Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucsd!rutgers!texbell!attctc!vector!telecom-gateway From: portal!cup.portal.com!fleming@apple.com Newsgroups: comp.dcom.telecom Subject: Re: T1 vs T2; and Info Message-ID: Date: 14 Nov 89 12:59:37 GMT Sender: news@vector.Dallas.TX.US Lines: 50 Approved: telecom-request@vector.dallas.tx.us X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@vector.dallas.tx.us X-TELECOM-Digest: volume 9, issue 511, message 1 of 9 In response to T1 vs T2; and Info / lance@hermix.UUCP (Lance Ellinghouse): A T1 circuit carries 24 voice channel equivalents at a bit rate of 1.544 Mb/s. There are literally millions of T1 circuits in the North American network today. A T2 circuit carries 96 voice channel equivalents at a bit rate of 6.312 Mb/s. There are literally dozens of T2 circuits in the North American network today. Maybe a slight exaggeration... but T2 circuits are relatively rare. They were superseded by fiber optic equipment running at multiples of the T3 rate (T3 = 44.736 Mb/s). Both T1 and T2 are carried over copper wire... T1 over twisted pair, T2 over a specially shielded (screened) cable. T1 CSUs (the customer interface you need to hook up to a commercial T1 circuit) are readily available from any number of vendors, such as Verilink, Larse, Tellabs, and so forth. I don't know of any T2 CSU vendors, but there might be one out there. The only commercial T2 offering I am familiar with is Staten Island Teleport in New York City. To hook into a T1 line, you need a fast serial port on your computer, usually RS449 or V.35. Then you need a CSU (above). Then you need a deal with a friendly neighborhood carrier (telco, bypass outfit, MCI, electric company, university, or what-have-you) to terminate four wires on your CSU... these will transport the T1 signal. You will need a mirror image at the other end: +-----+ +-----+ +-----+ +-----+ | CPU |----| CSU |--------- ... -----------| CSU |----| CPU | +-----+ +-----+ +-----+ +-----+ data leased T1 circuit data I have no idea if Internet supports T2 access, but I suspect not. For most uses, T1 is a *lot* of data (equivalent of over 100 Trailblazer modems going full blast). Some users, of course, need 45 Mb/s and 150 Mb/s circuits for remote CAD, supercomputer links, broadcast quality video, and so forth, but these users have skipped over T2 and are looking at T3 and SONET. Hope you find this useful. +-----------------------------------------------------------------------+ | Stephen Fleming | Internet: fleming@cup.portal.com | | Director, Technology Marketing | Voice: (703) 847-7058 | | Northern Telecom +-------------------------------------| | Federal Networks Division | Opinions expressed do not | | Vienna, Virginia 22182 | represent Northern Telecom. | +-----------------------------------------------------------------------+