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QOS With Non-Cisco VOIP Phones

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Hi guys. I'm getting ready to implement VOIP on our LAN. I will have a PRI gateway that takes calls out to the PSTN, so I do not need to worry about WAN issues. I am going to be using non-Cisco, SIP phones, and I will have two VLAN's setup - the native VLAN (10.0.0.0/8) will be used for data, and VLAN 2 (172.16.1.0/24) will be used for voice. The SIP phones have a bridge port built-in that will connect the user's PC to the network. The phones will mark the voice packets with the appropriate DSCP tag, and pass along the data traffic without re-tagging it. The Ethernet drops will run back to two Cisco 2960 switches, that will have trunking enabled on each PC/phone port. A single Sonicwall Pro 2040 will handle routing between the VLAN's.


The question I have is regarding QOS. I know that the "auto qos voip cisco-phone" command forces the port to rely on CDP to detect a Cisco IP phone - therefore, this option will not work for me. I had planned on using the "auto qos voip trust" command on each port, but Cisco recommends using this setting only when a router or switch is hooked up to the port. The only other easy option, that I can see, is enabling QOS globally, and using the default queue settings (buffer, thresholds, etc) that the switch configures. I can then just configure each port to "Trust DSCP", and I will make sure that the DSCP-COS mappings are all set to assign voice traffic to queue 4. My question is whether I should use the modified queue settings that the "auto qos voip trust" command sets, against Cisco's recommendation, or if I should use the default queue settings that are configured when enabling QOS globally. Clearly I want to give the necessary prioritization to the voice traffic, but at the same time I do not want to bring the rest of the network to a halt by using the wrong queue settings.


I hope that I have outlined my situation well enough, but I can certainly provide more details on my config if needed. Thanks for any help that you can provide.


-Ryan

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Fabio Francisco Sun, 12/19/2010 - 21:30
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Hi Ryan,


I ended up in your post because I'm going trough the same problem. Just wondering if you could give me an advice on switch interface settings basically you are going to use trunk between sw and Ip phone. right?


I was windering if I could set the interfaces up like this:


switchport access vlan 1
switchport voice vlan 2


I think it comes down to the IP phone that I will be using. is this rright?


cheers,



Fabio

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