Dropped packets on VoIP network

[300yrds]

Have a customer with a blackdiamond at the core. 4 sites connect to it via fiber. One site has an Alpine and runs clean. Another site has a 5i that is connected to a Summit24 that we get our access to the network for VoIP trunking. No problems at this site either.

Another site has a 7i and we are getting packet loss. The final site had a 7i and had packet loss. It was switched out to a Alpine and still get packet loss.

Is it possible that the problem may reside in the BlackDiamond since all sites connect back to it?

Please give ideas.

 

[rn4it]

I'd start with checking the ports that the fiber is patched into, confirm that there is no rx or tx errors, at both ends Black Diamond and the 7i/alpines. You may also want to have the fiber tested that's running to the locations that are experiencing packet loss. Since you have 2 sites that are running clean, I wouldn't say it's a BD issue in general, it is possible that there is a problem with those to particular ports. My money would be on the following:
* Mismatch on port speed/duplex between BD and 7i/alpine.
* RX/TX errors on either side BD or 7i/alpine
* noise on the fiber.

 

[300yrds]

Thanks for the information. I will investigate with the on-site admin.

Thanks again!

 

[rn4it]

let me know how it works out.

 

[300yrds]

I just did some stream analysis on a 10 minute sniffer trace. I am seeing the same number of dropped packets at the same times on different conversations. This is leading me to belive that either the core (Blackdiamond) or the 7i at the remote site I was at is having trouble. I am talking up to 50 or more lost packets at a time.

I am sending the results to the customer and will update this thread as things progress.

 

[rn4it]

On either side are you receiving RX or TX CRC errors? are the port speeds and duplexing matched properly (either both set to auto or both hard set to the same speed and duplex. If so and there's no errors, during off hours run and extended diagnostics on both devices. Let me know what you find.

 

[TripleT]

I have seen something similar.

Unles there is a specific requirement tuen off autonegotiate on both ends.

I have seen, particularly when sending VoIP traffic that on occasions, if you use auto negotiate, one end will go to Half Duplex while the other stays at Full Duplex.

 

[300yrds]

Unfortunately I am having a tough time getting straight answers from the customers NET Admin. He is stating that all stats on all port show clean. We have verified that our interface matches their port interface as far as 100/full. I have asked how they have their GBIC interfaces configured and he states that he has them set to auto.

Should the GBIC interfaces on the Extreme switches be set to a hard coded 1000/full?

 

[rn4it]

My rule of thumb is always hardcode, otherwise you would have to trust them(NIC and Switch) Programers to agree on the algorisms to configure auto negotiation.