North American Network Operators Group

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Re: MCI WorldCom fiber cut in White Plains, NY

  • From: William Allen Simpson
  • Date: Sat Oct 09 23:51:31 1999

(Chuckle)  When I first started looking into SONet back in'92, and later 
with the Milan (Michigan) cut that took out so many "redundant" paths, 
I learned that the "redundant" "ring" part of SONet was "intended" to be 
preventative against an electronics failure, so that a single transceiver 
failure won't kill the circuit.  This is the same reason that they provision 
"Automatic Protection Switching" (APS).  But the two paths on the ring (and 
the APS circuits) are usually both in the same fiber bundle.

For a educational network I was consulting on, they actually ran the pair of 
bundles between buildings in two liner sleeves within a single duct.  Saved 
on right of way.  So, even when you have a firm contract and circuits 
specified, and it looks like a ring on paper, you have no way of knowning 
that they actually gave you geographically diverse paths, without walking 
the couple of hundred miles and inspecting them yourself.

APS is really a useless feature.  Even when you get the contract to say there 
are diverse paths, they will later groom the circuits to put them in the 
same bundle.  

Paul A Vixie wrote:
> why pay the complexity and cost overhead of SONET if you're not building rings?

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