Valdis.Kletnieksvt.edu
Date: Sat Dec 01 2007 - 23:24:17 CST

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On Sat, 01 Dec 2007 23:13:31 EST, gmaggro said:
> Ah yes, I remember an old story not too dissimilar... multiple redundant
> lines, all severed at the same time with the same backhoe. Idiots.

To be fair, it's often not "idiots". First, you have to find 2 providers
that can get fiber from point A to point B at all (note that if one or the
other doesn't already have dark fiber laid, they're either digging a ditch
or they're going to lease some fiber from a 3rd party). Then you often need
to do NDA's with both to find out where their fibers are and verify that
they in fact are diverse. And then you need to make sure they *stay* diverse.

The following happens a *LOT*:

1) You get Vendor A to give you 4 pairs of fiber that run south on B Avenue,
east on 3rd street, south on D ave, east on 5th st, and then south on E Av.

Vendor B's runs south on C avenue, east on 6th street, then south on F Av.

Except for a few crossovers, they're diverse.

2) Vendor B has to re-groom because of a construction project at C Av & 5th st.
So they re-route to another conduit (not A's) that runs east on 3rd st to F av.

3) Bozo with a backhoe on a water main break nails both conduits on 3rd
street between C Ave and D Ave.

What are your chances of getting vendor A to re-groom your paths off 3rd St
while B has their path going down that street, and then put them back once
B goes back the other way after the construction at C and 5th is done?

Note that sometimes, there really *isn't* a good way to get diversity - how many
ways are there to get an east-west long-haul fiber across the Mississippi
between St Louis and New Orleans? Your choices are limited - under the bottom
of an interstate highway bridge right next to your competitor's conduit, or
you get to trench all the way across the river, and hope you put it deep enough
so if they ever have to dredge the channel, you won't get hit. Similar
issues apply to Manhattan and a lot of other places.

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