Showing results for 
Search instead for 
Did you mean: 

Per-VLAN QoS on Nexus 5K


I was reading a QoS walkthrough earlier to try to solve my problem and I noticed that in IOS, you can specify "match vlan" in a class map.  This is not available in NX-OS. I'm not doing any routing on the 5K so I cannot match on ACL, and port where traffic is received is a trunk sharing other types of traffic I'd like to classify elsewise.

How can I match traffic on a per-VLAN basis?

5 Replies 5

Oleksandr Nesterov
Cisco Employee
Cisco Employee

Hi Matt.

Per-vlan qos will be available in next NX-OS release which will be posted in next quarter.



Okay, so if not VLAN, how about per-subnet? I have a dedicated subnet for my NFS traffic which I would like to get marked or placed into the Silver queue. Although I have an L3 daughter card installed, I'm not doing any routing on the N5K, so that said, let me know if the following is not possible.

Here's a partial config of what I'm trying to do. While per-VLAN QoS may not be possible, can I not use an access-list to match the appropriate subnet I'm expecting, refer to that access list in the "Silver_Traffic" class-map, then apply that class-map globally? And what exactly does that do? Surely it doesn't inspect the L3 header of each frame and match it against that ACL.

Sorry for the ambiguity, I'm still learning some of this stuff.

ip access-list MATCH_NFS_SUBNET

     permit ip any

class-map type qos class-fcoe

class-map type qos match-all Silver_Traffic

     match access-group name MATCH_NFS_SUBNET

policy-map type qos Global_Classify

  class Platinum_Traffic

    set qos-group 2

  class Silver_Traffic

    set qos-group 4

  class class-fcoe

    set qos-group 1

  class class-default

    set qos-group 0

system qos

  service-policy type qos input Global_Classify


config that you have posted does the following:

since it's aplied under "system qos" if checks traffic on all incomming interfaces and if traffic fails under conditions of certain class (ip range, cos, protocol etc...) it will be put in appropriate qos-group.

For example if traffic from range enters the switch - it will be marked with qos-group 4

Then you will need to create som further policies that will influence on outgong traffic maked with this group: bandwidth etc...

But before modifying qos read QoS config guide carefuly, because it can lead to many issues in the network.



Something like this? (This would be in addition to the config shown above)

class-map type network-qos Silver_Traffic_NQ

  match qos-group 4

policy-map type network-qos Setup_QOS

  class type network-qos Silver_Traffic_NQ

    set cos 4

    mtu 9000

system qos

  service-policy type network-qos Setup_QOS

That's interesting that it can still do L3 inspection on all switchports even though I'm not doing any routing of any kind on this switch - isn't that terribly inefficient?

Yes Matt, that's correct.

By adding this part of config you will change MTU for qous-group and set appropriate cos.



Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community:

Recognize Your Peers