[comp.protocols.tcp-ip] QUERY: TTL field in IP header

brescia@BBN.COM (Mike Brescia) (02/14/89)

     Why do the "Mail bridges" not decrement the TTL?  Or, do they?

     (on 26.0.0.90)
     #./traceroute ucbarpa.berkeley.edu
     traceroute to ucbarpa.berkeley.edu (10.0.0.78), 30 hops max, 40 byte packets
      1  UCBARPA.Berkeley.EDU (10.0.0.78)  633 ms  769 ms  595 ms
     #

Phil,

I am not sure whether you are claiming to find the "failure to decrement" bug
or the "failure to discard when TTL is 1" bug.  We see the gateways
decrementing the TTL field in packets which they pass.  They should also be
careful to pass a packet only if the TTL is still non-zero when they send it
on, but this may not have been rigorously tested.  Think of it as a fencepost
problem.

Mike