how to setup auto QOS in the LAN environment

[HWangLoyalty_2]

In our network environment, we already completed the Qos setup for WAN link. We would like to turn on auto qos in our LAN environment with cisco Voip phones. I also researched both document and previous topics, but I still am not clear about the configurations. Could you help me clarify it?

Access port (connected to phone): auto qos voip cisco-phone

Trunk port (Uplink to core or other switches): which command I should put?? auto qos voip trust or mls qos trust?? If mls qos trust is used, should I use mls qos trust cos or mls qos trust dscp

Access port (connected to telecomm server): which command I should put?? auto qos voip trust or mls qos trust?? If mls qos trust is used, should I use mls qos trust cos or mls qos trust dscp .

Please do not send me a link with Cisco Doc as your answer. I appreciate it for any input with your experience. 

[jonathanaxford · Accepted solution]

eHi,

You are on the right track. The simplest setup would be the following:

Access port connecting phone - auto qos voip cisco-phone

Trunk port connecting switches - auto qos voip trust

Access port connecting Telecomm server - auto qos voip trust

Next, you need to decide whether you want to trust DSCP or CoS values. Generally, I would always recommend trusting DSCP values across the network. This means that you would need to add the "mls qos trust dscp" command onto each interface as well, as by default, the auto qos command will tell the switch to trust CoS values.

That should give you a functional auto qos configuration across the board. What access layer switches are you using for this?

Many thanks

Jonathan

[HWangLoyalty_2]

Thanks Jonathan for your quick response!

About command mls qos trust dscp, will I have to every interface including in the access ports connected to phone?

In our environment, almost network devices are 3750, but there is still 3550 and 3560 as well. Any difference with 3750?

Also I think I could use them in 6500 switch ports connected to servers. Please advice!

[jonathanaxford]

Hi,

The mls qos trust dscp command will need to be entered into each interface (As far as i know there is no global command to do this)

There are differences in how each of the switches implements QoS, but auto qos should be supported on the 3550, 3560 & 3750 models. The commands you enter will be the same (auto qos voip cisco-phone etc)  although you will see differences in the configfuration that is created as the switches will implement different queueing & scheduling architectures.

The 6500 should support auto qos - although I was invloved in the config of one recently that wasn't running the correct IOS version to support it, and couldn't be upgraded so all QoS configuration was applied manually.

I know you didn't want to be pointed at any Cisco documentation, but I would really recommend the following document. It has a lot of useful information regarding Quality of Service in Cisco Catalyst devices:

http://www.cisco.com/univercd/cc/td/doc/solution/esm/qossrnd.pdf

I hope this helps,

Jonathan

[HWangLoyalty_2]

Hi Jonathan:

I still have a question about Qos related to server. In the core switch ,for example we create server VLan as Vlan2. My question is could I setup auto qos to Vlan 2? If I could, is it still required to set up auto qos for each physical switch port connected to these servers? Are there any difference?

Thanks your assistance again!!

[jonathanaxford]

Hi,

As far as I am aware, QoS needs to be setup on the physical interfaces themselves and not on VLANs/SVI's.

The actual queueing and scheduling of packets is done at a hardware level.

Many thanks

Jonathan