[ih] Source routing

[Craig Partridge]

I would have said more 733 and 822 email address formats (e.g.
user%host.csnet at relay.cs.net or @bbn.com:dave at dcrocker.net or
ucbvax!ihnp4!harvard!bbn!craig) than SMTP, but indeed SMTP had to allow
them in the envelope.   One goal of MX RRs was to get rid of much of that
cruft :-)

And IP has source routing -- both strict source routing and loose source
routing options.  Strict source routing was infeasible, I believe, by the
early 1990s because there were too many hops in the typical path to fit
into the available IP option space.

Craig

On Sun, Feb 2, 2025 at 11:37 AM Dave Crocker via Internet-history <
internet-history at elists.isoc.org> wrote:

> My recollection is that mechanisms for source routing were common in the
> early days, but lost favor.
>
> UUCP networking (!) was a version.  SMTP originally supported it.  I
> don't think Arpanet packets did, though I have a vague sense there was
> some selectivity allowed.  And I don't think IP did.
>
> I'm curious about a rough summary of when and how it was used and when
> and why it lost favor.
>
> d/
>
> --
> Dave Crocker
>
> Brandenburg InternetWorking
> bbiw.net
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