[ih] How long did it take?

[Dave Crocker]

On 9/17/2026 9:02 AM, Michael Grant via Internet-history wrote:
> ... was told that I needed to get X.400 working ... In the lab we had 
> two X.25 networks.  Telenet and one other

An X.400 address was a set of attribute/value pairs, where one of the 
required attributes was the public platform provider.

If your enterprise email was connected to more than one public provider, 
you had two different addresses.

I remember seeing one guy with a business card that showed three or four 
of these on the back of the car, all for the same recipient mailbox.


> I failed to see how X.25 could be used as an internet. 

IP/X.25, using X.25 as a link layer.  For CSNet, Purdue wrote a Unix 
driver to do that.

For the original CSNet email service, everything was dial-up, but that 
quickly included dial-up to a commercial x.28/x.29 commercial service.  
This meant that MMDF's packetized phonenet link layer ran on top of the 
commercial X.25 packet service.

That is, one packet layer over another.  Purdue's driver similarly was 
packet over packet.  We each, separately discovered how important it was 
to make sure the top layer packet was no larger than the bottom layer 
one, if possible.  Otherwise, it doubled the commercial service's packet 
count, and charging was by the packet...

d/

-- 
Dave Crocker

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