alexb@sharkey.cc.umich.edu (Alex Beylin) (11/09/89)
In article <telecom-v09i0497m06@vector.dallas.tx.us> David G Lewis writes: >(I could get into a discussion of Class 5 Offices and Class 4 Offices >and Heirarchical versus Non-Heirarchical Routing and Access Tandems, >but that would just unduly confuse the issue... :-)) I, for one, would like to see such a discussion. Overall, I have to say that in the last few month comp.dcom.telecom has moved to the top of my .newsrc due to postings by people like David and Larry. Please, if time permits, do go into discussions of how things work. On a side note, did anyone ever assembled a reference list for telephony textbooks, from basic to complex? Alex Beylin, Unix Systems Admin. | +1 313 948-3386 alexb%cfctech.uucp@mailgw.cc.umich.edu | Chrysler Financial Corp. sharkey!cfctech!alexb | MIS, Distributed Systems ATT Mail ID: attmail!abeylin | Southfield, MI 48034
bill@toto.UUCP (Bill Cerny) (11/09/89)
In article <telecom-v09i0497m06@vector.dallas.tx.us>, nvuxr!deej@bellcore. bellcore.com (David Lewis) writes: > Another approach often used, instead of running 7000 wire pairs, is to > locate a Remote Switching Unit, or RSU, on the customer premises. An > RSU is a "module" of a central office switch which has a control link > and a transport link to the main switch. The control link is > essentially an extension of the switch control bus, usually running > over fiber these days; the transport link is a high-capacity fiber > link. AT&T calls their version of this product the Optical Remote Module (ORM), and SW Bell uses ORM's to link Tenneco's various Houston locations into a "city-wide" centrex provided from a 5ESS. > The RSU isn't a switch in that it has no standalone > "intelligence", instead being directly controlled by the central > processor in the main switch Not strictly true anymore. I believe an AT&T Remote Switching Module (RSM) can be configured for stand-alone operations, and Northern Telecom will soon have a stand-alone remote switching unit. This touches on a very hot issue: telco provided CPE (a real no-no). When Tenneco selected SW Bell city-wide centrex, the PBX association filed a lawsuit which categorized the on-premise remote as CPE. SW Bell responded by categorizing it as central office plant. The judge ruled SW Bell may not locate the remote in the customer's portion of the building, i.e., SW Bell must lease space for its remote apparatus, or place the remote in a physically separate facility (e.g., underground vault). In the Tenneco situation, a corner of the basement was walled off, and a telco-keyed lock installed. As if that made a fundamental difference... Bill Cerny bill@toto | attmail: !denwa!bill | fax: 619-298-1656