VoIP Qos with 3550 and 3560's

[somanabich]

I have several 3560's and 3550's and I am wanting to configure QoS for VoIP traffic.

My VoIP phones are Alcatel and use DSCP 46 for voice bearer traffic.

As I understand th 3550's by default put DSCP 46 traffic into queue 3, so I need to use wrr-queue command to change this so that DSCP46( COS 5) is put into queue 4, the expedite queue. Is that correct?

Also, by default when QoS is enabled on the 3560, DSCP=46 (COS 5) is put into queue 1 (expedite queue). Again is this correct?

Also has anyone got any experience with Alcatel phones on Cisco switches?

What command can be used to verify that DSCP 46 traffic is being out into the expedite queue?

Regards

Nik Mihelioudakis

[spremkumar]

hi

i would suggest to change the dscp-cos map for the dscp value 46.so that it can match cos value 6 ..

try this command in ur switch and check out the dscp-cos maps and also the wrr queue maps.

mls qos map dscp-cos 46 to 6

As default 48 gets in place of cos 6 by this command you replace 48 and placing 46 out there.

do revert whether it works out for you.

Also make your switch port to trust the incoming DSCP values so that it will not mark with the default dscp values.

regds

[bill.efthimiou]

Hello Nik,

Use command:

"sh mls qos interface gigabitEthernet 0/1 queueing" to work out how DCSP/COS is queued. For example;

emu0s2#sh mls qos interface gigabitEthernet 0/1 queueing

GigabitEthernet0/1

Egress expedite queue: ena

wrr bandwidth weights:

qid-weights

1 - 25

2 - 25

3 - 25

4 - 25 when expedite queue is disabled

Dscp-threshold map:

d1 : d2 0 1 2 3 4 5 6 7 8 9

---------------------------------------

0 : 01 01 01 01 01 01 01 01 01 01

1 : 01 01 01 01 01 01 01 01 01 01

2 : 01 01 01 01 01 01 01 01 01 01

3 : 01 01 01 01 01 01 01 01 01 01

4 : 01 01 01 01 01 01 01 01 01 01

5 : 01 01 01 01 01 01 01 01 01 01

6 : 01 01 01 01

Cos-queue map:

cos-qid

0 - 1

1 - 1

2 - 2

3 - 2

4 - 3

5 - 4

6 - 3

7 - 3

In this case COS of 5 (DSCP 40 o 46) is queued to queue 4, which is the priority queue. If not, to change use command:

"wrr-queue cos-map 4 5"

You are also correct about the 3560. DSCP 46 (COS 5) by default goes to queue 1, the priority queue. To verify:

sh mls qos maps dscp-output-q

To change try the following command:

mls qos srr-queue output dscp-map queue 1 threshold 3 46

If all else fails, I suggest you read the following documents:

3550 QOS config guide:

http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12120ea2/index.htm

3560 QOS config guide:

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3560/12225se/index.htm

Enterprise Quality of Service SRND:

http://www.cisco.com/warp/public/779/largeent/it/ese/srnd.html

I hope this helps.

Yiasou

Bill Efthimiou

[somanabich]

Yiasou Bill

When I run 'sh mls qos int fa0/11 que' on my 3550 I get

FastEthernet0/11

Egress expedite queue: ena

wrr bandwidth weights:

qid-weights

1 - 25

2 - 25

3 - 25

4 - 25 when expedite queue is disabled

Cos-queue map:

cos-qid

0 - 1

1 - 1

2 - 2

3 - 2

4 - 3

5 - 3

6 - 4

7 - 4

So I gues I need to run ' wrr-queue cos-map 4 5'?

And when I run 'sh mls qos int gi0/4 q' on my 3560 I get

GigabitEthernet0/4

QoS is disabled. When QoS is enabled, following settings will be applied

Egress Priority Queue : disabled

Shaped queue weights (absolute) : 25 0 0 0

Shared queue weights : 25 25 25 25

The port bandwidth limit : 100

The port is mapped to qset : 1

c3560_floor1_1#sh mls qos maps dscp-output-q

Dscp-outputq-threshold map:

d1 :d2 0 1 2 3 4 5 6 7 8 9

------------------------------------------------------------

0 : 02-01 02-01 02-01 02-01 02-01 02-01 02-01 02-01 02-01 02-01

1 : 02-01 02-01 02-01 02-01 02-01 02-01 03-01 03-01 03-01 03-01

2 : 03-01 03-01 03-01 03-01 03-01 03-01 03-01 03-01 03-01 03-01

3 : 03-01 03-01 04-01 04-01 04-01 04-01 04-01 04-01 04-01 04-01

4 : 01-01 01-01 01-01 01-01 01-01 01-01 01-01 01-01 04-01 04-01

5 : 04-01 04-01 04-01 04-01 04-01 04-01 04-01 04-01 04-01 04-01

6 : 04-01 04-01 04-01 04-01

So I gues that DSCP 46 is being put into the correct queue (queue 1 - priority queue)

Eyxaristo

Nik