Priority queue on ME3400

[Iulian Vaideanu]

I'm trying to deploy a simple traffic prioritization on a ME3400G-2CS running metroipaccessk9-mz.122-55.SE11 and I'm not sure whether I'm being successful or not.  Under interface Gi0/3 I have "service-policy output out-policy-dtv", where

class-map match-any out-class-dtv
 match cos  4
!
!
policy-map out-policy-dtv
 class out-class-dtv
    priority

"show platform qos debug interface queueing" says

GigabitEthernet0/3
Egress Priority Queue : enabled
Shaped queue weights (absolute) :  0 0 0 0
Shared queue weights  :  1 255 255 4
The port bandwidth limit : 100  (Operational Bandwidth:100.0)
The port is mapped to qset : 4

But a while after "clear counters", "show platform qos statistics interface gigabitEthernet 0/3" shows a lot of "cos: outgoing" packets for CoS 4, while "show policy-map interface gigabitEthernet 0/3" shows zero packets for "Class-map: out-class-dtv".  So, is that class-map matched against or not?

  cos: outgoing
-------------------------------

  0 -  4 :      184026            0            0            0      1921699
  5 -  7 :           0            2            1

 GigabitEthernet0/3

  Service-policy output: out-policy-dtv

    Class-map: out-class-dtv (match-any)
      0 packets
      Match: cos  4
        Priority
      Output Queue:
        Max queue-limit default threshold: 160
        Tail Packets Drop: 0

    Class-map: class-default (match-any)
      4203766 packets
      Match: any
        Output Queue:
          Max queue-limit default threshold: 160
          Tail Packets Drop: 405

[Hitesh Vinzoda]

Hi dude,

Lets first check the dependencies, as per the config guide. Is your port a dot1q trunk?

Classification Based on Layer 2 CoS

You can use the match command to classify Layer 2 traffic based on the CoS value, which ranges from 0 to 7.

---

Note A match cos command is supported only on Layer 2 802.1Q trunk ports.

---

This example shows how to create a class map to match a CoS value of 5:

Switch(config)# class-map premium

Switch(config-cmap)# match cos 5

Switch(config-cmap)# exit

[Iulian Vaideanu]

Yes, the port has

 port-type nni
 switchport trunk allowed vlan 110,111,994
 switchport mode trunk

[Iulian Vaideanu]

I read this in the config guide: "An output policy map attached to an egress port can match only the packets that have already been matched by an input policy map attached to the ingress port for the packets."

So I created the maps below, which I applied (on input) on the interface the traffic of interest comes in.  Now I have matches of out-policy-dtv on Gi0/3, but I have no matches (not even for class-default) of in-policy-dtv on the other interface :)...

class-map match-any in-class-dtv
 match cos  4

policy-map in-policy-dtv
 class in-class-dtv
  set cos 4