Rapid-STP.

TCN will also screw up IGMP snooping and will cause multicast flooding 
for N * general-query-timeout. As a best practice, run all customer 
facing ports with portfast and BPDU guard.

-- 
tarko