Solved

IP Telephony:  Echo using g711ulaw

Posted on 2004-04-05
5
786 Views
Last Modified: 2012-06-27
Our oganization has implemented a Cisco AVVID solution.  We are having echo problems with certain branch locations.  The problem exists for both internal and external calls.  We've got point-to-point T1s for each location and we're using codec g711ulaw which is uncompressed voice.  I've been troubleshooting the issue by applying echo-cancellation on the PRI interfaces which hasn't changed the performance.  Since the problem aslo exists for internal calls I believe the problem isn't with the PRI.  What steps can I take to troubleshoot this probem further?  Any suggestions on what the problem may be?

Call Manager version:  3.3(2)
Gateways:  H323
Phone type:  7960
Switch type:  Cisco 3550 with inline power

Thanks a lot!
0
Comment
Question by:wendelina
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
5 Comments
 

Expert Comment

by:shautayl
ID: 10759334
do you have the ability to ping another computer on the connection with the t1,  if you are, try to ping the other computer and see if you are getting repeating packets or packet loss.... that could be the cause of the issue or even latency... ping the ip phone server to see if that may be causing the issue.

shautayl
0
 

Author Comment

by:wendelina
ID: 10759694
I've run extended ping scans using a 1500 MTU packet size.  The speed is less that 30 ms and the result is 100%.  The voice server (CCM) is designed to set-up the calls, not facilitate the conversation.  That is a peer-to-peer function.  That's what is confusing me.  Our network is a hub and spoke topolgy with plenty of bandwidth to handle the 80k voice-calls.  I can understand echo from a PRI, but internally?  All phones are set to 100/Full, so 80k is nothing.  Thanks for the reply!
0
 
LVL 2

Accepted Solution

by:
enkrypter earned 500 total points
ID: 10762228
Got any QoS or CoS turned on?  YOu might want to play with that.  Are you currently prioritizing voice packets.  Also, check out the statistics on your VLANs if you have any.  Make sure spanning tree is running properly or whatever other VLAN protocol you may have.  VLANs are sometimes a bottleneck for VOIP rather than a helper.

I'd play arround with compression, like G.729a, and some QoS.  What is your core switch?
0
 
LVL 12

Expert Comment

by:public
ID: 10762981
Yes echo problems are usually due to QOS issues.
0
 

Author Comment

by:wendelina
ID: 10766210
I have begun to play with qos a bit, am still awaiting the response from my customer.  I have a 4507 core switch.  Voice packets have priority over all other packets up to the full bandwidth to our sites.  Thanks for the responses, I'll see if the qos helps then award you your points if it does!
0

Featured Post

Create the perfect environment for any meeting

You might have a modern environment with all sorts of high-tech equipment, but what makes it worthwhile is how you seamlessly bring together the presentation with audio, video and lighting. The ATEN Control System provides integrated control and system automation.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

PRTG Network Monitor lets you monitor your bandwidth usage, so you know who is using up your bandwidth, and what they're using it for.
Make the most of your online learning experience.
This video gives you a great overview about bandwidth monitoring with SNMP and WMI with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're looking for how to monitor bandwidth using netflow or packet s…
In this video we outline the Physical Segments view of NetCrunch network monitor. By following this brief how-to video, you will be able to learn how NetCrunch visualizes your network, how granular is the information collected, as well as where to f…
Suggested Courses
Course of the Month5 days, 2 hours left to enroll

636 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question