[c-nsp] necessity of nowadays

[Lukas Tribus]

>> - a had meltdowns because UDLD was not enabled
>
> Why? Had you disabled autonego or why didn't RFI work?

Just because the link is unidirectional doesn't mean one side
sees the link down.

In my case I saw links on both switches up and operational,
output and input packets on switch A, only output packets
on switch B.

This was a optical link between a 7600 and a 3560. Turned
out to be a hardware failure on the 7600 linecard.

Autonegotiation never dropped the link, so there was no RFI.


UDLD or loop guard would have prevented the loop, neither
was enabled at the time.


Lukas