bicknell at dimension.net
Fri Jul 24 00:19:49 UTC 1998
In article <6p89q9$d33 at gizmo.dimension.net> you write:
>I have noticed that different 'fiber cuts' (or other transmission
>facility problems) seem to get different kinds of reactions. Some
>carriers' fiber cuts seem to pass unnoticed. While other carriers'
>cable cuts make the front pages of newspapers across the country.
A lot of it depends on who is impacted by the cut, and how
the cut impacts traffic. Some observations by me, the non-telcohead
router-geek to just buys circuits and expects them to work:
1) Why do my "SONET protected with redundant rings" based circuits go
down from a fiber cut? I have to assume either I was lied to,
and they are not redundant, or both "redundant rings" ran down
the same path...making me wonder what good they ever were in the
Carriers with diverse physical paths win big here.
2) Why do circuits "bounce" after a cut. I've seen circuits pop up
and down after a cut, which just causes all sorts of problems.
I think this mainly comes from attempts to "re-route" traffic.
Having the circuit bounce up and down is almost always worse
then if it was just down.
3) Does the cut take out a lot of little circuits, or a few big ones?
Taking out 4 OC-12's into a mae often makes things 10,000 times
worse than taking out the 360 DS1's that could be in the same
fiber. (IP like networks often can absorb a T1 here or there in
reroutes, but not an OC-12....excess capacity has it's cost.)
I think more data would be highly useful, but not necessarily
in the sort of way the FCC looks at it. The FCC has issues like
"will 911 work", where the ISP has issues like can I provide service
to my users. In some ISP networks losing a circuit would be
inconvenient, but fully planned for and not impact service.
Also, things like point 1, was there a redundant path so the "cut"
had minimal impact are very important to me, as a purchaser of circuits.
There could be a lot of value in an tracking the performance in
a more abstract way than the FCC does.
Leo Bicknell - bicknell at dimension.net
Network Engineer (CCIE #3440) - Dimension Enterprises
1-703-709-7500, fax, 1-703-709-7699
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