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New Member

PRI Loopback diag

I have a vwic-MFT-1T1 connected to a PRI from Verizon. T1 is down, Verizon has tested and they believe line is working fine. I can see a lot of LCV and PCV. No alarms.

What exacly a loopback diag do? is it a local loop or remote?

I have a diag loopback on my T1 controller and I ran BERT test. The results are:

T1 0/0/0 is up. (Diagnostic Loopback)

BERT is done on the controller. The result of last time is

DSX1 BERT status : done

DSX1 BERT pattern : QRSS

DSX1 BERT sync count : 13

DSX1 BERT interval : 1 min

DSX1 BERT time remain : 0 min 0 sec

DSX1 BERT total errs : 81

DSX1 BERT total k bits: 77970

DSX1 BERT errors (last): 0

DSX1 BERT k bits (last): 3282

Does it mean a problem in the line? is it looped up to x-demarc? up to demarc/smart jack? up to remote?

Any ideas?

Thanks!

6 REPLIES

Re: PRI Loopback diag

Problem appears to be with the vwic. Loopback diag is local to the box i.e looped up to the CSU/DSU.

You might want to try reloading the router as I have seen reload clear problems with vwic.

Pls. rate all helpful posts.

HTH,

Sundar

New Member

Re: PRI Loopback diag

I have reloaded the server many times. It didnt fix it. So loopback diag means it loops the PRI link towards the router? bits never leave the VWIC port if it's in loopback diag?

If i physically disconnect the link from the port, I'll get the same results with loopback diag?

Thanks!

Re: PRI Loopback diag

Yes, that's correct.

I am afraid you would have to replace the VWIC.

--Sundar

New Member

Re: PRI Loopback diag

Some more debug info:

#loopback diag

Apr 20 23:36:41.370: %CONTROLLER-5-UPDOWN: Controller T1 0/0/0, changed state to

up

Apr 20 23:36:41.370: ISDN Se0/0/0:23 SERROR: service_queue_from_physical_layer:

got ISDN_PH_ACT_IND on an active interface?

Apr 20 23:36:41.370: ISDN Se0/0/0:23 Q921: L2_EstablishDataLink: sending SABME

Apr 20 23:36:41.374: ISDN Se0/0/0:23 Q921: User TX -> SABMEp sapi=0 tei=0

Apr 20 23:36:41.374: ISDN Se0/0/0:23 Q921: User RX <- BAD FRAME(0x00017F)

Apr 20 23:36:42.370: ISDN Se0/0/0:23 Q921: User TX -> SABMEp sapi=0 tei=0

Apr 20 23:36:42.370: ISDN Se0/0/0:23 Q921: User RX <- BAD FRAME(0x00017F)

Apr 20 23:36:43.370: ISDN Se0/0/0:23 Q921: User TX -> SABMEp sapi=0 tei=0

Apr 20 23:36:43.374: ISDN Se0/0/0:23 Q921: User RX <- BAD FRAME(0x00017F)

Apr 20 23:36:44.370: ISDN Se0/0/0:23 Q921: User TX -> SABMEp sapi=0 tei=0

Apr 20 23:36:44.370: ISDN Se0/0/0:23 Q921: User RX <- BAD FRAME(0x00017F)

Apr 20 23:36:45.370: ISDN Se0/0/0:23 Q931: Ux_DLRelInd: DL_REL_IND received from

L2

New Member

Re: PRI Loopback diag

I think you're right and the brand new VWIC is the problem. Just to make sure, can you tell me if this config is correct?

I have a 2811 with 12.4.4XC1 and PVDMs for only 16 channels...

network-clock-participate wic 0

!

isdn switch-type primary-ni

!

voice-card 0

no dspfarm

!

controller T1 0/0/0

framing esf

linecode b8zs

cablelength short 133

pri-group timeslots 1-16,24

!

interface Serial0/0/0:23

no ip address

encapsulation hdlc

isdn switch-type primary-ni

isdn incoming-voice voice

isdn send-alerting

no cdp enable

!

voice-port 0/0/0:23

!

Re: PRI Loopback diag

Looks good to me.

Pls. rate all helpful posts.

HTH,

Sundar

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