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NWA experiences phone outage
#286671 08/24/07 05:48 AM
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Phil Offline OP
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Yesterday afternoon, down around Ft. Smith, a back hoe operator cut a fiber optic, and all of Northwest Arkansas at&t customers' phone lines went dead - cell phones, land lines, and leased lines, too. You would think that after all this time that they have been in business, they would build a little redundancy into their networks!!

PS - phone service was restored a few hours after the event, but what did that do for the comapny's credibility?


Phil

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Re: NWA experiences phone outage
#286672 08/24/07 08:26 AM
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We had an incident affecting my local C.O. here a few months ago.

The fiber links between Stalham and its parent at North Walsham about 10 miles distant were completely lost. Stalham is now just a remote concentrator unit, but as our system X RCUs can handle a maximum of 2048 lines each, it has two RCUs for the 3000 or so lines served out of Stalham.

The RCU has limited ability to complete calls within its own line concentrator if it loses communication with the outside world, but an RCU can't communicate directly with another RCU.

In this case, we had two RCUs sitting right next to each other in the Stalham C.O., yet unable to complete calls because inter-concentrator calls have to be passed through the parent at North Walsham. So half the lines in Stalham were unable to call the other half.

In the "old days," even if all outside trunks were lost for some reason, at least all calls within the same office could have been completed.

It does make one wonder about the perceived wisdom in some of the modern arrangements.

Re: NWA experiences phone outage
#286673 08/24/07 08:36 AM
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We had something similar here not too long ago. A Verizon cable splicer inadvertantly cut a fiber optic cable in a manhole in Southeast Washington, DC. This effectively isolated their Groveton (Alexandria), VA 5ESS from the rest of the outside world. This office is not a remote, but a full host office with 12 exchanges! How that happened still has me shaking my head.


Ed Vaughn, MBSWWYPBX
Re: NWA experiences phone outage
#286674 08/24/07 09:41 AM
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We usually had self-healing rings in place for the high capacity routes. This would include all of the voice and data circuits between Central Offices. It would also include all of the umbilicals connecting Host switches to the remotes. Diversity was a major priority and it was something that was reviewed on a regular basis. I can remember a couple of locations that did not have this diversity because there was only a single fiber route feeding the office. These were rural offices and the situation changed when a second route became available.

Strange things do happen. I can remember an occasion where an optical transmitter failed in a NEC mux. In an effort to save some money, all the spares were centrally located. The central location was about 45 minutes away. Usually this wouldn’t have been a problem except when the fiber on the other side of the ring gets cut. Luckily the spare transmitter arrived within a couple of minutes of the failure but for that short period everything on the NEC 560 was down.


Gary
Re: NWA experiences phone outage
#286675 08/24/07 03:56 PM
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Interesting thing about redundancy, how often do the redundant fibers, cables, whatever, leave the building and follow the SAME ROUTE for a couple of hundred feet, SIDE by SIDE? smile John C. (Not Garand)


When I was young, I was Liberal. As I aged and wised up, I became Conservative. Now that I'm old, I have settled on Curmudgeon.
Re: NWA experiences phone outage
#286676 08/26/07 08:07 PM
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There is a lot of discussion of path redundancy on the NANOG (North American Network Operators Group) mailing list.

Common issues seem to be (in no particular order):
1. getting the carrier to disclose routing information.
2. ensuring that the carriers do not groom formerly redundant paths into the same fiber/conduit/mux/trench/tunnel/bridge/etc.
3. auditing paths to ensure carrier compliance with contracts/SLA's.
4. Getting the carrier to disclose routing information without a crippling NDA that prevents contract enforcement or future audits.
5. ensuring that the paths remain as planned during/following M&A's.

Re: NWA experiences phone outage
#286677 08/28/07 07:02 AM
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Reminds me of the issue at Dobbins AFB in Georgia. They hired contractors to replace the aging copper from the base's PBX to the telco C.O. The man was trenching from the roadway to a building on the other side of a four-lane road from the base. In his wonderment, he cut through a 300 pr cable that had been clearly marked for location, interrupting communications to/from the base around 3pm.

Hurriedly, the telco was out to correct the cut, and service was restored by the following morning. Trenching to the offsite building was then scheduled to resume.

In an attempt to proceed with caution, the man had relocated the trench about 75 feet to the left. The only problem was the cable run was perpendicular to the trench. He could have moved over 300 feet and still had to cross the path of this cable. So, at 9am, the same contractor cut the same cabe, just 75 closer to the base.

You got to love a consistent contractor.


it's all tip and ring
Re: NWA experiences phone outage
#286678 08/28/07 07:11 AM
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I remember, a few moons ago, I located a toll cable for a contractor way out in the sticks, used flags and paint so there would be no mistake. A few hours later the alarms went off and I high tailed it back to the construction site, seems they thought where the flags and paint was, was where they could dig. :scratch:


Retired phone dude
Re: NWA experiences phone outage
#286679 08/28/07 07:22 AM
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I went to Nortel school with the communications director for Northwestern University years ago. They had the dreaded failure alarms going off in the CO one day only to out that a new tech was on campus dispatching squirrels off the aerial cables with a 410 shotgun. Early 80s...try to get a shotgun near a school these days.


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