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Beginner

Difference between "auto qos trust" and "auto qos voip trust"

I've a doubt, maybe someone can help me to clear it out...

Are there any differences between the autoqos commands on a WS-C2960S switches (or in any other series)? Follow the commands:

- auto qos trust

- auto qos voip trust

I was checking the documentation on this link:

http://www.cisco.com/en/US/docs/switches/lan/catalyst2960/software/release/12.2_55_se/command/reference/cli1.html#wp11888965

And couldn't find any great difference between the two commands, as far as I could see they'll set the Ingress and Egress queues the same way.

Are there any differences between those two commands (auto qos trust and auto qos voip trust)? If so, when should I use one and the other?

Thanks!

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Contributor

Hi,

your understanding is correct. There is NO a major difference between the two. the real difference is telling to your switch who he is going to trust. It can be quite different from a security point of view to trust a trunk or to trust a trunk (another switch or another router).

Remember that another difference in defining one or the other command could be on the design of the network more than on the implementation itself.

Hope it helps

Alessio

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Beginner

We started getting voice call issues on a 3750 stack, that we weren't getting at other sites with identical hardware and IOS. The config had been entered the same "auto qos voip trust" on each interface, but when you did a show run, it had become "auto qos trust".

I spotted this line in the config, that wasn't on the other stack: auto qos srnd4

So typed: no auto qos srnd4

Then reapplied auto qos voip trust to each interface.

Problem solved.

According to

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_55_se/configuration/guide/swqos.html

srnd4 is for Enchanced Auto-QoS for Video, Trust and Classification.

But unfortunately it seems to have an adverse effect on auto qos for voip.

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