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From: macy@fmsystm.uucp (Macy Hallock)
Newsgroups: comp.dcom.telecom
Subject: Re: AT&T Service Interruption
Message-ID: <72227@bu.edu.bu.edu>
Date: 13 Jan 91 16:26:00 GMT
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X-Telecom-Digest: Volume 11, Issue 35, Message 2 of 6


In article <16013@accuvax.nwu.edu> JR writes:

>>     In the 1980s, long-distance companies laid thousands of miles of
>> high-capacity optical fiber cables, which carry phone calls or data in
>> enormous volume as rapid pulses of light. But some research has raised
>> concerns that concentration of calling through single wires brings a
>> higher threat of disruption.

>US WEST Communications (NE) is offering special, "self-healing"
>(whatever THAT means) fiber service to major business.  I have
>forgotten the two options, but one includes installing TWO cables to
>the business, fed from opposite directions.  One is (presumably) idle
>(spare?) while the other one operates.  In the event of an outage, the
>system automatically (again, presumably) switches to the back-up
>cable.

Due to the mindset of many phone companies, this is a poor option.  In
most (but not all) area, what you get is a feed to the same CO for
both cables.  The protection you receive is partial at best.  What I
have seen is:

Two entrance cables, entering at separate points...that meet somewhere
down the street and use the same feed cable back the the same central
office.  This yields no protection against many, if not most, types of
failures.  Examples: truck hits phone poles, takes out major cable or
backhoe digs up backbone cables

In Chicago and a couple other cities, their are companies that offer
intra-city local feed cable (usually fiber) that can be used to access
your IXC independantly of the telco's cables and CO.

We advise our customers with critical communications needs to have two
separate feeds to two separate IXC's using a different link to each.
Around here, the only real alternative to using the local telco for
network access is a microwave link.  And that's what we suggest.

Many customers do not want to pay the costs associated with this kind
of redundant service.  And in every instance, they have been out of
communications at some time for a period.  The reasons are many: cut
cable, CO outage, IXC failure ... the effect is the same.

Another curiousity: In Ohio, the telco's have written into their
tariffs that each premises shall have only one entrance point.  Ask
for redundant feed cables, and the first thing they do it cite the
tariff.  I have also seen them violate this tariff provision
repeatedly for their own convenience.  When confronted with this the
answer is almost always "necessary to provide required service" or
some other variation.


Macy M. Hallock, Jr. macy@fmsystm.UUCP 
macy@NCoast.ORG uunet!aablue!fmsystm!macy