mls qos trust cos and other conf in trunk link

ahurtadove · ‎09-23-2010

Hi all, I have a friend who has this config on an interface in a 6500 SW:

interface GigabitEthernet4/1
description XXXXXXXX
switchport
switchport trunk encapsulation dot1q
switchport mode trunk
no ip address
wrr-queue bandwidth 5 25 70
wrr-queue queue-limit 5 25 40
wrr-queue random-detect min-threshold 1 70 100 100 100 100 100 100 100
wrr-queue random-detect min-threshold 2 70 100 100 100 100 100 100 100
wrr-queue random-detect min-threshold 3 50 60 70 80 90 100 100 100
wrr-queue random-detect max-threshold 1 100 100 100 100 100 100 100 100
wrr-queue random-detect max-threshold 2 100 100 100 100 100 100 100 100
wrr-queue random-detect max-threshold 3 60 70 80 90 100 100 100 100
wrr-queue cos-map 1 1 1
wrr-queue cos-map 2 1 0
wrr-queue cos-map 3 1 4
wrr-queue cos-map 3 2 2
wrr-queue cos-map 3 3 3
wrr-queue cos-map 3 4 6
wrr-queue cos-map 3 5 7
mls qos trust cos

I believe this config was made with an auto qos command that was deleted but the rest is still there like de wrr commands and also believe that this does not make any improvement in this link so those are not doing anything in there and can be deleted.

The thing is that I don't have the technical explanation to convince him that this is not a way to configure a trunk link.

Would you help me with this?

Thank you in advance

jonathanaxford · ‎09-23-2010

Hi Antonio,

All of the commands are indeed related to QoS - if there is not reason for QoS to be running on that link then they can all be removed and the trunk will still function as normal. I haven't used autoqos on a Cat6500, but it looks very similar to the Qos configs i have on a 6500 here that was manually configured.

If you are running things like IP telephony over the trunk and want to ensure that the voice traffic is prioritised, then it is a good idea to have QoS configured. If you are not, and you want all traffi cto receive equal treatment, then remove all of the following commands:

wrr-queue bandwidth 5 25 70
wrr-queue queue-limit 5 25 40
wrr-queue random-detect min-threshold 1 70 100 100 100 100 100 100 100
wrr-queue random-detect min-threshold 2 70 100 100 100 100 100 100 100
wrr-queue random-detect min-threshold 3 50 60 70 80 90 100 100 100
wrr-queue random-detect max-threshold 1 100 100 100 100 100 100 100 100
wrr-queue random-detect max-threshold 2 100 100 100 100 100 100 100 100
wrr-queue random-detect max-threshold 3 60 70 80 90 100 100 100 100
wrr-queue cos-map 1 1 1
wrr-queue cos-map 2 1 0
wrr-queue cos-map 3 1 4
wrr-queue cos-map 3 2 2
wrr-queue cos-map 3 3 3
wrr-queue cos-map 3 4 6
wrr-queue cos-map 3 5 7
mls qos trust cos

Hope this helps,

Jonathan

ahurtadove · ‎09-23-2010

Hello Jonathan, there are phone services working on that link indeed, they are siemens phones.

The thing is that, being gigabit ports I guess that qos is not something to really care for because they only have host computers and not servers with giga ports.

Now, in the case that they would like to mantain them I guess the command should be configured in both sides of the trunk (it is only configured in one end), is that right?

Thank you very much.

francisco_1 · ‎09-23-2010

do you know what card this is? can you post "show module"

Francisco.

ahurtadove · ‎09-23-2010

Hello francisco, I cannot access these devices right now so it would be difficult for me to post this.

Thank you