27 Nov
2014
27 Nov
'14
12:49 a.m.
From: Clem Cole
A few comments on aspects I know something of:
BTW: the Arpanet was not much better at the time
The people at BBN might disagree with you... :-)
But seriously, throughout its life, the ARPANET had 'load-dependent routing',
i.e. paths were adjusted not just in response to links going up or down, but
depending on load (so that traffic would avoid loaded links).
The first attempt at this (basically a Destination-Vector algorithm, i.e. like
RIP but with non-static per-hop costs) didn't work too well, for reasons I
won't get into unless anyone cares. The replacement, the first Link-State
routing algorithm, worked much, much, better; but it still had minor issues
damping fixed most of those too).
DH11's which were a full "system unit"
Actually, two; they were double (9-slot, I guess?) backplanes.
The MIT guys did ARP for ChaosNet which quickly
migrated down the street
to BBN for the 4.1 IP stack.
Actually, ARP was jointly designed by David Plummer and I for use on both
TCP/IP and CHAOS (which is why it has that whole multi-protocol thing going);
we added the multi-hardware thing because, well, we'd gone half-way to making
it totally general by adding multi-protocol support, so why stop there?
As soon as it was done it was used on a variety of IP-speaking MIT machines
that were connected to a 10MBit Ethernet; I don't recall them all, but one
kind was the MIT C Gateway multi-protocol routers.
Hey it worked just fine at the time.
For some definition of 'work'! (Memories of wrapping protocol A inside
protocol B, because some intervening router/link didn't support protocol A,
only B...)
Noel