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Reading QoS Tags

We have a VoIP network that goes over a private WAN connection to a central datacenter where the Voice Gateways are located. We are having reports of "echo" and "darth vader voice" every once in a while when the calls are made to the PSTN, but never issues when the calls are site to site.

I don't think that our QoS tags are making it across the carrier WAN to our gateways, and I need to prove this.

How can I make sure that QoS is working properly? How can I make sure that the packets are QoS tagged with DSCP markings?

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Re: Reading QoS Tags

one easy way to find out if the packets are marked properly is to use a sniffer.

get the best freeWare sniffer out there at:

http://ethereal.com/download.html

you can decode the voice stream packets and verify if/what DSCP is set too. this is quik and accurate.

if you don't see DSCP on the far side of the WAN, try the local side and so forth until you find the location that DSCP is being stripped (or if it's not set at all)

if it gets down to it, unplug the PC from the back of the phone and plug your sniffer PC into there to sniff directly from the phone.

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