Talk:X.25

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Shouldn't this line:

"Speeds increased during the years, typically up to 48 or 96 kbit/s" read 4.8 or 9.6Kbps instead of 48 and 96?

I think the history of X.25 is too oriented on UK history. France for example made a lot of work to establish X.25 as a standard. TRANSPAC was also the first X.25 packet-switched commercial network in the world.134.214.165.97 18:14, 24 January 2006 (UTC)

Shouldn't "data terminating equipment" be "data terminal equipment"?

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JTE, UK

Correct - in CCITT (now ITU-T) literature DTE is Data Terminal Equipment (and DCE is always Data Circuit Terminating Equipment, not the more colloguial Data Communications Equipment).

"X.25 is an ITU-T standard protocol suite for wide area networks using the phone or ISDN system as the networking hardware".

I disagree fundamentally with that opening statement. X.25 is the __recommendation__ (ie definition) for an __interface__ between a DTE and DCE "for terminals operating in the packet mode and connected to public data networks by dedicated circuit". Specifically it was not / is not a protocol suite for "wide area networks". Such networks were frequently constructed using X.25 with proprietary extensions to cover the missing parts of the protocol. Such networks were complex to maintain and manage because routing, recovery from route failure and private numbering schemes were specifically not covered by the X.25 recommendations ITU-T did not concern itself with the details of network internals. It specifies interfaces into and between network providers including exchange of (some) management, operation and charging/billing details. ITU-T work was delibterately called Recommendations not Standards because they were often a minimum set of rules to obtain a degree of international operation.

Speeds: For the UK, in the early 80's access to X.25 was provided using a V-series private-wire modem link at speeds of 2400, 4800 and 9600bps. High speed "group band" modems provided 48kbps access (at great expense, in a 48kHz analogue channel). When BT first introduced Public Packet Switching, the core of the network ran at 48kbps using V.35 modems. Public PADs provided dial-in async terminal access at 200 or 300bps full duplex (V.21) and 75/1200 (V.23) assymetric full duplex. I believe Germany and France had digital access services using X.21 circuit switching.

[edit] In popular culture

In the movie Father of the Bride, the groom's character is a consultant who helps European banks link their x.25 networks with US-based banks' IP networks. Does this merit inclusion in the article? Jaysbro 20:26, 21 September 2006 (UTC)

Probably not, unless that fact is significant other than something mentioned in passing; I suspect most viewers of the movie would have little idea what an X.25 network is, and would only know what an IP network is because they might have seen references to "TCP/IP" in articles or in the parts of the UI of their computer that they don't like to use. :-) Guy Harris 00:18, 14 November 2006 (UTC)

[edit] X.25 protocols vs. OSI protocols

How many of the protocols listed there were expected to run primarily or solely over X.25? Most stuff above the transport layer was presumably supposed to run over the OSI transport layer protocols, not over X.25; were the transport protocols expected to run directly above X.25, or above OSI network-layer protocols? Guy Harris 00:21, 14 November 2006 (UTC)

---yaaaaa...gr8 work