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Re: IntraLATA vs. InterLATA Ckt Reliability
From: "Ron Buchalski" <rbuchals () hotmail com>
Date: Tue, 17 Jun 2003 22:33:36 -0400

You can request circuit diversity, and ask for the circuit layout record (CLR/DLR) to verify that the paths are diverse. Standard practice is to assign circuits onto available facilities, and treat each circuit independently. So, there's no concern about whether the circuits share common facilities, unless the orders are flagged that way.

Unfortunately, future circuit grooming may result in your circuits being put onto a common path somewhere.

You can try to get the telco to guarantee diversity in writing, with financial penalties if they fail to maintain diversity. You'll need to provide backup for lost revenue, to determine how much the financial penalties should be.

By the way, there's no guarantee that intralata circuits will always be diversely routed, either. It's all dependent on the available facilities.

For interlata circuits, even if you were to go with two different IXCs, you'll need to insure that they don't share common facilities, or lease capacity on the same fiber. Years ago, a train wreck in the NY-DC corridor caused multiple carriers to experience fiber outages. Seems that one carrier trenched fiber on the right side of the tracks, and another carrier trenched fiber on the left side of the tracks. The derailment dug up both sides!


From: "William R. Lorenz" <wrl () express org>
To: nanog () merit edu
Subject: IntraLATA vs. InterLATA Ckt Reliability
Date: Mon, 16 Jun 2003 17:11:42 -0400 (EDT)

Can someone with a bit of experience in telco line engineering speak to
IntraLATA vs. InterLATA DS-1 circuit reliability?  More specifically, is
it more likely for multiple DS-1 circuits to be aggregated using a single
piece of multiplexing equipment when heading into another LATA, thus
increasing the chance of combined failure of two diverse circuits at a
single point?  I would love to have two diverse T1 circuits coming into
the offices, but it looks like they'll ultimately traverse the same telco
switches, both at the local and regional interconnection levels (? more
info ?), and it seems as though this presents increased risk.  We have
entrance failities for just one LEC in our office building here, and I
understand that a new telco buildout would require lots of investment.

I've actually talked with LEC engineers about the various switching
stations in the area, and it seems as though everything is aggregated
through a single central office before hitting the other LATAs.  Have
others encountered this same kind of topology in the past?  What are some
of the things that can be done to help ensure circuit diversity?

Lots and lots of questions, I know. ;)  Any insight into standard telco
engineering practices would be great and very much appreciated!  Tnx.

--          _
__ __ ___ _| | William R. Lorenz <wrl () express org>
\ V  V / '_| | http://java.sun.com/; http://www.linux.org/
 \./\./|_| |_| "[...] But it's turtles all the way down."

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