[ih] Exterior Gateway Protocol

[Noel Chiappa]

    > From: Grant Taylor

    > Does anyone know of any surviving implementations of Exterior Gateway
    > Protocol, BGP's predecessor. ... Did any other network operating system
    > vendor or 3rd party vendor have EGP implementations?

Liza Martin did one for the MIT so-called "C Gateway". That was distributed to
a number of people, along with the rest of the CGW code. All that code is all
still around (on the dump of the MIT-CSR machine which was recently
retrieved), and easily available.

I later re-wrote that one somewhat, to improve it, for the Proteon router
products. The one big change I recall which I made was to the code which
generated the lists of routes in the updates. To pack as many entriess as
possible into a single packet (IIRC, EGP routing table updates were only
single packets; no provision for overflow into sets of 2 or more), it used a
somewhat arcane organization, which a naive implementation would be slow to
generate. So I wrote code to walk the routing' table, and generate an
intermediate tree structure which was a good match to the layout in the EGP
updates; the code to generate the output packets could then walk that
swiftly. (Or, at least, that's my best memory; it's been ~40 years since I
last looked at it.)

I think I have all that code on a magtape somewhere, so it's retrievable, but
qith some effort. If you just want to see it, I can scan the listings I have
of it.

The other implementatinos I know of were for the BBN PDP-11 router (in
Macro-11, I would assume), and I assume there was one for the Fuzzball
(ditto).


If anyone's super-interested in EGP, Liza had a mailbox of mail with other
people outside MIT about work on EGP (Dave Mills led an effort to modify EGPa
from the original 'EGP1' to, among other things, hold more routes, which is
where that 'packed' format came from). That is in that dump; if anyone is
interested in it, I can go through it and make sure there's no personal
content, and make it available (afer checking with Liza, if I can work out how
to contact her, do make sure it'e OK to let it out).

	Noel