[c-nsp] DS3 mux issues

[Jay Hennigan]

Justin Shore wrote:
> Larry Smith wrote:
>>>   t1 26 channel-group 0 timeslots 1-24
>>>   t1 27 channel-group 0 timeslots 1-24
>>>   t1 28 channel-group 0 timeslots 1-24
>>>
>> controller T3 5/0
>>  framing m23
>>  clock source line
>>  cablelength 10
>>  t1 1 channel-group 0 timeslots 1-24
>>  t1 2 channel-group 1 timeslots 1-24
>>  t1 3 channel-group 2 timeslots 1-12
> 
> Morning, Larry.  Do you know if the channel-group # is significant to 
> each DS1 or does the channel-group # have to be unique across the DS3? 
> I'm thinking that it's unique to the DS1 so that you can create X number 
> of channel-groups on a DS1 if needed but I'm not 100% on that.

It is per T-1, so you can make them all channel-group 0 if you want. 
Makes finding the sub-interfaces easier.


>>  t1 1 clock source Line
> 
> Do you think I should generate clocking on our router or on the mux?  We 
> don't have an external clock source in that CO.  I expect to have up to 
> a dozen different M13s connected to this 7206 as time goes by.  Would it 
> be a problem if the 7206 received clocking on each DS3 from each of the 
> muxes or would that screw things up internally?  At this point I don't 
> expect to get handed a T1 w/ clocking from the RBOC.  All the CPEs will 
> be line of course.

Do you control both ends of the T3 link?  If the other end is a 
carrier-supplied mux, then our best practice is to clock the aggregate 
T3 by line and have the carrier's BITS clock drive the T3.

Then on the router clock each individual T1 internally on the 
channelized T3 card at the aggregate router end. Have the remote T1 
routers clock from line.

If you clock the individual T1s from line on the DS3 mux, then either 
the tail-end router or the T1 carrier in between must source clock. 
This is not the usual scenario.

In crude graphics:

Carrier BITS -> Carrier T3 -> your CT3 card -> T1 line -> tail router.



>> On your virtual, what does it show:
> 
> 7206:
> Serial1/0/1:0 is down, line protocol is down
>   Hardware is PA-MC-2T3-EC
>   Internet address is 1.1.1.1/24
>   MTU 1500 bytes, BW 1536 Kbit/sec, DLY 20000 usec,
>      reliability 253/255, txload 1/255, rxload 1/255
>   Encapsulation HDLC, crc 16, loopback not set
>   Keepalive set (10 sec)
>   Last input 18:15:59, output never, output hang never
>   Last clearing of "show interface" counters 00:00:07
>   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  0/1/16 (active/max active/max total)
>      Reserved Conversations 0/0 (allocated/max allocated)
>      Available Bandwidth 1152 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, 0 giants, 0 throttles
>      0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
>      0 packets output, 0 bytes, 0 underruns
>      0 output errors, 0 collisions, 1 interface resets
>      0 output buffer failures, 0 output buffers swapped out
>      0 carrier transitions alarm present
>   VC:0 Timeslot(s): 1-24, Transmitter delay 0, non-inverted data
> 
> 2811:
> Serial0/1/1:0 is down, line protocol is down
>   Hardware is GT96K Serial
>   MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec,
>      reliability 252/255, txload 1/255, rxload 1/255
>   Encapsulation HDLC, loopback not set
>   Keepalive set (10 sec)
>   CRC checking enabled
>   Last input 18:33:23, output 18:33:13, output hang never
>   Last clearing of "show interface" counters 19:36:46
>   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 1152 kilobits/sec
>   5 minute input rate 0 bits/sec, 0 packets/sec
>   5 minute output rate 0 bits/sec, 0 packets/sec
>      39 packets input, 3582 bytes, 0 no buffer
>      Received 39 broadcasts, 0 runts, 1 giants, 0 throttles
>      16 input errors, 16 CRC, 14 frame, 6 overrun, 0 ignored, 8 abort
>      40 packets output, 3606 bytes, 0 underruns
>      0 output errors, 0 collisions, 1 interface resets
>      0 output buffer failures, 0 output buffers swapped out
>      2 carrier transitions
>   Timeslot(s) Used:1-24, SCC: 1, Transmitter delay is 0 flags
> 
> 
> Both are configured only with an IP and are unshut.

Set clock internal on the T1 channel on the CT3 card, it will probably 
come up.  Paste the output for show controller for that T1 on the 7206 
if that doesn't fix it.

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