QoS for Non-Cisco System

[cabellmiller]

OK, so I'm going to sound ignorant, but only because I am.  I have been given the task of setting up QoS on our network to support a non-Cisco IP Phone system.  My question is, can I set up AutoQoS globally on a switch, or do I have to set it up for each port that will receive a phone?  I'm using the "voip trust" command on my trunked ports, and setting native vlans on each port, along with vlan access to my data vlan(s) and my voice vlan.  Should that be enough to provide basic QoS for voice or do I need to do some thing on my router (6506) as well?

As I said, I know I'm sounding ignorant, but we're a small group and I'm learning as I go along here.  Any assistance would be GREATLY appreciated.

Thanks!

Cabell Miller

SysAdmin

St. Mary's County Government

Maryland

[InayathUlla Sharieff]

Hi Cabell,

You can use auto QOS feature , auto QOS automatically generate the reuired commnd for

voice traffic priortization

Personally, I would rely on the trusting DSCP assuming it's using EF (46). If you trust COS then you'll need to modify your cos-dscp map as well otherwise the switch will rewrite DSCP to 40 each time possible messing things up on another device!

But look at the specifics for trunk setup, allowed vlans, etc. Since CDP can't be used for passing voice vlan info, you will use your DHCP server options to pass appropriate information for the phone to download.

On newer versions of software (at least on 3560/3750, but I THINK 2950 as well) you will get LLDP support which is the industry standard version of CDP giving you some similar capabilities.

Eg:The following document  Thats states the following "By default, the CDP is enabled on all interfaces. For auto-QoS to 

function properly, do not disable the CDP"

  http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12119ea1/

2950scg/swqos.htm#1131278

This sure applies to CISCO IP Phoens because When you enter the auto 

qos voip cisco-phone

interface configuration command, the trusted boundary feature is 

enabled. It uses the

Cisco Discovery Protocol (CDP) to detect the presence or absence of a 

Cisco IP phone. When

a Cisco IP phone is detected, the ingress classification on the 

interface is set to trust

the QoS label received in the packet. When a Cisco IP phone is absent, 

the ingress

classification is set to not trust the QoS label in the packet.

What this means is that If you plan to use IP Phones and decide to 

disable CDP, auto Qos

will not work as expected. WIth Non-Cisco IP phone this restriction is 

not applied. With

Avaya phones even if CDP is enabled or disabled it will not make any 

difference as the

list of commands that automatically is generated when you type "auto 

qos voip cisco-phone"

is mls qos trust cos and that is sufficient to make the AVaya phones to 

work. Disable CDP  on the interface and follow the direction in the URL  .

HTH

Regards

Inayath

*Plz rate if this is helpfull.

[cabellmiller]

OK, I understand some of that.  I am going to be using an Avaya system.  That said, I'm assuming that on each uplink trunk (on my 6506 router or 3650 switches), and on each port that I will have a phone attached, I need to use the "auto qos voip trust" command, and need to have the DHCP options set correctly (option 242, I think.. but I have it written down somewhere).  Does that about sum it up?

Thanks!!!!

Cabell