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QoS on sup720

Hi,

I have a strange QoS problem with one Cisco7600 (sup7203BXL, IOS 12.2(33)SRE6).

This is layer 2 traffic,and all ports are L2 dot1q trunks:

1) Packet comes with DSCP 46 on Gigabit port (WS6728-SFP) with "mls qos trust dscp" configured. It goes out the port of the same card/slot with DSCP 0.

2) packet comes with DSCP 46 on different Gigabit port on the same card/slot with "mls qos trust dscp" and also "mls qos vlan-based" configured. It qoes out out the port with DSCP 46.

Why the switch behave differently if "mls qos vlan-based" is configured on port (or to say it works correct since it doesn't override DSCP)?

I have global command "mls qos rewrite ip dscp" since this 7600 is also MPLS PE router and I found in documentation that "mls qos rewite ip dscp" is mandatory for QoS on MPLS (EXP bits). So I can't turn off "rewrite ip dscp". Again the problem that I presents is L2 problem not MPLS (MPLS is used for different traffic).

Also mls qos mappings are ok COS to DSCp are 5 to 46 and vice versa.

Furthermore, as far as I know if I have configured "mls qos trust dscp" on Gigabit ethernet port, switch (7600) should work in this order:

- make internal DSCP from packet DSCP

- since I don't have configured DSCP mutation DSCP should stay the same (46)

- using map DSCP - COS ( 46 -5 ) switch will choose queue on outgoing interface in regards to mapped COS

Is this correct or am I missing something?

please help.

regards,

A

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