Intermittant issues

[ethereal112]

CCM 4.3 during a call the conversation will cut out for 3-4 seconds, then will come back. It spontaneous and doesnt matter if your 10 seconds or 10 minutes into the call. I've done a drop and insert on the circuit, I've had the local telco come out and complete a repair, had the network engineer check the bandwith. Replaced the cable between the router and switch. Had QoS added to all switch ports. I dont know what else to try, anyone have an idea? and it isnt system wide, this location has a point to point T1 and over the past month been having these issues. Also since the call keeps cutting in and out the fax's wont go thru.

 

[whykap]

you said you added QoS on the switch ports. what about the WAN link? This sounds like a QoS issue to me and that is where you need start.
Cutting in and out means you are dropping packets and as you know voice will not be retransmitted as it would be out of sequence anyway.

 

[ethereal112]

That's a good point. I didnt even check with the Net admin to see if he had QoS on the WAN link. I just asked him and his reply was no. By anychance is QoS that same for all VoIP platforms? like NEC and Cisco. The reason I'm asking is because we have NEC and our Admin didnt know the QoS commands for Cisco, so he went ahead and added QoS commands that NEC gave him.

 

[pndscm]

This could also be a T-1 problem with slips or other errors. Be sure the T-1 is clean in both directions.

 

[ethereal112]

I've already tested the circuit with my T-berd at the Demarc and thru the house cable. Local telco tested and verified no errors. The Network Admin verified thru the router interface he has no errors. QoS on the WAN link is the only item left to try and resolve our problem.

 

[jeter]

If the T1 interface is clean, I would look at the amount of traffic and diffently deploy some QOS giving voice priority.


Go Army!
Tek-TIP Member 19,650

 

[ethereal112]

Well we've already checked the bandwidth, at the most 1/3 of the circuit bandwidth is in use. So the layout looks like this! Site A to Site B with a point to point T1 that has tested clean. Site B to site C with another point to point and had tested clean but site C is where the problem is occuring. The Call Manager and circuits are mine for administering and the network switches and routers are someone elses to take care of.

 

[bigchiefdan]

I know you are dealing with t1s, but have you checked the premis grounding?
Its a long shot, but I have seen a few instances where equipment is not properly grounded. or appears to be grounded, but the facilities begin having issues due to age or repairs.

Again, long shot and likely not the case but it jogged my memory.

 

[Iwontremember]

DSP's?

Hope this helps.

 

[ethereal112]

That could be a possibility! We are going to be replacing the house cable from the Demarc to the CPE. Were going to install lightning protecters and add grounding to that block. Thanks for the tip......

 

[whykap]

If it was a bad cable from the CPE to the smart jack you'd be taking slips and seeing errors on the controller which would cause the voice issues. However you said it's running clean, eliminating that issue altogether.
It could also be DSP's as iwontremenber mentioned that are failing or something.
The fact that you are using only 1/3 of the bandwidth does not mean you don't need QoS on the WAN link. All it takes is a 3 second data burst and your voice quality degrades.

You need to make sure you have QoS configured correctly with voice taking priority otherwise you are spinning your wheels. On both ends of the WAN circuit!!

 

[ethereal112]

What about the QoS commands, is it the same for all platforms? I had mentioned that we also have NEC VoIP and our Net. Engineer put those QoS commands on all the switch ports for CUCM IP units.

Thanks for all your responses I greatly appreciate it guys!!!