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Joined: Jun 2007
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The trouble is dropped calls and line disconnect messages. XO is swearing up and down that the problem is my system, cabling, CSU, phones, users, building, position of the moon. Reason I ask about the voltage passing out of the smart-jack is because it's just one less thing to test. I've run down everything else I could and am kind of just taking stabs in the dark here. It's kind of ridiculous the length's i'm going to but it's all in the name of good customer service I guess. Basically it's a smaller inbound call center that recieves around 300 calls per day, and they have been getting 3-5 dropped calls per day. The have also had issues with people attempting to call into the 800# from various area codes and getting call disconnect messages. They have re-broadcasted the route as it was found not all the different areas had gotten it the first time but they are still getting reports of this. Their latest stance is that it's my problem so now I am in the position of producing irrefutable evidence that their switch is A) issuing hang-up's to ME and B) that it's not even passing the call to me to decline. I do not know if I am on their Sonus soft-switch or their DMS-500, but I have another customer 30-minutes down the road with the same hardware set-up without issues. If there's any CO switch guys in the 386-676 area send me a PM, I might want to bribe you to take a peek at something smile

Here's what my CSU shows:
***** w1g1: T1 Alarms (Framer) *****

ALOS: OFF | LOS: OFF
RED: OFF | AIS: OFF
YEL: OFF | OOF: OFF

***** w1g1: T1 Alarms (LIU) *****

Short Circuit: OFF
Open Circuit: OFF
Loss of Signal: OFF


***** w1g1: T1 Performance Monitoring Counters *****

Line Code Violation : 3619
Bit Errors (CRC6/Ft/Fs) : 0
Out of Frame Errors : 0

Rx Level : > -2.5db


And my CSU/DSU config is as follows:
CSU/DSU w1g1 Configuration:
Media type T1
Framing ESF
Encoding B8ZS
Line Build 0db
Channel Base 1-24
Clock Mode Normal

Clock mode normal means CPE clock I.E. slave from PSTN. What I'm trying to figure out is where the line code violations are coming from. Do I think this is why someone from New Jersey cant call in? No. But it's the ONLY thing I see giving error's on my side.

Right now I've got PRI debugging enabled and am running a full D-Channel log so that way when the customer drops calls I can just send them the D-Channel log to give to XO so XO can explain why their switch issued a Cause Code 16 to mine (call-clearing/hang-up).

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Looks like you can pull some pretty valuable info out of your CSU card.

How often are you getting the line code violations?

How long did it take to reach the count you're showing?

There could be a mux mis-optioned some place, but I would think you'd also get bit errors.

If there is a mux mis-optioned it should show up when Telco does an all zero's test. Bad repeater should show up on an all one's test.


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Does your system allow you to clear the counters for the bipolar (line coding) violations? If so, reset the counters, and monitor how rapidly they are accumulating. If they are accumulating very rapidly, see if XO will send someone out to check their smartjack (tell them they need to check for a "dirty jack").

I've encountered bipolar errors in the past, similar to what you're experiencing, but the errors were accumulating very rapidly. It turned out to be caused by a faulty connection between a PRI card and it's smartjack/chasis. The card was simply reseated, we cleared the counters again, and no bipolar errors have been recorded eversince. The provider referred to this type of cause as "a dirty jack".

At least see if you can clear the counters to see how rapidly they are accumulating. Since this symptom is intermittent, see if the customer can provide any types of patterns whatsoever which may help out in narrowing this down.

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Good point Mike. BPV's usually indicate a bad termination some place and it they aren't showing up at the Telcom equipment and just yours that will narrow it down.


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Yes, I can clear stats. Those stats are from about 2am this morning. I have been trying to get the XO switch tech to call me so that I can loop the card for the reasons you mentioned bill.

Mike: I'll just try reseating the card shortly before I reset the stat's. If that's the fix then I owe you some beers.

Here's one more debug screen, but it shows no errors.
------------------------------------------------------
w1g1: AFT COMMUNICATION ERROR STATISTICS
------------------------------------------------------

RX Stats:
Number of receiver overrun errors: 0
Number of receiver CRC errors: 0
Number of receiver Abort errors: 0
Number of receiver corruption errors: 0
Number of receiver PCI errors: 0
Number of receiver DMA descriptor errors: 0
TX Stats:
Number of transmitter PCI errors: 0
Number of transmitter PCI latency warnings: 0
Number of transmitter DMA descriptor errors: 0
Number of transmitter DMA descriptor length errors: 0


You can ignore the PCI and DMA lines, as they relate to the card interfacing to the computer.

I believe my problem is the routing at XO's end, not my system, like I said. Problem is I'm just going to have to prove it the hard way I guess.

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Well I did a lil’ lookin’ and I don’t think this will be much help, especially after reading your latest post. I could not find anything that states output towards the customer in the form of voltage…

There are VERY rare examples of units that can put a very small amount of voltage out to power a shelf. That was in the range of 2 v p-p.

Everything for the output of DS1 smart-jacks are really stated in the form of dB (decibels) those can range from -0.0 dB to -15 dB outputs.

I did a couple calculations to come up with:
-0.0 dB = about .77 Vrms
-7.5 dB = about .32 Vrms
-15 dB = about .13 Vrms

A VOM is really not an accurate measurement at all really to determine quality of the signal.


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Bryan
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Thanks for the follow-up. Now I can say I know smile

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WOW…. .This post is flying… I’s a lil’ behind (like always) with that last post.

I’m thinkin’ Mike is on to something there. With that many BPV’s in less than 24 hours something physical is junkin’ your signal.

If that turns out to be the case with the relatively small number of dropped calls I’d call that one “naughty jack” not so much dirty. laugh


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Bryan
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:toast:

Hello Gents.

Quick technicalnote. The Telco must remain compliant with ANSI standard T1.403 that stipulates that the network shall not place any DC voltages on the CPE side of the network interface. T1 NIU's (Smartjack) deployed since the mid 1990's no loger had the capability to support span thru powering. I worked on the Tansmission Engineering Staff at Verizon NY, and as a technical and operational member of the T1 NIU & HDSL RFP cross funtional teams, I added the ANSI requirement to remove span thru powering voltages to cross over the network interface (NI) AKS: Demarc.

Removal of span powering voltage to power customer CSU's was also mandated in the legacy FCC interconnection rules found in FCC part 68. The FCC Part 68 requirement went into effect in December 18th, 1989. ANSI T1.403 included the FCC requirement.

Regarding to the logging of incoming BPV's (CV-L), that is an indication of a physical problem at the CSU end of the DS1 circuit, and limited to the metallic T1 portion of the circuit between a LEC local MUX/ or SDL RT unit, assuming such a design, and the customer NI.

I find it interesting that no CRC-6 errors were reported by the CSU. A mis-optione MUX low speed card AMI, where it should be B8ZS, will not produce BPV's, but should register Excessive Zeros if such a PM register exists.

In all Westell T1 NIU's, and Pairgain 2W HDSL equipment, there is an option I specified to show B8ZS seconds. This is a 15 minute bucket that will indicate the presence of B8ZS from both the CPE & Network directions. It is intended to help diagnose a B8ZS/AMI line code misoption.

If there is access to the NIU or the HDSL Remote unit, a F-M DB9 cable connected to a PC serial port, withthe PC running a VT100 terminal emulation application (Procom/Hyperterm), will provide some additional clues as to where any errors may exist.

Second, insure that with a ISDN-PRI, the local PBX is taking timing from the service provider (XO), and is not in Master/Internal/Free Run clock mode.

Regards,

Field Ops
32 years & out

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Well I made a big enough stink at XO that they had one of their line engineers sit down and look at the last mile. He found some issues with a repeater and they are supposively rolling a truck today (saturday) to replace the repeater at some point.

No, I did not talk to the engineer, they opted to call a customer who probably dilluted the message so much it doesn't resemble what they actually said. The "proof" in the pudding will be if I log a d-channel drop/red-alarm at some point during normal hours tomorrow. I can only assume the repeater is on the TX side as i'm not registering any errors on the RX.

Yes, is is configured for normal (CPE) timing, meaning it receives timing from the line. I plan to take a swing by their place monday, plug into the smartjack, see what I can see, reseat it, test the cable, reterminate the cable, retest the cable, and see if my BPV's go away.

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