How do i mark packets with dscp values on cat3560emi?

[Istvan kelemen]

Hi,

The topology is the following:

PC ------ fa0/1 ---- c3560 ----- interface vlan10 (10.10.10.10)

I would like to mark ICMP packets with dscp 46 so i placed a policy map on interface f0/1 inbound.

The switch doesn't mark the packets. I have tried several configuration, no success at all.

WS-C3560-24PS      12.2(55)SE8           C3560-IPSERVICESK9-M

Can anyone help me out pls?

[Sandeep Choudhary]

HI Istvan,

There are two cases

1- Does your PC sending marked frame. If so just inform your interface to trust dscp value

  mls qos trust dscp

   you can verify this via.

   show mls qos interface

   output should be "trust state: trust dscp"

2- If your pc is not marking and you want to mark it on incoming interface just issue below command

  policy-map PC

  class class-default

  set ip dscp

int

  service-policy input PC

Hope It helps.

Regards

[Istvan kelemen]

Thank you for your post.

policy-map PC

class class-default

  set ip dscp ef

interface FastEthernet0/10

switchport access vlan 10

switchport mode access

no mdix auto

service-policy input PC

Switch#show policy-map interface fastEthernet 0/10

FastEthernet0/10

  Service-policy input: PC

    Class-map: class-default (match-any)

      0 packets, 0 bytes

      5 minute offered rate 0 bps, drop rate 0 bps

      Match: any

        0 packets, 0 bytes

        5 minute rate 0 bps

That's the problem.

[Sandeep Choudhary]

HI please check this command:

is this port is in working mode means....no input and output packets shown in output.

Configure this command on your interface fa0/10:  mls qos cos 3

Regards

[Istvan kelemen]

hi,

i used wireshark to look deeper into the packets, they are getting marked, however the switch doesn't show

[sgouldbo]

Hi Istvan,

The behavior that you are seeing is expected, since fixed unit switches do not display the QoS statistics when using the "show policy-map interface gix/x" command.

On fixed units we can use the "show mls qos interface gix/x statistics" to verify the marking of packets on ingress/egress.  Or verify the markings with a sniffer capture as you did.

show policy-map [policy-map-name [class class-map-name]]

Display QoS policy maps, which define classification criteria for incoming traffic. Note Do not use the show policy-map interface privileged EXEC command to display classification information for incoming traffic. The control-plane and interface keywords are not supported, and the statistics shown in the display should be ignored.

http://www.cisco.com/en/US/docs/switches/lan/catalyst3560/software/release/12.2_55_se/configuration/guide/swqos.html#wp1021811

Hope this information was helpful.