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QoS with 2524+9300

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Domenico Viggiani
Super Advisor

QoS with 2524+9300

Hi,
I have 2524s at network edges and 9308s at core.
I'd like to implement some form of QoS for VoIP services.
I noticed that 2524s support only port-based 802.1p. Is it true?
Is ToS supported in some form?
What is the best way to implement VoIP with this scenario?

Thanks
8 REPLIES
Matt Hobbs
Honored Contributor

Re: QoS with 2524+9300

Hi Domenico,

Check out the ProCurve VOIP cookbook - http://www.hp.com/rnd/pdfs/VoIP_Cookbook.pdf

With the 2524 if you're going to have PC's connected to the phones in a different VLAN, then you should be okay as long as the phones insert an 802.1p flag for the voice traffic.

Otherwise if you have phones only, then you can force the port's priority only as you have suggested.

Matt
Domenico Viggiani
Super Advisor

Re: QoS with 2524+9300

I'm planning to have access switches dedicated to phones only.
At the core (9304), do I need to map 802.1p (level 2) priorities to DSCP (level 3), if server and phones are on different subnets?
Matt Hobbs
Honored Contributor

Re: QoS with 2524+9300

Generally you only need to configure DSCP if you're going across a link (mainly WAN) that does not support 802.1Q tagging.

When a 9300 routes from one VLAN to another, it will retain the 802.1p priority within the tag and just change the VLAN ID.

So for all your VLANs that are involved with voice, as long as you keep them tagged between all your switches, you should be okay.
Domenico Viggiani
Super Advisor

Re: QoS with 2524+9300

To retain priorities end-to-end, do I need to use a tagged link for my VoIP PBX server too?
Then not 802.1Q-tagged devices will be able to reach it?

Thanks again.
Matt Hobbs
Honored Contributor
Solution

Re: QoS with 2524+9300

You should treat it like you would a phone really.

It depends on what switch you'll be connecting it to. If connecting to a 2500, you'll want to set the port priority, or if the VOIP server is capable of tagging and inserting a priority tag, then that's also fine.

Alternatively if connecting to the 9300 you can configure the qos priority on the VLAN (which you'll want to do in the core anyway), and keep the port untagged. You could even prioritise based on the IP address.

Matt
Domenico Viggiani
Super Advisor

Re: QoS with 2524+9300

Ok, I used port priority on 2524s for all devices.
How can I check if priority is working on the full path?
Can I dump packets of interest on 2524s and 9304s and look at vlan tag?
Matt Hobbs
Honored Contributor

Re: QoS with 2524+9300

Hi Domenico,

The only way I know to check if the priority tags are being inserted, is to perform a packet capture with ethereal.

One way is to put a hub in between two switches, and connect your ethereal machine into the hub. You can also set a mirror-port on your switch. That port will need to be a tagged member of the VLAN you are interested in. I would then monitor the uplink port. Sometimes the hub is just easier...

Next, depending on your NIC you may not be able to see the VLAN tag if using Windows. If you have an Intel or Broadcom NIC though you're in luck - http://wiki.ethereal.com/CaptureSetup/VLAN

Otherwise I've found if you run Ethereal on Linux you can always see the tag.

Matt

Domenico Viggiani
Super Advisor

Re: QoS with 2524+9300

Sometime, I'm really surprised by simplicity!
You are really a guru.

Thanks again