TA 900 with CRC errors on a PRI customer also have another T1 in a different TA900 on same PBX

[jlvega]

Customer want to have redundancy and wanted to have 2 different Adtrans, but one of the T1 keeps dropping with CRC ES errors.  Could it be the clock settings? 

t1 0/3 is UP
  Description: A9161495
  Receiver has no alarms
  T1 coding is B8ZS, framing is ESF
  Clock source is system, FDL type is ANSI
  Line length is 10 feet
  No remote loopbacks, No network loopbacks
  Acceptance of remote loopback requests enabled
  Tx Alarm Enable: rai
  Last clearing of counters 4d 19:14:08
    loss of frame  : 7, last occurred 20:35:12
    loss of signal : 9, last occurred 20:32:35
    AIS alarm      : 0
    Remote alarm   : 725, last occurred 00:06:51

  DS0 Status: 123456789012345678901234
              XXXXXXXXXXXXXXXXXXXXXXXX
  Status Legend: '-' = DS0 is not allocated
                 'X' = DS0 is allocated (nailed)

  Signaling Bit Status: 123456789012345678901234
                   RxA: 000000000000000000000000
                   RxB: 000000000000000000000000

                   TxA: 000000000000000000000000
                   TxB: 000000000000000000000000
                        123456789012345678901234

  Line Status: -- No Alarms --

  5 minute input rate 24 bits/sec, 0 packets/sec
  5 minute output rate 24 bits/sec, 0 packets/sec
  Current Performance Statistics:
    47 Errored Seconds, 0 Bursty Errored Seconds
    0 Severely Errored Seconds, 0 Severely Errored Frame Seconds
    0 Unavailable Seconds, 0 Path Code Violations
    0 Line Code Violations, 47 Controlled Slip Seconds
    0 Line Errored Seconds, 0 Degraded Minutes

  TDM group 1, line protocol is not set
    Encapsulation is not set

sh event history

2018.05.01 11:15:17 T1.t1 0/3 CSS 15 min threshold exceeded
2018.05.01 11:17:48 T1.t1 0/3 Yellow
2018.05.01 11:17:48 INTERFACE_STATUS.t1 0/3 changed state to down
2018.05.01 11:17:48 ISDN.EP     PRI  1  D channel is DOWN
2018.05.01 11:17:48 ISDN.EP     PRI  1  D channel is DOWN
2018.05.01 11:17:48 TM.T02 23 IsdnTmStateInboundConnected - rcvd unexpected CallRelease
2018.05.01 11:17:48 TM.T02 23 IsdnTmStateIdling - clear trunk appearance
2018.05.01 11:17:48 TM.T02 21 IsdnTmStateInboundConnected - rcvd unexpected CallRelease
2018.05.01 11:17:48 TM.T02 21 IsdnTmStateIdling - clear trunk appearance
2018.05.01 11:17:48 TM.T02 0 Taking 23 b-channels out-of-service

2018.05.01 11:17:48 TM.T02 23 tachgClearing processed by IsdnTmState base
2018.05.01 11:17:48 TM.T02 21 tachgClearing processed by IsdnTmState base
2018.05.01 11:17:49 INTERFACE_STATUS.pri 1 changed state to down

[stunorman]

The 47 Controlled Slip Seconds are a strong indicator that there is not a proper clock on this circuit, both sides are trying to slave off of the other side.

Change the clock setting on your end. It should clear up your issue.

[jlvega]

How?

I tried to remove the line "Clock source is system" of the T1 configuration and it did not remove it with the no command.

[Anonymous]

Get into the router GUI and choose Current System Clock Source from the System Summary Tab and choose your timing source there,

[Anonymous]

jlvega, if T1 0/3 is the only T1 connected, it should be your timing source.

[jlvega]

The problem is that they have one T1 in Adtran A and one T1 in Adtran B on the same PBX.  So the PBX has 2 T1 trying to be the timing source.  Is it possible to make that work (2 Atrans going into one PBX)?

[Anonymous]

Ahhh, I see that now. So they want router redundancy? I'd rather have the two T1s as 0/1 and 0/x without bonding them, and set it up on a failover. Unfortunately, I don't know of a way to disable the time source of a 900. (series)

[jlvega]

Thanks anyway, I appreciate your help.

[jayh]

This setup gets tricky because each device wants to have a single timing source and each T-1 must have a single timing source. Normally, the network side is the clock and the user side syncs from the network.

What you can do here is to make the PBX the clocking source. Set its clock to internal. Exact syntax depends on the PBX documentation. Then, on each of the two TA900 routers, configure timing-source T1 0/3 so that they clock from the PBX.

[yorcram]

Telco normally want to be the timing source for PRIs. A similar setup was done here using two NV6250s. If you have free T1 ports on the e900 you can try the following as this:

First NV6250

interface t1 0/4

  description connected to unit2 0/4 for timing reference

  tdm-group 1 timeslots 1-24 speed 64

  no shutdown

Second NV6250

interface t1 0/4

  description connected to unit1 0/4 for timing reference

  tdm-group 1 timeslots 1-24 speed 64

  no shutdown

Also Add to second and third nv6250:

timing-source t1 0/4

Crossover T1 cable needed.

[yorcram]

timing-source t1 0/4

Just to be clear the above command is added to the second and every other slaved switch. It is not added to the Primary switch.

[jayh]

yorcram wrote:

Telco normally want to be the timing source for PRIs.

Absolutely agreed. In this case, telco isn't involved on any TDM circuits. OP has SIP from telco. The only T-1s are local, one from each of two TA900s to the PBX. Customer wants redundancy should either of the TA900s fail. Normally the TA900 would source clock and PBX would slave to it. In order to achieve redundancy, we can generate clock from the PBX and sync both TA900s to the PBX clock. Now, should either TA900 fail completely, the other will stay in sync with the PBX.