lance@hermix.UUCP (Lance Ellinghouse) (11/09/89)
Ok, dumb question time!!
I keep hearing about T1 and T2 service. I know that T1 carries more
(from previous posts). I also know that connecting to the Internet
takes a T1 line (from word of mouth).
Ok, now the questions:
1) What exactly is the difference between a T1 and T2 line?
2) What is the difference in Hardware that is needed to use them?
3) What is the difference in costs? (This is regional and I would like
a general idea if at all possible)
4) How does one hook a computer to a T1 or T2 line? and what
software is needed?
5) Who do you contact for T1 and T2 install/maintance?
6) Can a T2 be used for Internet? or only T1? is there something
cheaper?
7) anything else you can think of....
Direct answer are not needed if you can point me in a direction to
look.
I read Telecom as much as possible and have found it to be full of
answers to other questions that I have had!
Either post or E-mail (and I will summerize if people want).
Thanks!
Lance Ellinghouse
Mark V Systems, Ltd.
UUCP: ...!hermix!lance
ARPA: hermix!lance@anes.ucla.edufleming@apple.com (11/14/89)
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 They were superseded by fiber optic equipment running at multiples of the T3 rate (T3 = 44.736 Mb/s).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. | +-----------------------------------------------------------------------+
carlson@gateway.mitre.org (Bruce Carlson) (11/15/89)
In article <telecom-v09i0499m05@vector.dallas.tx.us> lance@hermix.UUCP (Lance Ellinghouse) writes: >X-TELECOM-Digest: volume 9, issue 499, message 5 of 6 >Ok, dumb question time!! >I keep hearing about T1 and T2 service. I know that T1 carries more >(from previous posts). I also know that connecting to the Internet >takes a T1 line (from word of mouth). >Ok, now the questions: > 1) What exactly is the difference between a T1 and T2 line? T1 is a 1.544 Mbps line, which is often channelized into 24 64kbps channels, may be used at its full capacity, or may be split into odd increments. T1 provides a capacity and a few other technical characteristics, but how you use it is up to you. T2 is a 6.312 Mbps line, which can also be used in various channel setups, depending on the multiplexers and other equipment attached. > 2) What is the difference in Hardware that is needed to use them? The hardware will vary based on how you want to use the lines. Most people want to break the capacity up into channels and/or interface the T1 service to their computers and the exact equipment needed will vary. > 3) What is the difference in costs? (This is regional and I would like > a general idea if at all possible) I don't know the tariffs and I don't > have any estimates. A T1 line is roughly equal to the cost of 3 to 4 56kbps lines when comparing costs, but I don't have any dollar figures. > 4) How does one hook a computer to a T1 or T2 line? and what > software is needed? > 5) Who do you contact for T1 and T2 install/maintance? Local telephone company for local lines, long distance carriers for long distance trunks. > 6) Can a T2 be used for Internet? or only T1? is there something > cheaper? I think you are making a wrong assumption that you need either T1 or T2 to connect to the Internet. Most Internet host connections are in the 19.2 to 56kbps range and most trunk lines (between packet switches) are 56kbps. T1 is being used in some subnets, but it is not required unless you are running applications that need T1 capacity or want to test/experiment with high bandwidth communications. > 7) anything else you can think of.... Disclaimer: Everything I said above is rather general and I don't expect it to be taken as gospel. Trying to explain the Internet and how to connect to it in a few sentences is not that easy. I will try to find you a reference that will give you more complete information. Bruce Carlson MITRE Corp Mclean, VA
MAP@lcs.mit.edu (Michael A. Patton) (11/18/89)
Just a bit of additional info on the subject of "T1 required for connection to Internet". In actual fact, "The Internet" is not a monolithic entity. It is a large collection of networks all speaking the same protocols and with agreements to pass each others packets. This means connecting to "The Internet" is a matter of connecting to one of these networks. In my area (New England), this would most likely be done through NEARnet (the New England Academic and Research network, almost called New England Research and Development network, the acronym is left as an excercise for the reader :-). The current NEARnet fee schedule provides for connection speeds of 9.6k bps, 56k bps, 500k bps, T1 (1.5M bps), and 10M bps. We expect to try out T3 (45M bps) as soon as someone wants it bad enough. In New England it is certainly not the case that you need T1 to connect to the Internet. In all cases the "service" that NEARnet provides is a connector (on the back of a NEARnet-owned router) into which you plug a cable from a drop off your local Ethernet (or whatever, various are supported). The actual details of dealing with the T1 line, or whatever, is handled by NEARnet. __ /| /| /| \ Michael A. Patton, Network Manager / | / | /_|__/ MIT Laboratory for Computer Science / |/ |/ |atton [NEARnet technical group] Disclaimer: The opinions expressed above are a figment of the phosphor on your screen and do not represent the views of MIT, LCS, or MAP. :-)