At 23:27 -0800 2/14/09, Ken Daggett wrote: >On 14 Feb 2009, at 17:43:56 PST, Jonas Lopez wrote: > >> DSL modem on POTS vs. Cable >> >> I did not have a Linksys 4 way splitter, but I did have two DSL >> Modems-telcos, so I discovered you can just attach the phone cord >> to ONLY ONE TELCO MODEM AT A TIME and it will work just fine. >> >> You must disconnect the phone cord in this room to use the other >> modem in the other room - you can not have two phone MODEM >> connections at the same time on the same line. >> >> QUESTION: Since cable does not know who you are - no phone number >> etc.- can you have two cable modems connected at the same time on >> the same cable providing Cable DSL to two machines at the same time? >> >> Yes, I know, getting a 4 port LinkSys would make it work, but I do >> have 2 cable modems on hand. >------------ >Afraid I don't know what "POTS" means, but... > >As each modem is seen as a separate connection to the central switch >pipe to the Internet, is makes sense that the ISP is only going to >let you have the one connection you pay for. > >I expect the engineers at the cable provider are at least as smart. >At the very least I expect you would violate your "terms of service" >and be at risk of some sort of $$ penalty.
There is a lot of confusion here. POTS is plain old telephone service. DSL is digital subscriber link which is a TELCO, telephone company, thing. Until we get fiber to the home DSL works on a twisted pair of copper wires that go from your house to a "switch" which used to be a whole building but can now be a metal box a few hundred meters up the street. Frequency division multiplexing is used on the POTS pair with the band from 300 to 3000 Hz dedicated to old audio telephones. One pair supports one telephone number which can have a bunch of extensions but only one conversation is allowed at a time. Frequencies above 3000, 3 kHz, to about 6 MHz are allocated to DSL. Modems at each end of the pair usually use ATM, asynchronous transfer mode, to talk to each other. The entire frequency band is used up by the modems and is not available for simultaneous use by another pair of modems. At the switch multiple users are connected using some other technique, SONET for synchronous optical network is one, which allow sharing but users have no control over that. POTS instruments need to be protected from the high frequency noise generated by DSL. Some filtering technique is required either at each instrument or at the entrance of TELCO wiring to the house where the external pair is connected to a special pair for the modem and, through a filter, to another pair for the rest of the house. On twisted pair connections the TELCO does know who you are. You're the guy at the other end of the pair and anyone else listening in is guilty of wire tapping and can cause your DSL to fail. A second DSL modem is equivalent to such a tap. It's like two people simultaneously shouting to be heard. Telephone cable is nothing like television cable. A TELCO cable hanging on poles or underground has as many as 600 pairs of twisted copper wire. Television CABLE typically has one central conductor surrounded by cylindrical insulation and a metal shield. Coaxial, COAX, RG-11, RG-6 are common names. COAX uses whatever the cable company wants, usually frequency division multiplexing into "channels" that are roughly equivalent to the channels used for over-the-air broadcasting. The business is changing though and digital tricks are being used to create the uplink which was not envisioned when distribution of television by cable began. CABLE connections need to be told who you are so the modem in your house has to identify itself to the cable company and your signals are mixed with a bunch of others on the street until the cable meets another kind of switch that converts to optical fiber or perhaps a microwave link to the cable company. in short, "Cable DSL", in the original poster's question is an oxymoron. The answers depend on whether the poster has TELCO DSL or TV CABLE company service and it just isn't clear yet. CABLE modems and DSL modems are entirely different. -- --> From the U S of A, the only socialist country that refuses to admit it. <-- --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed Low End Mac's G3-5 List, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list?hl=en Low End Mac RSS feed at feed://lowendmac.com/feed.xml -~----------~----~----~----~------~----~------~--~---
