[ih] Source routing

[John Kristoff]

On Sun, 02 Feb 2025 18:37:09 +0000 (UTC)
Dave Crocker via Internet-history <internet-history at elists.isoc.org>
wrote:

> I'm curious about a rough summary of when and how it was used and
> when and why it lost favor.

While not IP source routing, I worked at a corporate environment that
had an extensive source route bridged network (token ring) and I was
always told we had one of the largest source route networks in the
world, and I think by an IBM rep.  I wouldn't be surprised if someone
would dispute that claim now, but looking back it seems like a small
miracle it worked as well as it did now.

The company was Hewitt Associates (now gone).  I worked there from
roughly 1994 to 1998.  The architecture was already designed, but I did
help extend it by connecting multiple remote offices into the larger
WAN. We used old IBM PC 55? as the WAN bridge.  We removed the hard
drives and gave each bridge a slightly customized version of the
bridging software and config on a 3 1/2" floppy (there was a backup
floppy in a binder just in case there was a disk failure).  The network
primarily carried SNA and IPX as I recall.  IP didn't come until much
much later, and I think we may have bridged some of it until the turn
of the century, eventually Bay (or whatever they were called at the
time) began to replace them and do IP routing as that became impossible
to avoid.

Obviously this was much different than source routing in IP, but the
concept was not dissimilar.  But, yes, one gigantic layer 2 network
that spanned the US.  In addition to a multi-campus network at HQ in
Northern Illinois I think we had about 30 offices around the country
connective via some variation of T1 or smaller.  Some international
offices were connected via Frame Relay or X.25 as I recall so the
bridged network ended at country borders.

I probably have some old design documents, network maps, ring numbering
plans, and so on if anyone cares to see them.  We first provided
IP (www browsing really) connectivity through a Lotus Notes gateway that
ran IPX to end clients.  Good experience to have *had* but can't say I
miss it.

John