[c-nsp] Turning on no ip unreachables and the effects

[Kevin Barrass]

Hi

I've been following a thread on NANOG about PMTUD black holing and as a
result am reviewing our setup here with regards this.

I've seen in the below link that enabling "no ip unreachables" on a
interface can break PMTUD across your network if the outgoing interface
is then on a link with an MTU too small as the interface with "no ip
unreachables" will not send a packet too big type message.

Does anyone have a link to a definitive list as to the effect of turning
on this command as I thought that turning on this command didn't prevent
the interface sending TTL expired and hence not breaking trace route but
now im unsure.

Any feedback appreciated.

Cheers
Kev