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Possible T1 clocking problem.

 

 

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mays at win

Apr 17, 2012, 11:46 AM

Post #1 of 5 (759 views)
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Possible T1 clocking problem.

We're setting up an HDSL4 t1 across two copper pairs. This is the first time I've ever turned up a T1 that was not telco provided. The smartjacks show the T1 as up (and extremely good quality, actually, strong signal and not a single bit error). On the CO side the T1 goes to a T3 multiplexer which is plugged into a channelized T3 card in an AS5400. On the remote end the T1 is plugged into T1 WIC in a 2600.

Both ends show the T1 interface up, line protocol is down. Encapsulation is PPP, but all I ever see are errors. I've confirmed the wiring and every other aspect of the physical layer.

Here is the show interface info from the AS5400 6 minutes after clearing counters on the interface.

AMSS1#show int serial1/0:24:0
Serial1/0:24:0 is up, line protocol is down
Hardware is DSX1
Internet address is 216.24.28.249/30
MTU 1500 bytes, BW 1344 Kbit, DLY 20000 usec,
reliability 244/255, txload 1/255, rxload 1/255
Encapsulation PPP, LCP REQsent, loopback not set
Last input 23:04:24, output never, output hang never
Last clearing of "show interface" counters 00:06:00
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 1008 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 12 giants, 0 throttles
14 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 2 abort
75 packets output, 1050 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
Timeslot(s) Used:1-24, Transmitter delay is 0 flags
AMSS1#

The interface on the remote end (t1 WIC port in a 2600 shows a lot more errors, including a lot of frame errors, for the same time period.

On the AS5400, the clocking on the t3 interface is set to take clocking from the network. Show tdm clock shows the clocking on the t1 channel in question (channel 24) as good.

AMSS1#show tdm clock

Primary Clock:
--------------
System primary is slot 1 ds3_port 0 ds1_port 1 of priority 1
TDM Bus Master Clock Generator State = NORMAL

Backup clocks for primary:
Source Slot Port DS3-Port Priority Status State
-------------------------------------------------------------
Trunk 1 2 YES 2 Good Configured
Trunk 1 3 YES 3 Good Configured
Trunk 1 4 YES 4 Good Configured
Trunk 1 5 YES 5 Good Configured
Trunk 1 6 YES 6 Good Configured
Trunk 1 28 YES 202 Good Default

Trunk cards controllers clock health information
------------------------------------------------
CT3 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1
Slot Port Type 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1
1 0 T3 G B B B G B B B B B B B B B B B B B B B B B G G G G G G

Worth noting is that the other t1's (1-6) that show up as good are all standard t1's through the telco. Channel 24 connects directly to the HDSL smartjack that goes to the remote end. I assume the AS5400 end is picking up clocking from the MUX for channel 24, but it's not clear to me what is deciding the clocking for the T1 to the remote from the mux (which is where all the frame errors are showing up) in this case.

I've tried setting the T1 on the remote side to both clock-source line and clock-source internal. No difference in either case.
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jay at west

Apr 17, 2012, 11:54 AM

Post #2 of 5 (713 views)
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Re: Possible T1 clocking problem. [In reply to]

On 4/17/12 11:46 AM, Joseph Mays wrote:
> We're setting up an HDSL4 t1 across two copper pairs. This is the first time I've ever turned up a T1 that was not telco provided. The smartjacks show the T1 as up (and extremely good quality, actually, strong signal and not a single bit error). On the CO side the T1 goes to a T3 multiplexer which is plugged into a channelized T3 card in an AS5400. On the remote end the T1 is plugged into T1 WIC in a 2600.
>
> Both ends show the T1 interface up, line protocol is down. Encapsulation is PPP, but all I ever see are errors. I've confirmed the wiring and every other aspect of the physical layer.
>
> Here is the show interface info from the AS5400 6 minutes after clearing counters on the interface.

Clocking problems will usually come up but show slips.

Things to check:

Framing - B8ZS throughout (including the mux ports)?
Linecode - ESF throughout?

And a fat-finger that had us going for a while, staring at it wasn't
immediately obvious...

"timeslots 24" isn't the same as "timeslots 1-24". :-)


--
Jay Hennigan - CCIE #7880 - Network Engineering - jay [at] impulse
Impulse Internet Service - http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV
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lee.t.starnes at gmail

Apr 18, 2012, 12:06 PM

Post #3 of 5 (708 views)
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Re: Possible T1 clocking problem. [In reply to]

I would also look at speed setting. Not all versions of IOS default to 64K
per channel.

timeslots 1-24 speed 64.

-Lee

On Tue, Apr 17, 2012 at 11:54 AM, Jay Hennigan <jay [at] west> wrote:

> On 4/17/12 11:46 AM, Joseph Mays wrote:
> > We're setting up an HDSL4 t1 across two copper pairs. This is the first
> time I've ever turned up a T1 that was not telco provided. The smartjacks
> show the T1 as up (and extremely good quality, actually, strong signal and
> not a single bit error). On the CO side the T1 goes to a T3 multiplexer
> which is plugged into a channelized T3 card in an AS5400. On the remote end
> the T1 is plugged into T1 WIC in a 2600.
> >
> > Both ends show the T1 interface up, line protocol is down. Encapsulation
> is PPP, but all I ever see are errors. I've confirmed the wiring and every
> other aspect of the physical layer.
> >
> > Here is the show interface info from the AS5400 6 minutes after clearing
> counters on the interface.
>
> Clocking problems will usually come up but show slips.
>
> Things to check:
>
> Framing - B8ZS throughout (including the mux ports)?
> Linecode - ESF throughout?
>
> And a fat-finger that had us going for a while, staring at it wasn't
> immediately obvious...
>
> "timeslots 24" isn't the same as "timeslots 1-24". :-)
>
>
> --
> Jay Hennigan - CCIE #7880 - Network Engineering - jay [at] impulse
> Impulse Internet Service - http://www.impulse.net/
> Your local telephone and internet company - 805 884-6323 - WB6RDV
> _______________________________________________
> cisco-nsp mailing list cisco-nsp [at] puck
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>
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mays at win

Apr 18, 2012, 1:49 PM

Post #4 of 5 (697 views)
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Re: Possible T1 clocking problem. [In reply to]

> timeslots 1-24 speed 64.

That was it. Thanks so much. I've been trying to figure out for days why something that should be simple was proving impossible.

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lee.t.starnes at gmail

Apr 18, 2012, 4:41 PM

Post #5 of 5 (697 views)
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Re: Possible T1 clocking problem. [In reply to]

Glad I could help.

-Lee

On Wed, Apr 18, 2012 at 1:49 PM, Joseph Mays <mays [at] win> wrote:

> **
> > timeslots 1-24 speed 64.
>
> That was it. Thanks so much. I've been trying to figure out for days why
> something that should be simple was proving impossible.
>
>
>
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