Mitel 3300... to tag, or not to tag... that is the question! 3

[cepacs]

I have a Mitel 3300 and it's tagged and I'm using priority 6. My switch recognizes the priority that the 3300 has given the voice traffic and this is how QoS is handled.

My question is, do I need tagging setup on the switch port connected to the Mitel? Only the Mitel will be connected to this port, but since the Mitel is the one setting the priority, I'm thinking maybe tagging needs to be allowed? Or does the priority come from the phone? I noticed when the IP phone boots up, it shows the priority set to 6 (which it got from the 3300).

 

[kwbMitel]

Typically you would have the following with few exceptions.

Data only device ports
- Untagged on Data VLAN
- No Access on Voice VLAN

Phone and Data Ports
- Untagged on Data VLAN
- Tagged on Voice VLAN

Voice Only ports (Controllers and Applications Servers)
- Untagged on Voice VLAN
- No Access on Data VLAN

**********************************************
What's most important is that you realise ... There is no spoon.

 

[bobcheese]

Agree with kwbMitel 100%. IME tagging on the controller causes more problems than it fixes. Best left to the switches.

 

[cepacs]

The only thing is, if I setup tagging on the 3300, then I can have it set the priority. Our 3Com switch automatically queues it correctly according to the priority passed to the phone by the 3300.

I could set it up priority on the switch, but I'd have to create an ACL, link it to a Classifier, then create a Behavior, and finally use those to create a QoS policy. 3Com does not make it easy! We have an HP 8212zl and that is much more straight forward.

 

[LoopyLou]

We talking layer 2 or 3 priority?



The single biggest problem with communications is the illusion that it has taken place.

 

[cepacs]

I believe layer 2... the 802.1p priority.

 

[LoopyLou]

If you set the 3300 to tagging you also can supply priority. The phones get their VLAN and priority during boot. It comes either form LLDP or DHCP.

The single biggest problem with communications is the illusion that it has taken place.

 

[Mitelmatt]

Tagging has nothing to do with priority, Tagging tells you which VLAN to go on and allow Tagged packets.

The 3300 default sends all packets with Priority 6 and the phones sends back with 6 (default)

You can change both in QOS form for the 3300 side and dhcp for phone side.

Depending on what type of switches you have depends on what QOS you need. i.e. Cisco and Auto QOS uses COS 5 for the EF mapping queue whereas i believe HP uses 6. Not sure about 3com

But say in a cisco environment you only need to set the Priority on that port if you want to change it. If not you don;t need it. The 3 coms should have some queueing and the COS / dscp is mapped to queues, ie. cos 5 or 6 will be in a higher priority queue etc.

In most SMB cases if you're using VLAN's then that's enough QOS. Sometimes you can over QOS when not needing too

Does that make sense?

 

[cepacs]

Tagging has nothing to do with priority? Well that seems to go against what I have been told and what I have read.

"There is no 802.1P without 802.1Q VLAN tagging. The VLAN tag carries VLAN information—the VLAN ID (12 bits) and prioritization (3 bits)."

http://fengnet.com/book/ICUNA/ch13lev1sec5.html

Priority is carried in the VLAN tag. This is the reason to use things like DiffServ, so you don't have to rely on vlan tagging.

http://www.hp.com/rnd/device_help/h...J8992A/conf/qualityofservice/qosdiffserve.htm

Quote from Mitelmatt:
"In most SMB cases if you're using VLAN's then that's enough QOS. Sometimes you can over QOS when not needing too. Does that make sense?"

That makes absolutely no sense to me! Just setting up VLANs will not give you QoS when you are talking about VoIP. I just recently heard a story from our Mitel rep about one of his customer complaining of calls being dropped and calls getting choppy and they found out it was due to an employee uploading ISO files to a server. Of course it was mostly due to lack of QoS, but it shows you that one person can bring down your VoIP if you are not doing QoS properly.

 

[Mitelmatt]

Sorry i think you're mis understanding,

Tagging a port basically means allow packets tagged for VLAN, basically telling the network it belongs on VLANX. Yes the prioity gets sent too, but what i was trying to say is it is sent from the 3300 and phones, you don;t need to set it on the switch (or at least in HP and Cisco) as the tables with priority already exist. Yes you can set the prioity on switches but that is for if the servers etc don;t give out the prioity, you can use it also to change it.

But in a 3300 environment the RTP is sent with P6 and signalling P3 i think.

YOu then tell the phones via DHCP how to send it back.

So on a switch you just set up VLANs and place the PC's and phones in the VLAN and any RTP gets sent with p6 and signalling p3. The tables in the switches then know how to handle the priority and queue accordingly.

Data by default has p0.

But the meaning "Tagging" is more to do with allow Tagged packets.

So in my comment about just setting up VLANs, then yes it is that easy. On a LAN at 100mb with VLANS and letting the 3300 and phones just send the priority is more than enough qos in most circumstances.

Yes if you have remote phones over low links more qos etc may be applied at layer 3 etc.

Does that make more sense?

 

[actswitch]

I remember when telephony was climbing a pole and running a dropwire.......happy days!

 

[CharlesBr]

Mitelmatt, I would add that in some switches you would want to "trust" the cos set by the phones and the controller, otherwise they'll reset the diffserv and layer 2 tags back to the default priority queue.

 

[Mitelmatt]

yes charlesbr i agree!