is QoS preserved when links are placed in a port channel?

aoshea · ‎11-22-2004

Dear support, many thanks for the support I have received already on this matter, but have one small question I need to answer.

I have recently implemented QoS between two 3550-48 EMI switches. All appears fine on the switches (i.e. traffic is showing as being clasified).

In order to prepare myself for a possible bun-fight with Avaya, I need to know that traffic is still maintaining its classification and priority queue when placed in a port channel ? (DSCP 46 is being used for VoIP traffic).

The two sites are link by 2 x 100Mbps lasers, which are logically bound into 'port channel 1'. An extract from one of the 3550-48s is attached, the configuration is the same on the other site.

Thank you again in advance for your assistance.

Regards, Adrian.

pflunkert · ‎11-23-2004

Hi,

i don't verify you configuration exactly, but it looks okay. With QoS, your configuration is taken on the physical port. The channel is only a logical link. But you must be sure that on both physical links the qos config is the same. Then all will works.

Regards

Peter

aoshea · ‎11-29-2004

Hi Peter,

Thanks for you helps, still a little confused, or I might be misreading it, but if I issue the following command at either of the switches it does not mention QoS is enabled on the port channel;

coreswitchg#sh auto qos int por1

AutoQoS is disabled

coreswitche#sh auto qos int por1

Port-channel1

AutoQoS is disabled

Does this effect QoS on the port channel ?

The ports are showing correct information; (port 46&48 are in port channel 1, and 47 is the avaya phone switch (uses dscp 46 for IP telephony)).

coreswitchg#sh mls qos int fas0/46

FastEthernet0/46

trust state: trust cos

trust mode: trust cos

COS override: dis

default COS: 0

DSCP Mutation Map: Default DSCP Mutation Map

trust device: none

coreswitchg#sh mls qos int fas0/47

FastEthernet0/47

trust state: trust cos

trust mode: trust cos

COS override: dis

default COS: 0

DSCP Mutation Map: Default DSCP Mutation Map

trust device: none

coreswitchg#sh mls qos int fas0/48

FastEthernet0/48

trust state: trust cos

trust mode: trust cos

COS override: dis

default COS: 0

DSCP Mutation Map: Default DSCP Mutation Map

trust device: none

coreswitchg#sh mls qos ?

aggregate-policer Show aggregate-policer information

interface Show interface information

maps Show mapping information

| Output modifiers

coreswitchg#sh mls qos

QoS is enabled

coreswitchg#sh mls qos ma

Policed-dscp map:

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

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

0 : 00 01 02 03 04 05 06 07 08 09

1 : 10 11 12 13 14 15 16 17 18 19

2 : 20 21 22 23 24 25 26 27 28 29

3 : 30 31 32 33 34 35 36 37 38 39

4 : 40 41 42 43 44 45 46 47 48 49

5 : 50 51 52 53 54 55 56 57 58 59

6 : 60 61 62 63

Dscp-cos map:

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

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

0 : 00 00 00 00 00 00 00 00 01 01

1 : 01 01 01 01 01 01 02 02 02 02

2 : 02 02 02 02 03 03 03 03 03 03

3 : 03 03 04 04 04 04 04 04 04 04

4 : 05 05 05 05 05 05 05 05 06 06

5 : 06 06 06 06 06 06 07 07 07 07

6 : 07 07 07 07

Dscp-switch priority map:

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

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

0 : 00 00 00 00 00 00 00 00 00 00

1 : 00 00 00 00 00 00 01 01 01 01

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

3 : 01 01 02 02 02 02 02 02 02 02

4 : 02 02 02 02 02 02 02 02 03 03

5 : 03 03 03 03 03 03 03 03 03 03

6 : 03 03 03 03

Cos-dscp map:

cos: 0 1 2 3 4 5 6 7

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

dscp: 0 8 16 26 32 46 48 56

IpPrecedence-dscp map:

ipprec: 0 1 2 3 4 5 6 7

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

dscp: 0 8 16 24 32 40 48 56

Dscp-dscp mutation map:

Default DSCP Mutation Map:

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

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

0 : 00 01 02 03 04 05 06 07 08 09

1 : 10 11 12 13 14 15 16 17 18 19

2 : 20 21 22 23 24 25 26 27 28 29

3 : 30 31 32 33 34 35 36 37 38 39

4 : 40 41 42 43 44 45 46 47 48 49

5 : 50 51 52 53 54 55 56 57 58 59

6 : 60 61 62 63

coreswitchg#

Once again your help is appreciated.

Regards,

Adrian.

pflunkert · ‎11-29-2004

Hi Adrian,

You can use the auto-QoS feature to simplify the deployment of existing QoS features. Auto-QoS makes assumptions about the network design, and as a result, the switch can prioritize different traffic flows and appropriately use the egress queues instead of using the default QoS behavior. When Auto-QoS is not used it don't mean that you can't use the "normal" QoS ar that is not enabled.

Your configuration is okay.

Regards

Peter