[ih] X.25

[John Demco]

I was at UBC back then, and among other things I managed CDNnet. Its 
email service was used for a number of purposes we didn’t initially 
foresee. For example, in addition to the UUCP-related traffic Lyndon 
mentions, it was used by clients of the Canadian Microelectronics 
Corporation to assist in chip design, checking, and fabrication.

UBC was also a member of CSnet—an international affiliate, if I remember 
correctly—and a growing volume of email traffic was gatewayed between 
CDNnet and the wider Internet via CSnet. UBC’s Ean X.400 software (due 
mainly to Gerald Neufeld, Rick Sample, and Brent Hilpert) found use in a 
number of European networks and elsewhere, and by 1986 there was an 
increasing amount of email flowing between these networks and the 
Internet, via CDNnet and CSnet.

(By the way, as Lyndon also mentions, Ean’s default configuration was to 
present X.400 addresses in user at host.domain style, but it could also 
represent X.400 addresses more directly, e.g. 
S=Demco;OU=CS;O=UBC;P=cdn;A=telecom.canada;C=ca.)

The growth of costs (especially due to international X.25 charges) was a 
major motivation in establishing a leased line link between CDNnet/BCNET 
in Vancouver and NorthWestNet in Seattle. This was suggested to me by 
Larry Landweber at the 1986 academic network workshop in Dublin hosted 
by Dennis Jennings, and enabled by several others including Hellmut 
Golde and Dan Jordt at UW, Steve Wolff at NSF, and Jack Leigh at UBC. 
The link became operational in 1988, and grew into one of the three 
north-south links between the CA*net and NSFnet backbones in 1990.



John Demco

On 2025-10-01 14:55, Lyndon Nerenberg (VE7TFX/VE6BBM) via 
Internet-history wrote:
> 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.