[ih] Exterior Gateway Protocol

[Noel Chiappa]

    > From: Craig Partridge

    > Could Bob have been thinking about splitting off DoD IP networks to
    > another provider ... and using EGP for that purpose?

I was involved with an early incident that _may_ have been part of the
impetus for EGP; I was out of the loop that started EGP, so I can't say for
sure. Well, let me tell the story, FWIW.

MIT got a router (gateway as we called them then) between its collection of
LAN's (mostly CHAOS speaking at that early stage) and the ARPANET somewhat
early on; later than would have been optimal, but there were no spare IMP
ports at MIT, and we had to wait for the installation of IMP 77 (one of the
first C/30 IMPs, I think) to get connected to the Internet. (Jerry Saltzer
worked out when that was, by looking in hardcopies of CSR progress reports
that he had in his garage; I can look it up if it's important. My very vague
memory is that it was roughly around 1980.)

The first ARPANET gateway at MIT was bodged 'Port Expander' code (I found a
version of it in that CSR dump, if anyone cares; I'm not sure it's the
version that was in service, all that stuff is pretty disorganized). To
exchange packets with the rest of the Internet, we needed to let the BBN
gateways (pretty much all there were at the time) know that MIT-GW was the
route to net 18. We decided to do that by hacking up a small MOS process to
run in the same box, which would send a small, short GGP routing update that
just said 'net 18. this way' every so often.

So I coded it up, installed it in MIT-GW, and apparently as soon as I started
it, the BBN gateways started falling over. IIRC, I got a phone call from
someone at BBN, asking what I was doing that was causing their gateways to
crash. This was news to me, I had no idea I was doing that. Anyway, after some
investigation, we figured out what had happened: BBN had changed the format of
GGP routing update, but hadn't documented the change. So when I dutifully took
the routing update format from the GGP spec online, it was malformed in a way
that killed the BBN code.

I have this memory that when this tale was told to Vint at the next Internet
WG meeting, he took out a little notebook and made some notes, and shortly
thereafter we found out that the Internet router work at BBN had moved
between Div 4 and Div 6 - we were under the impression at the time that that
change was a result of those router issues.

I don't know if the start of EGP was also connected, but those events
certainly showed the downside of having new routers trying to talk GGP to the
BBN routers.

	Noel