<p dir="ltr">Telenet used X.75 inside but I'm not sure what Tymnet used or when they used it. If anybody has any recommended bedtime reading for (technical) details of the internals of Telenet and Tymnet, especially TYM2, I'd be quite interested.</p>
<p dir="ltr">Jim Carpenter</p>
<div class="gmail_quot<blockquote class=" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">the US-based Telenet and Tymnet both offered X.25 service and implemented X.75 I believe.</div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Aug 8, 2015 at 11:04 AM, John Day <span dir="ltr"><<a href="mailto:jeanjour@comcast.net" target="_blank">jeanjour@comcast.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">X.75 was widely used within PTT packet-offerings. As you would imagine mostly outside North America.<br>
<div><div><br>
<br>
> On Aug 8, 2015, at 10:18, Miles Fidelman <<a href="mailto:mfidelman@meetinghouse.net" target="_blank">mfidelman@meetinghouse.net</a>> wrote:<br>
><br>
> Which raises an obvious question: Did X.75 ever get much traction? In<br>
> my days at BBN (1985-1992), and for a few years earlier, when I was<br>
> selling time sharing services, and using TELENET, I can't really recall<br>
> ever encountering it in real use.<br>
><br>
> Miles<br>
><br>
> Vint Cerf wrote:<br>
>> Larry Roberts asked me what he should use for protocol in Telenet and<br>
>> I said TCP but he said he could not sell datagrams and went on to<br>
>> develop X.25's virtual circuits with French, Canadian and UK<br>
>> assistance at CCITT (now ITU-T). That was standardized in 1976 while<br>
>> TCP was evolving. I told him we would run TCP (eventually TCP/IP) over<br>
>> X.25 and by 1981 or so that is what we did in CSNET. 1822 was never a<br>
>> contender for a global standard. X.25 begot X.75 which was the CCITT<br>
>> response to the Internet's TCP/IP.<br>
>><br>
>> OSI was yet another effort to craft a non-TCP/IP Internet and that got<br>
>> started in 1978, using X.25 as the underlying virtual circuit basis.<br>
>> Eventually an OSI connectionless mode was developed CLNP but never<br>
>> gained much popularity.<br>
>><br>
>> The TCP/IP vs OSI battle lasted from 1978 to 1993. X.25 was around<br>
>> from 1976 to 2003 or so as I recall. I shut down the last MCI X.25<br>
>> offering about 2003 or so if memory serves.<br>
>><br>
>> On Sat, Aug 8, 2015 at 3:42 AM, Miles Fidelman<br>
>> <<a href="mailto:mfidelman@meetinghouse.net" target="_blank">mfidelman@meetinghouse.net</a> <mailto:<a href="mailto:mfidelman@meetinghouse.net" target="_blank">mfidelman@meetinghouse.net</a>>> wrote:<br>
>><br>
>><br>
>>> On 08/08/2015 08:12, Jack Haverty wrote:<br>
>>> ...<br>
>>>> But I don't think there's much written<br>
>>>> material about that battle between TCP/IP and X.25 in the<br>
>> ARPANET arena.<br>
>><br>
>> Jack,<br>
>><br>
>> Granted that the TCP/IP cutover happened 2 years before I got to<br>
>> BBN, so my exposure wasn't quite firsthand -<br>
>> but weren't the battles really between 1822 and X.25, and then<br>
>> TCP/IP vs. the ISO stack? After all, 1822 and X.25 were both<br>
>> single subnet protocols, with no support for internetworking (and<br>
>> that IP runs over both of them, just fine).<br>
>><br>
>> Miles<br>
>><br>
>><br>
>><br>
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