djb@loligo.cc.fsu.edu (Dave Brightbill) (12/11/89)
My rural community is served by Centel. A few years ago, we upgraded our home service from a 4-party line to a private line. Because of a lack of available pairs, we had to wait for a line. The telco solved the problem by installing some sort of magic box on a post in our community. All of our lines have been wired back to it. The installer called it a "slick-96" box, and from her description, I would guess that it is some sort of mux. My guess is that the "96" refers to 9600 baud. So is this a digital mux? Can it do any tricks?
MAP@lcs.mit.edu (Michael A. Patton) (12/12/89)
Date: Sun, 10 Dec 89 20:52:59 EST From: Dave Brightbill <djb@loligo.cc.fsu.edu> [In our rural community] we upgraded ... from a 4-party line to a private line. [There was] a lack of available pairs [which was solved] by installing [something] called a "slick-96". I believe it's a SLC-96 (pronounced "slik-96"). It stands for Subscriber Line Carrier, 96 channels. They use T1 (or similar) connections from the box to the CO, this gives them 96 subscriber drops off the box. It comes in various sizes, I have also seen sizes for one or two T1 circuits and for a T3 circuit. The latter was installed in an industrial park where I was working and (except for a short interruption when the installer accidentally cut the wrong wire :-) we couldn't notice the difference. Running one T3 circuit back to the CO was cheaper (or as cheap) than stringing another N-pair cable, and it freed up pairs for use in neighboring residential areas that were also expanding. These units seem to be much better than the ones they try and use to get two lines out of one. You probably lucked out that they didn't just do one of these funny mux things between you and whoever you formally shared the pair with. Maybe the tariffs don't let them use those when they're two seperate residences.
dave@uunet.uu.net (Dave Levenson) (12/12/89)
In article <2018@accuvax.nwu.edu>, djb@loligo.cc.fsu.edu (Dave Brightbill) writes: > My rural community is served by Centel. A few years ago, we upgraded > our home service from a 4-party line to a private line. Because of a > lack of available pairs, we had to wait for a line. The telco solved > the problem by installing some sort of magic box on a post in our > community. All of our lines have been wired back to it. The > installer called it a "slick-96" box, and from her description, I > would guess that it is some sort of mux. My guess is that the "96" > refers to 9600 baud. So is this a digital mux? Can it do any tricks? We, too, have service from the local telco via SLC-96 (which is Subscriber Loop Carrier, 96 channels per T-1 span). This system uses digital multiplexing and local switching to concentrate a large number of subscribers on a small number of 1.55 Mbit digital loops to the CO. It regenerates battery feed, ringing, loop current interrupts, and anything else needed to support your local Tip and Ring telephone sets. A group of T-1 links to the CO (or fiber, in some installations) provide the physical circuits. Each T-1 link supports 24 derived voice circuits, using digital multiplexing. The actual ratio of supported subscribers to available derived circuits is engineered to provide an acceptable blocking probability, based upon the traffic generated by the subscribers served. When you're using a CO line, you get switched on to one of the available derived channels. When you're not, no channel is assigned. It's fast enough that you'd never notice it, except for the minute probability that no channel will be available when you want service. In that case, you'd experience a wait for dial-tone, or a party calling you would experience a fast busy (I think). We have run voice and data through that mux for several years, and have never experienced data integrity or blocking problems. The transmission quality is noticably better than it was when we had loaded-loop metalic circuits, a few years ago. When it was first installed, the remote terminal was buried in a vault under a man-hole a few blocks from here. There was a lot of excavation, and lots of noise while it was under construction. This moved a few of our neighbors to ask the town zoning board to deny permission to the Telco for use of their easement in this manner. I don't know how the politics finally were resolved, but the mux was cut back in about 1986 or so, and probably bothers nobody today! Dave Levenson Voice: (201) 647 0900 Westmark, Inc. Internet: dave@westmark.uu.net Warren, NJ, USA UUCP: {uunet | rutgers | att}!westmark!dave [The Man in the Mooney] AT&T Mail: !westmark!dave
telecom@eecs.nwu.edu (Various Writers) (12/12/89)
[Moderator's Note: There have been numerous replies to the 'Slick 96' message which appeared a couple days ago. Yesterday I printed three replies, and today, four more are presented in summary form, for the sake of helping to clear the present backlog in the queue. Dave Brightbill presented the original questions/comments. PT] In article <2018@accuvax.nwu.edu> djb@loligo.cc.fsu.edu (Dave Brightbill) writes: >My rural community is served by Centel. A few years ago, we upgraded >our home service from a 4-party line to a private line. Because of a >lack of available pairs, we had to wait for a line. The telco solved >the problem by installing some sort of magic box on a post in our >community. All of our lines have been wired back to it. The >installer called it a "slick-96" box, and from her description, I >would guess that it is some sort of mux. My guess is that the "96" >refers to 9600 baud. So is this a digital mux? Can it do any tricks? ======================= Organization: Leptons and Quarks, Winfield, IL 60190-1412 Date: 11 Dec 89 23:26:10 CST (Mon) From: Randolph J. Herber <root@yclept.chi.il.us> It is a Subscriber Line Interface Circuit (96 lines). Yes, it is a mux. Yes, it is digital. No, it does not do tricks. It is used to concentrate 96 subscriber circuits to a single metallic line or optical fiber which then runs to the telephone exchange. In your case, it is probably using your original metallic line. Randolph J. Herber, @ home: {att|mcdchg|laidbak|clout|obdient|wheaton}!yclept!rjh, rjh@yclept.chi.il.us ========================== From: Paul Guthrie <pdg@chinet.chi.il.us> Reply-To: Paul Guthrie <pdg@chinet.chi.il.us> Organization: The League of Crafty Hackers Date: Tue, 12 Dec 89 08:29:27 GMT The SLC in SLC-96 stands for Subscriber Loop Carrier (althout I have also heard the C stand for Concentrator, but I think Carrier is right). The 96 stands not for "9600 baud", but for the 96 lines that are concentrated onto a T-1 type trunk interface, which normally carries 24 channels. The quick will notice a 4:1 ratio on the SLC-96. I don't recall the signalling protocol. Paul Guthrie chinet!nsacray!paul ============================ From: Paul Elliott x225 <optilink!elliott@ames.arc.nasa.gov> Date: 12 Dec 89 16:02:18 GMT Organization: Optilink Corporation, Petaluma, CA The box referred to is a "SLC-96 (tm)", which stands for "Subscriber Loop Carrier - 96". This is a four-T1 system. A T1 circuit uses two pairs of special wire, running at a digital rate of 1.544 Mbit/sec. Each T1 circuit carries 24 channels of PCM. 24 channels times four circuits equals 96 channels, hence the "96". The SLC-96 has been in service for many years, and has been widely cloned. It is a convenient size for providing service to remote clusters of subscribers. The SLC-96 can provide some types of data service via different line card plug-ins, however I am not familiar with all the offerings, or the cost and availability of them. Can anyone out there comment on this? Regards, Paul M. Elliott Optilink Corporation (707) 795-9444 {pyramid,pixar,tekbspa}!optilink!elliott "I used to think I was indecisive, but now I'm not so sure." ============================ From: Peter Desnoyers <desnoyer@apple.com> Date: 12 Dec 89 17:19:06 GMT Organization: Apple Computer, Inc. 96 refers to 96 phone lines - 4 DS1s (also known as T1s), which is actually a DS2. (I guess DS2s do exist outside of add-drop multiplexors.) The data rate is 96*64000 bps plus DS1 and DS2 framing overhead, or somewhere around 6.2Mbps. I don't know if you can get DDS (56kb/s) or T1 (1.544Mb/s) lines off of a SLIC, though. I have heard (rumor only) that it is possible - if the switch software can handle it - to provide basic rate service on some SLICs by dedicating 3 lines for D, B1, and B2, plus the appropriate hardware. I would appreciate it if someone could tell me whether there is any truth to this. Peter Desnoyers Apple ATG (408) 974-4469 [Moderator's Note: In each response above, extensive quoting was removed in order to save time in re-reading the same quotes, and to allow more space for replies from readers. PT]
fleming@cup.portal.com (12/14/89)
>djb@loligo.cc.fsu.edu (Dave Brightbill) asks: >My rural community is served by Centel. A few years ago, we upgraded >our home service from a 4-party line to a private line. Because of a >lack of available pairs, we had to wait for a line. The telco solved >the problem by installing some sort of magic box on a post in our >community. All of our lines have been wired back to it. The >installer called it a "slick-96" box, and from her description, I >would guess that it is some sort of mux. My guess is that the "96" >refers to 9600 baud. So is this a digital mux? Can it do any tricks? SLC*96 (trademark of AT&T) is a 'Subscriber Loop Carrier - 96 lines'. Also called a pair-gain device, it performs analog to digital conversion on up to 96 telephone lines and transmits them over 8 copper pair (4 digroups) to a central office switch. It is an environmentally hardened channel bank, or time division digital multiplexer with analog interfaces. Nothing to do with 9600 baud... but a reasonable guess! It can do a lot of neat tricks, but none that are accessible to an end-user. SLC*96 is now being replaced with SLC Series 5, which performs essentially the same function but in about half the space, and Northern Telecom's DMS-1 Urban, which provides additional pair-gain savings through a concentration function. +-----------------------------------------------------------------------+ | 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. | +-----------------------------------------------------------------------+
hrs@batavier.att.com (Herman R Silbiger) (12/15/89)
A predecessor to Subscriber Loop Carrier systems was Subscriber Loop Multiplex (SLM). The SLM-40 provided 40 channels, and used Delta Modulation coding. As far as I know, this was the only use of delta modulation in the US telephone network. Herman Silbiger
mlm@homxc.att.com (Mark L Milliman) (12/17/89)
Here is one additional reply to the many others on AT&T's SLC(r) 96 Subscriber Loop Carrier System. SLC is a registered trademark of AT&T Technologies, Inc. As stated by others, the SLC 96 carrier system is a digital subscriber carrier system that provides for up to 96 subscriber channels, when fully equipped, between a central office terminal (COT) and a remote terminal (RT). The subscriber channels are pulse code modulated and then time division multiplexed into DS1 (1.544 Mb/s) type signals. The DS1 signals are then processed for transmission facilities. In addition to single and multiparty message telephone service, the system can provide coin service, voice-frequency special services, digital dataport service, and voice-data circuit switched digital capabilities. The system can operate in three modes: Mode I - Provides 96 dedicated lines over 4 T1 lines. Mode II - Concentrates groups of 48 lines onto 24 channels or 1 T1 line. Mode III - Provides 48 special service, coin, or dataport channels per system. The signals can be transported between the COT and RT electrically or optically at the DS1, DS2, or higher order optical rate. This system was introduced in the early '80's as an economical replacement to the single copper pairs that run from the line card in the exchange to each subscribers home. Since that time a number of other vendors have introduced similar systems to the SLC 96. Because what once took 96 pairs of wires now takes 5 pairs (4 service and 1 protection), this equipment is called a pair-gain system. There is a sucessor to SLC 96 called SLC Series 5. This new system is similar to its predecessor but it serves twice as many subscibers in the same space with less power. It also has many enhanced features over SLC 96. One of those features is the capability to replace those copper pairs that extend from the RT to the home with fiber optic cable. Mark L. Milliman Internet: mlm@homxc.att.com AT&T Bell Laboratories UUCP: att!homxc!mlm Holmdel, NJ 07733 (201)949-0796 I want my ftp!