QoS on 2600 and 2800 series switches

[Andy Haigh_1]

I am about to setup QoS based on port numbers for a SIP based VOIP solution. The ports I need to apply QoS to are:

SIP 5060 to 5061
RTP Phone 2222 to 2268
RTP Gateway 6000 to 6292
RTP HMP 49152 to 49212

Is it possible to enter these ranges using the qos udp-port command?

Or is there a better of doing this?

Thanks

Andy

[Matt Hobbs]

With the qos udp-port command, my understanding is that you can only specify 15 individual ports, which is not going to be enough.

What I would recommend instead is setting a dedicated voice VLAN and prioritising that:

Syntax: vlan < vid > qos priority < 0 - 7 >

[Andy Haigh_1]

Hi Matt,
The problem with that is the PC's are connected via the same port. The phones have a two port switch built into them. I believe they already set the 802.1p settings to 5 for SIP and RTP. Can I use these settings? The Gateway and server I can look at providing priority on the Switch Port.

The Phones are Polycom 301's and 501's and we are using Intel HMP software on the server. The media gateway is either going to be a Quintum or an Audiocodes.

Thanks

Andy

[Matt Hobbs · Accepted solution]

Hi Andy,

Check out these two polycom pages:

VLANs and Polycom® SoundPoint® IP
Desktop IP Telephones:
http://www.polycom.com/common/pw_cmp_updateDocKeywords/0,1687,3541,00.pdf

Optimization for Polycom SIP Phones (scroll to 'Audio Quality Issues and VLANs':
http://eknowledge.polycom.com/SRVS/CGI-BIN/WEBCGI.EXE/,/?St=11,E=0000000000004065646,K=8932,Sxi=9,Case=obj(41257)

Most importantly it says this:

General Operation of VLANs
All Polycom SoundPoint IP models support the optional use of 802.1q/p tags both for VLAN separation as well as QoS.
By default, the phone will tag all traffic coming from the phone with a null 802.1q VLAN ID. If a VLAN ID value is configured or learned as described below, it will be inserted into the tag of all packets generated by the phone. A different QoS value may be configured, but this is not
recommended.
If a PC is connected to the phone, all packets generated by the PC will be passed through unmodified, regardless of the presence of an 802.1q/p tag or its contents. Since PCs do not typically
tag frames, this means they will be on the native VLAN.

It also goes on to say: "By default, the phone sends all audio packets with 802.1p tag and IP Precedence values of 5"

What this means is that it is using IP ToS.

So there are 2 ways you can optimise the traffic here. On the most basic level, you could just enable this command on your default/native VLAN (usually VLAN 1):

Syntax: qos type-of-service ip-precedence

This will make the switch look for the ToS field and apply the relevant 802.1p priority upstream. It is important though that the switches uplink port is tagged on that same VLAN, as 802.1p relies on 802.1Q tagged VLANs. For example, all ports are untagged in VLAN 1 by default, on your switch to switch links you would need to tag VLAN 1 on each end.

In my opinion though, it will be much better to configure a second VLAN for voice traffic and leave VLAN 1 completely untagged thoughout the network. If you decided that VLAN 2 would be the voice VLAN, you would simply tag all phone ports and switch to switch uplink ports, to be tagged in that VLAN. You would also configure the phones to be part of that VLAN as described in the pages above.

The PC's will continue to operate on VLAN 1 and will not affect the VoIP traffic.

With this method, you can force the voice VLAN priority as described in my other post. It looks as though you can also set this priority on the phone and the switch will honour this setting. I would force it on the switch just to be sure.

Don't forget to assign points to posts that have helped you.

Matt

[Andy Haigh_1]

Hi Matt,
Thanks for all that info, needed to look harder on Polycom's website.
Just in regards to setting up the VLAN id's, I take it I need to setup the VLAN's on all the switches on the LAN. With the VLAN I create for the phones I take it that should be set to tagged? In regards to the default VLAN should I just leave that as the default settings (untagged) or also make it tagged.

Thanks

Andy

[Matt Hobbs]

For the phone VLAN, you will tag it throughout the network, so the ports that are connecting the phones will be 'tagged'. You will also need to tag the uplink ports for this VLAN.

e.g. phones are on ports 1-10, and my uplink is port 26:

(config)#vlan 2
(vlan-2)#tagged 1-10,26
(config)#exit
(config)#wr mem

I would leave the default VLAN (1) as it is, untagged throughout. That way the PC's that are attached the phones will operate on VLAN 1 correctly.

[Andy Haigh_1]

Am I able just to tag all ports on the 2650 switches and only the uplinks in the 2824's?

The layout is the 2824's provide the backbone and a each NIC on the server is plugged into a seperate 2824, the NIC's are teamed. The Gig ports on the 2650's go to each 2824 and there is a link between the 2824's. The 2650-PWR's are to drive the phones and PC's and the 2824's provide the backbone.

How would the 2824's allow normal traffic to go via the default VLAN and the VOIP via it's and still have priority?? Lot's of questions, sorry.....

Thanks

Andy

[Matt Hobbs]

Hi Andy,

Yes you can do that. Tag your voice vlan for all ports on the 2650's, and on the 2824's tag only the ports that are going to the 2650's and the ports that connect the 2824's together.

As long as the voice VLAN remains tagged throughout the network, it will retain any 802.1p priority settings set by the 2650 edge switches.

Don't forget to assign points for each reply to your original posting.

Matt