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(ASCEND) A Cautionary Tale (T-1s and Telcos)
An easy assignment for a new tech. I sent him out to install
some Pipeline 130s on fractional T-1 lines. I handed him
a floppy with the config files he would need, and gave him
diagrams from my notebooks covering everything (what plugs
where, RJ-48 and ethernet cable pinouts, upload instructions,
a screen dump of a "happy" P130 etc. etc.)
He got stalled on the first one. The Pipeline was to be
installed "down the hall" from the telephone room. Symptoms
were as follows:
1) Plug (pre-programmed) Pipeline into RJ-48 cable to
telco's Adtran "FNID", which telco had loopback
tested only hours before.
2) Pipeline reports "CARRIER" on status screen, but
after a few minutes, goes to "Blue Alarm" (All
Ones, meaning a bad upstream repeater or a problem
upstream of an upstream repeater). Ask tech to go
look at lights on Adtran. By then, all lights
except the "power" light are dark. (Strange,
a Blue Alarm from a dead Adtran? Hard to imagine.
Maybe the Pipeline is confused by this state of
affairs, and will not go to Red Alarm for some reason...)
3) Call telco. Yes, there IS a repeater in the circuit,
since the customer premise is so far from the CO.
Telco rolls truck to check repeater, tech goes to
get coffee and wait for a pager message.
4) Telco calls. Nothing wrong with repeater, AND Adtran
STILL loops back just fine, thank you very much.
5) A puzzlement. Page my tech, send him a message to go
look at Adtran lights, call back with results.
6) Tech calls back. Only the Power light is lit on the
Adtran. A further puzzlement. (Adtrans AND PairGains
BOTH show 4 (count 'em, four) green solid lights when
they are happy).
7) Pull out Adtran manual, look at descriptions of lights.
We should have at least the "SX" light on, since a lack
of an SX light means that there is no "Sealing Current"
to the telco side of the Adtran.
8) Call back telco test position. Compare circuit ids,
customer premise addresses, etc. (Multiple new frame
relay drops ordered together, maybe they are testing
the wrong circuit.) No such luck. They loop the
Adtran again, claim all is well, and ask me if my tech
might be drinking something other than coffee this AM.
9) Page tech again, send him message to ask him to check
Adtran lights AGAIN, insure that there is only one
Adtran at that customer site, and insure that he is
looking at an Adtran and not a PBX component or
something. Tech reports that only power light is lit
on ONLY box stenciled "Adtran".
10) Tell my tech to unplug Adtran power supply from wall
socket and cycle power on the unit. (Maybe the customer
prem side is "confused", and need a slap in the face.)
11) Tech calls back. "What power supply?", he asks. (Tech
had never seen an Adtran before.)
12) Call Telco. Ask them when Adtran units started being made
without 120Vac power supplies. Telco rolls truck to deliver
missing power supply to customer site.
13) Expected on-site tech time 20 mins. Actual onsite tech
time 1.5 hours.
Conclusions:
The voltage from the line itself IS enough to light
the "power" light on Adtran units, and enough to make
the Adtran "work" from the point of view of the
telco?
The voltage is also just enough to charge up a few
capacitors in the onboard DC power supply circuits,
and make the Adtran "run" for a little while?
Pipelines get something that they want to call
"all ones" from an Adtran (List 1-5, Issue 2
at least) that has no power on the customer
premise circuitry?
Plugging in Pipeline draws current, and discharges
aforementioned capacitors in Adtran?
Train your techs to look for the pretty green lights
(four, count 'em four!) FIRST !!
How do Bevis & Butthead watch MTV with only a "rabbit-ears" antenna?
james fischer jfischer@supercollider.com
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