[e2e] It's all my fault

George Michaelson ggm at apnic.net
Mon May 14 18:45:52 PDT 2007

Did phone systems have toll-select and explicit long-haul select before
IP networks? manually, I would argue yes. morally, I think asking the
operator to connect your call via a specific path is loose-source..

(for quite a while, it paid to know the fax-attuned IDD prefix to hop
off australia. the QDU's on the line were lower, and it took less
traffic. It seemed to be easier to get round the IDD jogjam at
christmas if you knew the prefix)

back in the JANET coloured book day.. applications like mail had to
have loose-source equivalent because they were lower-stack agile. the
transforms on mail represented paths into the transports along the way
were (to say the least) amusing, and the potential for mish-mash (ARPA
to uk/janet to ARPA to uucp to DECNET to ..) fantastic. Yes, Peter
Honeyman made life easier, in the sense that an offline pre-compute of
the flatness to user at host worked. Sometimes I wish BGP was offline, and
we had defined statics in the DFZ. -Geographics could work in that
model, but I don't think you much want that raised here..

SERC mail was pretty flat, but I believe you could specific explicit
paths. I don't think they mapped cleanly to X.25 hops, but my memory
fades. (mostly, I (and I think everyone else) used X.25 PAD to hop onto
the end system, and logged in to mail local users. I certainly did this
to EMAS at Edinburgh from YKXA on SERCnet. But I do recall an explicit
path notation in a Dec-10 inter-site mailsystem, and in the Jacob Palme
news system which pre-dated UUCP/USENET as far as I know, on Tops-10)
And I think several people independently (re)implemented mail level
explicit path hacks into local mail transports. over and over again.

These kinds of things meant that the clue-density for the userbase was
higher, with respect to what the likely behaviours were for having
explicit control of the lower level packet routing: mentally, you
already had to know this kind of connectivity anyway.

I only used the telnet @path options once myself. But I know of
somebody who used it to force a path into a recalcitrant network when
his interior route died on him. This was in the mod 1990s so its within
living memory that people understood and expected to use this kind of
thing, in extremis.

I was very dissapointed when I discovered how small ATM network
addressing was. Amazing to see a 19th Century circuit switched model
with tiny numberspace for endpoint addressing, and lowly engineers in
boilersuits polishing the shiny brass knobs on crossbar switching
between elements in the path. You really DO know that its a specific
lightpath sometimes.

Should a network prevent people from directing packet-paths? Why?
Should users expect to be able to direct packet paths? Why? 

cui bono?

Beerworthy. But pragmatically, we've taken ourselves to a world where
the dialogue, and the outcome are divorced from this discussion.


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