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New Member

Copy customer COS value from to outer SP tag

I have come across documents on Metro switches which mention that customer assigned COS values can be mapped to the outer metro tag. This is a useful feature to ensure cust applications receive appropriate level of treatment across the SP backbone.

I haven't come across any configuration guide on this subject. Would appreciate any kind of help on this matter.

Thanks in advance,


New Member

Re: Copy customer COS value from to outer SP tag

You don't need a config to make this working.

Just setup the port as trusted and the outer tag will be equal the inner tag.

Re: Copy customer COS value from to outer SP tag

Most of the Cisco switches have multiple trust states based on the requirement.

Whether to trust DSCP which is the default or Prec or COS as per the need.

Now for copying the received COS value to the outer TAG you can enable the DOT1Q Tunnel Interface to a Trust COS state where by it will copy the inner COS value to the Outer VLAN TCI field.

Here is a link which explain the Port Classification. Here you can look up the "Configuring port trust states"

The interface command "mls qos trust cos" classifies an ingress packet by using the packet CoS value. For an untagged packet, the port default CoS value is used.

The default port CoS value is 0.

For 802.1Q tunnels, the switch copies the inner CoS value to the outer CoS value and sends the packet out.



New Member

Re: Copy customer COS value from to outer SP tag

Thanks Swaroop, Tiago. Your inputs have been of help.

Is this feature restricted to ME switches or available with all switches, say 6509E or 3750 (non Metro E)?

Thanks in advance,