Time to live values for IP networks.

[Ron Natalie]

Every module that processes a packet should decrement time to live by
the number of seconds that it has the packet (minimum of 1 if less than
one second).  What a counts as a module is unclear.  In the gateways
we use, I decrement it once on the way in, and if the packet is not
for the gateway itself, once on the way out.


You just pick a time to live value that you think is reasonable to get
it to the destination.  Note that the old 4.1 TCP code used to decrement
ttl by 5 on input and output.  This seemed a little excessive.

-Ron