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mpls qos

Hi All,

I have setup is as below.

L2 switch ingresss qinq connecting to customer ----------------------- L2 switches ------------------------- L3 switch with MPLS (xconnect ingress for customer circuit)------------ L3 switches with MPLS ----------------------------- L3 switch with MPLS (xconnect egress for customer circuit) ---------------- L2 switches --------------- L2 switch egress qinq connecting to customer

edge switches are me-3400 and input policers configured to set COS value to 2. L3 switches are 7609 with 6704 1G card connecting to layer 2 switches and ES20 10G card connecting to MPLS core.

I am giving 'mls qos trust cos' on 1G ports towards L2 and 'mls qos trust dscp' on 10G ports towards MPLS core. On xconnect interfaces I am attaching policy with 'set mpls experimental 2'

I am trying to understand packet QoS life across this setup:

At ingress PE I gave 'mls qos trust cos', so 7609 generates initial internal DSCP from COS (here cos=2), later going through policy-maps it will set EXP=2 in outer label when handing packet to next LSR.

Next LSR handles packet with outer label EXP.  My question is how PHP LSR handles this packet in egress when outer label got removed. Does it copy outer label EXP to inner label or it looks packet IP Precedence values?

Next question, at egress PE in ingress (packet coming from MPLS core) packet has only inner label. How initial internal DSCP is generated for this packet?--------------------- based on the final internal DSCP packet COS value will be derived before handing packe to L2 switches connected to 6704 LAN ports.

comments from qos experts are appreciated.


Siva Kondala Rao

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