History of Asynchronous Transfer Mode

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	Revision 45 . . December 5, 2001 9:38 pm by The Anome *[clarified point about VPI/VCIs: they could* be consistent along a VC, but there is no requirement]**
	Revision 44 . . (edit) December 5, 2001 9:36 pm by The Anome [wikification]
	Revision 43 . . December 5, 2001 9:32 pm by The Anome [Added another subheading...]
	Revision 42 . . (edit) December 4, 2001 10:28 pm by The Anome [oh, and one more comment about PT]
	Revision 41 . . December 4, 2001 10:26 pm by The Anome [added extra sub-heading, US govt (and hence public domain) external ref for Q.2931 etc...]
	Revision 40 . . (edit) December 4, 2001 9:02 pm by The Anome
	Revision 39 . . December 4, 2001 9:02 pm by The Anome [mentioned PT, GFC uses, defaults]
	Revision 38 . . December 4, 2001 8:56 pm by The Anome *[Mentioned NNI format as diff from UNI format]**
	Revision 37 . . December 4, 2001 8:42 pm by The Anome [Mentioned ATM AALs.]
	Revision 36 . . December 4, 2001 8:27 pm by The Anome [links for circuit and packet switching]
	Revision 35 . . (edit) December 1, 2001 6:42 am by The Anome [links to SDH, PDH]
	Revision 34 . . (edit) December 1, 2001 6:33 am by The Anome
	Revision 33 . . (edit) December 1, 2001 6:32 am by The Anome
	Revision 32 . . (edit) December 1, 2001 6:31 am by The Anome [polished first sentence.]
	Revision 31 . . December 1, 2001 6:09 am by The Anome [ATM is not one layer, added -> network protocol]
	Revision 30 . . November 30, 2001 9:19 am by The Anome [final for tonight...]
	Revision 29 . . (edit) November 30, 2001 9:08 am by The Anome [mentioned multiplexing justification]
	Revision 28 . . (edit) November 30, 2001 9:00 am by The Anome [tidying... spelling...]
	Revision 27 . . (edit) November 30, 2001 8:57 am by The Anome [tidying...]
	Revision 26 . . (edit) November 30, 2001 8:56 am by The Anome [tidying...]
	Revision 25 . . (edit) November 30, 2001 8:54 am by The Anome [OSI/ISO whoops.]
	Revision 24 . . (edit) November 30, 2001 8:51 am by The Anome [mentioned early on that cells are fixed size]
	Revision 23 . . November 30, 2001 8:50 am by The Anome [removed my own comment about article being a mess ]
	Revision 22 . . (edit) November 30, 2001 8:49 am by The Anome [Mentioned UNI/NNI distinction]
	Revision 21 . . November 30, 2001 8:47 am by The Anome [added ASCII diagram of UNI cell]
	Revision 20 . . (edit) November 30, 2001 8:30 am by The Anome [wikified LAN]
	Revision 19 . . November 30, 2001 8:29 am by The Anome [added more on standards culture]
	Revision 18 . . (edit) November 30, 2001 7:23 am by The Anome [telco link changed to telephone company]
	Revision 17 . . (edit) November 30, 2001 7:21 am by The Anome [copyedit, clarify, fix spelling]
	Revision 16 . . (edit) November 30, 2001 6:55 am by The Anome [Spelled out MPLS]
	Revision 15 . . November 30, 2001 6:55 am by The Anome [Spelled out MPLS]
	Revision 14 . . November 30, 2001 6:54 am by The Anome [Fixed IP link targe]
	Revision 13 . . (edit) November 30, 2001 6:53 am by The Anome [added extra comment re echo cancellers]
	Revision 12 . . November 30, 2001 6:51 am by The Anome [first hack at unmessing while NPOVing... any comments?]
	Revision 11 . . November 10, 2001 7:32 pm by Alex [Added some traffic classes, moved some bits I disagreeded with to /Talk for debate.]

Difference (from prior major revision) (author diff)

Changed: 34c34

ATM is a channel based transport layer. This is encompassed in the concept of Virtual Paths (VP's) and Virtual Circuits (VC's). Every ATM cell has a 8-bit Virtual Path Identifier (VPI) and 16-bit Virtual Circuit Identifer (VCI) pair defined in its header. As these cells traverse an ATM network switching is achieved by changing the VPI/VCI values. Although the VPI/VCI values are not constent from one end of the connection to the other the concept of a circuit is (unlike IP where any given packet could get to its destination by a different route to preceeding and following packets).

ATM is a channel based transport layer. This is encompassed in the concept of Virtual Paths (VP's) and Virtual Circuits (VC's). Every ATM cell has a 8-bit Virtual Path Identifier (VPI) and 16-bit Virtual Circuit Identifer (VCI) pair defined in its header. As these cells traverse an ATM network switching is achieved by changing the VPI/VCI values. Although the VPI/VCI values are not necessarily consistent from one end of the connection to the other the concept of a circuit is (unlike IP where any given packet could get to its destination by a different route to preceeding and following packets).