> and RFC791 claims ttl is in seconds, ergo I don't have to decrement > ttl because I know my traffic is on paths less than a second > long. > > Cool reasoning. You lose -- 791 says you have to subtract at least 1 from TTL even if. However, I think that (A) most or all extant IPv4 routers violate 791 if they happen hold a packet more than a second, and (B) IPv6 invalidated TCP's correctness by defining the Hop Limit field to be a hop limit and have no connection to time. A TCP riding on IPv6 may receive old segments an unbounded time later without any other network element breaking a spec. I said so at the time, but nobody cared. No doubt Vint will take care of multi-second hops for us.