[ih] Source routing, IEN 80, and IEN 95 (in use)

[jfh]

> but my impression is that while people *thought* it would be
> > >> important, in reality no one cared too much and it wasn't used
> much. 

One other comment:

Since Source Routing involved using an IP option field, packets that
were source-routed necessarily got bigger.   Also, there was a tendency
for people to try to put as much data in a packet as possible, since one
of the limitations of the routers (and hosts) at that time was the
number of packets per second that could be processed.

When an already-full packet got bigger because of source-routing, the
packet was much more likely to be fragmented somewhere, which pretty
much everyone agreed was a Very Bad Thing, causing all sorts of problems
and to be avoided at all costs.  It also could seriously change the
behavior of the packet as it went through the system, which would make
any kind of performance measurement data possibly useless.

So, I think people might have cared about getting the desired behavior
from source routing, but the undesirable side-effects may have made them
abandon the use of it.

The best people to ask would be the packet voice crowd from the 80s,
e.g., the SRI and ISI groups.

/Jack