Cisco switches and other vendors phones

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Oct 15th, 2009
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I have a question that I just cannot find a solid answer for. Say I have a phone from a vendor other than Cisco and my switches are all 2960's. The phones support both CDP and LLDP-MED. I have the command mls qos trust cisco-phone entered on the switch port. When I plug the phone in and it exchanges CDP information with the switch, will the switch trust the cos/dscp markings or not?? Thanks in advance.

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Brian Carlson Thu, 10/15/2009 - 16:45
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If the third-party phones truly support CDP, then there shouldn't be an issue. However, the best test in this case would be to plug in one of those phones and see what happens.

stowellp Fri, 10/16/2009 - 05:41
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I would plug the phone in, make a test call. Use wireshark to check the QoS marking on the switch (egress port), that way you can be sure what is happening

unclerico Fri, 10/16/2009 - 08:19
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Thanks guys. I don't have the phones yet, but I am getting the switch ports configured. My fallback was going to be just plug them in and sniff the traffic, but hey, if someone is already doing this then why not rely on their experience, right?? Thanks a lot.

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