cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
3075
Views
14
Helpful
24
Replies

PRI Slips and Error

balukr
Level 2
Level 2

We have a customer connecting their Nortel PBX via PRI to a 2851 router with VWIC2-2MFT-T1 on the Cisco CM side.

PRI is up and we are able to make calls bothways but the PRI is flapping (up and down every 10 mts). I checked ("sh controller t1") the router and saw just slip and error seconds go up but Line code and path code violation stays clean with 0 errors.

2851 router is providing clock to PBX here is the config

clock timezone AZ -7

network-clock-participate wic 0

ip subnet-zero

!

!

ip cef

!

!

no ip domain lookup

!

isdn switch-type primary-ni

!

voice-card 0

no dspfarm

!

controller T1 0/0/0

framing esf

clock source internal

linecode b8zs

pri-group timeslots 1-24 service mgcp

!

interface Serial0/0/0:23

no ip address

isdn switch-type primary-ni

isdn protocol-emulate network

isdn incoming-voice voice

isdn bind-l3 ccm-manager

no cdp enable

------------

One thing I couldn't do is one of the clocking command "network-clock-select" if I try it comes back with an error "*** Controller T1 0/0/0 is NOT deriving Clock from Line".This is the only T1 PRI connected on this router and I have no other T1 to point for clocking.

How do I fix this slip error so the T1 won't flap anymore and stays clean.

Thanks for your help.

24 Replies 24

paolo bevilacqua
Hall of Fame
Hall of Fame

Hello I've answered this already in the voice forum.

Rick Morris
Level 6
Level 6

I had a similar issue.

Make sure that the Framing and Coding are the same at both ends and what you ordered from the LEC.

If you ordered a point to point T ESF/B8ZS then you need to make sure that it is set up this way and not SF/AMI

Also make sure all the channels are set up.

The router should be providing clocking and the nortel should be getting clock from the network.

We checked it is setup correct on both ends I upgrade the IOS to latest version just in case still no luck.

With this type of issue it could be the LEC causing the SLIP.

I would have them run some end to end testing with their T-Bird or like tester to see if it is a repeater, mux, or something else in "Telco Land"

I don't see any other way around it. At leas if they find nothing you can rule out the Telco portion.

Oh wait, is this going through telco or is it a direct cable from the Nortel to the 2811?

It is a direct T1 crossover cable from nortel to 2851 ISR

molesworthcco
Level 1
Level 1

set your clock source to external so you pull it from the telco provider...I had the same issue with setting my mgcp to internal...flopping and excessive slips.

Seems hard to make people understand that there is no telco in this design :)

It's just a generic term for a TDM system (telco could be a company, or in my case, I'm a telco because I administer the Nortel DMS-100). Anyway, if the nortel is not pulling timing from another source, it has to be configured to pull the time from the router...see below

>tb synclk

>lis all

TOP

CLKKEY CLKDATA OFFCDATA

-----------------------

0 STRAT3 SLAVE DTC 0 0 0 DTC 0 2 1

BOTTOM

>

Your voice tech can point his time source to the router links. Then he can manage them via MAPCI;MTC;MS;CLOCK

Sorry we misunderstood your term here, anyways they do have a T1 PRI coming from Telco (real Telco !!!) connected to there PBX and this is the second T1 for Tieline between Cisco 2851 and PBX.

Is this config still valid in that case or no?

I just want to check beofre I send this to him.

Hmmm...strange that he doesn't already have a timing source...especially since there is already a connection to another CO...if my clock drifts just a little, it throws my commercial links out of wack...this usually happens when I lose my timing source (pulled via ss7 from a distant multifunction switch). If the system is a DMS/MSL type switch, then yes the table listed is where he can datafill the timing links. However, if it is a Meridian1, the config will be quite different. I have the manuals for the Meridian1 and can find it out where to do it. I do know that LD 60 is the level for controlling synchronization on the time source, but it still has to be provisioned...possibly in LD 22.

anthony.king
Level 1
Level 1

The Nortel PBX can only have one clock source. If there is already a PRI or T1 connected to the PBX from a Telco, then the clock controller on the PBX should be deriving the clock from that. In that case, the PBX is providing clock on the line to your router and you should set your clock source to 'line'.

There is no Telco here it is a direct cable from PBX to 2851 router.I tried to configure router side as line for clocking then D channel never comes up.

I talked to the PBX tech he said if he needs to configure his side as master for clocking then he has to set his switch type as DMS-250 whcih I'm not sure why he can't do NI2.

I may move to a differnt card in the same router and see that helps.

I'll keep you posted.

We replaced the cable didn't help , since we have two VWIC's on the router we moved the T1 to second VWIC card that didn't help either. I tried with MGCP and H323 both didn't work so I'm not sure what we are missing in the Nortel side. I'm sure it is a minor thing but we don't know what it is.

I'll keep you guys posted.

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Innovations in Cisco Full Stack Observability - A new webinar from Cisco