[ih] TTL [was Exterior Gateway Protocol]

[Stephen Casner]

On Sat, 5 Sep 2020, Jack Haverty via Internet-history wrote:

> 4/ TTL was also intended for use with different TOS values, by the
> systems sending voice over the Internet (Steve Casner may remember
> more).  The idea was that a packet containing voice data was useless if
> it didn't get to its destination in time, so TTL with a "fastest
> delivery" TOS enabled the sender to say "if you can't deliver this in
> 200 milliseconds, just throw it away and don't waste any more
> bandwidth".   That of course wouldn't work with "time" measured in hops,
> but we hoped to upgrade soon to time-based measurements.

I don't recall any discussion of that idea while we were developing
RTP.  As you say, the units being in hops rather than time would make
this mechanism imprecise, and the variability in the diameter of the
network would make it hard to use.  Multicast complicates that even
further.

                                                        -- Steve