Fiber cut - response in seconds?

Deepak Jain deepak at
Mon Jun 1 23:43:10 UTC 2009

I'm not sure why this sounds so surprising or impressive... given g$vt 

Monitoring software using a pair of fibers in your bundle. OTDR or 
similar digital diagnostics. You detect a loss, you figure out how many 
feet away it is. You look at your map.

A simpler way to do it (if you don't mind burning lots of fiber pairs) 
would be to loop up a pair of fibers (or add a reflectance source every 
1000 ft or so -- spliced into the cable). You can figure out to within a 
thousand feet once you know WHICH set of loops has died.

Given it almost always involved construction crews, you drive until you 
see backhoes for your final approximation.

If I were the gov't I'd have originally opted for #2, and then moved to #1.

"Seconds" is just a function of how far away the responding agency's 
personnel ( monitoring the loop ) were from the cut. Obviously we are 
talking about a few miles tops.

Plenty of people used to have a single pair in each bundle for 
"testing". Its relatively trivial to make that a test pair live. This is 
all predicated on you actually keeping your toplogy up-to-date.

Deepak Jain

Charles Wyble wrote:
> Joel Jaeggli wrote:
>> It's pretty trivial if know where all the construction projects on your
>> path are...
> How so? Setup OTDR traces and watch them?
>> I've seen this happen on a university campus several times. no black
>> helicopters were involved.
> Care to expand on the methodology used? A campus network is a lot 
> different then a major metro area.

More information about the NANOG mailing list