...

(TTL should only be decremented when _forwarding_, and I don't think you could argue that you need to _forward_ a packet from your ingress interface to your _loopback_ interface..)

Well, if that were the case, then you wouldn't need multi-hop to do loopback peering.

Different issue (directly connected interfaces vs not directly connected). Easy test: Connect two routers (I used Ciscos) to the same Ethernet switch, sniff the traffic between them. Ping from one router to the other on the directly connected interfaces, observe TTL with sniffer. Ping from loopback on one router to loopback on the other, observe TTL again. I see the *same* TTL in both cases, which means that at least for the IOS version I was testing, TTL is not decremented when sending from the loopback interface. Steinar Haug, Nethelp consulting, sthaug@nethelp.no