[c-nsp] Line Code Violations

[Barton F. Bruce]

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> switch and have the other side provide clock
>
> then have both sides set to obtain clock from the line
>
> See what happens
>
> Telcos these days all multiplex their circuits together - I am not sure
> exactly
> how they accomplish this without supplying clock to both sides.  Many of
> our point-to-points apparently go through telco equipment that also isn't
> sure exactly how to accomplish this either, and will supply clock, despite
> the telco's techs protestations to the contrary.

The PA-T3 is in the older M13 format. PMC Sierra **DOES** make chips and I 
have been assured cisco has had them ages ago in the lab that would allow a 
PA-xT3 card to run each "t3" in either M13 format or as VT1.5s (ie the way a 
cisco 15454 (Cerent) breaks out 28 T1s from an STS). cisco's sloth or 
arrogance in not providing the spiffier card has kept us inthe dark ages. 
The ideal size would be some multiple of 3 and, though you might want coax 
BNCs running at 51.x meg, *I* would prefer an OC3 interface and each STS 
could be configured as M13 format or as VT1.5s. Your Telco is demuxing these 
for you and probably with pure M13 type hardware, but also possibly is going 
through a transmux to VT1.5 format and then breaks them down toT1s.

A big DACs can handle either format. The 15454 can pass the M13 format 
through on a T3 that enters and exits as a T3 but normally can't peek 
inside. If you get stuck and have to buy the obscenely expensive 6 T3 
transmux card, you get 6 COAX M13 format T3 on the outside and 6 STSes 
inside in VT1.5 format and can haul them around as you please and with an 
XTVT matrix card, can reshuffle individual VT1.5s into any timeslot in any 
STS. It is a simple T1 DACS in your SONET network. The bummer is that 
cisco's 12 port T3 cards ONLY run 45 meg to coax and the other cards todo 
51.x meg are never on sale used inthe US at least. Newer designs from less 
arrogant vendors let each port be whichever speed you need. The 1U VT1.5 
(STS) "M13" boxes MUST have the 51.x meg speed. cisco, by never having a 
newer PA-x-T3 card and no multipurpose 12 port "T3" card, has shafted T1 
users.

The 1U "M13" box (Adtran, Telco Systems, CAC, and others) all can be had as 
dumb old M13 boxes or the newer STS types that do VT1.5s. Price is about the 
same. There is a vendor that makes a 9 mux unit that can flip to run either 
format, but I never see them for sale used.


> Subject: [c-nsp] Line Code Violations
>
>
>> I'm trying to troubleshoot a DS3 and it's really frustrating me. The 
>> local
>> side terminates on a PA-T3+ and it is barely seeing any errors, and when
> it
>> does they are CRC errors. The far side, however, is seeing gobs of 
>> errors,
>> approaching an 8% error rate at times. I don't have remote access to the
>> CSU/DSU but I do know that the CV light on it is flashing, which 
>> indicates
>> line code violations. Our equipment can only run B3ZS and I've had the
>> carrier verify that their stuff is set the same way. They say that it is.
>> I'm beginning to think that perhaps we have a bad cable and we're seeing 
>> a
>> lot of different kinds of errors in addition to the LCVs, but I just 
>> don't
>> know because I don't have remote access to the other CSU/DSU.
>>
>> I'm going to drive out there later today with my laptop to see what I can
>> see, but I thought I'd check with you guys to see if you knew of any 
>> other
>> types of issues that could cause line code violations. For the moment, 
>> I'm
>> assuming that we're just seeing a lot of different errors and some of 
>> them
>> are manifesting as line code violations, but it doesn't hurt to ask.
>>
>> I should mention that we're using c-bit framing, and the PA-T3+ is
> providing
>> clock.
>>
>> Thanks!
>> John
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