[ih] X.25

[Lyndon Nerenberg (VE7TFX/VE6BBM)]

Dave Crocker writes:
> On 10/1/2025 2:15 PM, Lyndon Nerenberg (VE7TFX/VE6BBM) via 
> Internet-history wrote:
> > I think X.25 got more of a workout as a transport layer for UUCP
> > (f protocol).  UUCP over X.25 hauled a lot of email and Usenet
> > traffic in the 1980s.
>
>
> I don't recall any of the details about this for UUCP.  For CSNet, we 
> used X.28/X.29, treading the path as a simple dial-up channel.
>
> Was there a protocol layer between UUCP and X.25.  The OSI model called 
> it a 'convergence' layer.

Well, yes.  The X.28/X.29 PAD interface was implied.

But UBC did a native X.25 implementation for 42BSD.  In fact, they
did a pretty substantial ISO stack.  This ran at a number of Canadian
universities, and was the foundation for CDNnet -- a Canadian X.400
email network that ran in the 1980s.  The X.400 addresses mapped
to 822-style addresses as user at host.cdn.  Several UUCP sites in
Canada could gateway to the X.400 network using the
.cdn pseudo-domain.  They probably didn't advertise that in the UUCP
maps.

Hopefully someone from UBC is lurking and can provide more details.
I wan't involved in any of this, and my memory is a wee bit fuzzy.

--lyndon

P.S.  When country TLDs became A Thing, there was some debate in
Canada whether we should adopt .cdn as our TLD, since it was already
in use for the X.400 network.  Thankfully, sanity prevailed.