srw224g4p source ip address based QoS

[franalcala]

Hi,

On a small LAN built with 3 cascaded srw224g4p (through the GbE ports) there will be a number of VoIP devices with known IP addresses. I need to guarantee minimum latency to those devices.

The setup I have thought is:

- Define one ACL (Action: Permit, add all Source IP addresses of VoIP devices).

- Don't bind the created ACL to any port (in Security).

- Under QoS tab:

     - DiffServ Settings:

          Create a Class, define its rule as the created ACL.

          Create a policy for that Class, set CoS=6

     - DiffServ Port Binding:

          Bind the created policy to ports (It seems that there is a limit of 12 ports that can be binded to a policy)

I am leaving all other QoS settings unchanged (WRR, CoS to QoS, etc)

My questions:

Will this work?

Any suggestions to improve?

Any better way to achieve this?

Best regards

[David Hornstein]

Hello Francisco,

Why not try something simple first.

My idea is, that if your VOIP devices are smart enough to use DSCP at Layer 3, why not try to simply use that in BASIC QOS.

Select trust DSCP as per the screen capture below, but remember to scoll to the bottom of the screen and save your settings.

Even though my switch is a eight port switch the functionality should be almost identical to your 24 port switch.

it would be nice if the VoIP gateway could also set a DSCP for returned packets back into the switch.

Then maybe check out the DSCP to Egress queue mapping and make sure that this sits your needs.

then setup WRR if you wish or try with strict priority queuing if you wish, it's probably strict priority queuing by default.

. 

But please remember to save the settings at each step,  by scrolling down to the bottom of the page and click on save.

That's the easiest thing to do. But it assumes that your VoIP devices can set and send out a DSCP.

give it a try.

regards Dave

[franalcala]

Dear Dave,

Thanks for your reply. Unfortunately the VoIP devices do not set the TOS field in the header and hence I understand I cannot use DSCP. That is why I need to implement QoS based on addresses.

Best regards

[David Hornstein]

Hi Francisco,

What about class of service (COS).  Can your phones set COS bits ?

If so why not just trust COS as best effort data traffic coming in on untagged  vlan1 will not have the ability to set COS bits.

regards Dave