how to trust DSCP

[bindong.shi]

hi all,

My question is how to use the command "mls qos marking ignore port-trust": does that mean we can use this command to not to change any packet's DSCP value, when the packet passing through the switch?

I know there is another way to not changing packet's DSCP value, we also configure "mls qos trust dscp", but tis is under inteface level command, which means we have to implement the command on all the interfaces, which need to leave the DSCP untouched. In a big Data center-- comprising of access switch, distribution switch and core switch, we need to put this command every where.

So my question again, is there a command can help us to not changing DSCP value, and can be configured on the switch globally, instead of interface level?

thanks

[Reza Sharifi]

Hi,

DSCP is globally enabled by default:

Command Default

The defaults are as follows:

•If you enable global QoS, the port is not trusted.

•If no keyword is specified or the global QoS is disabled, the default is dscp.

http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_m2.html#wp1044294

HTH

Reza

[Jon Marshall]

You don't say which switches you are talking about but you should be able to use -

switch(config)# no mls qos ip rewrite dscp

6500  command reference

this will mean the DSCP value is not changed as it passes through the switch.

Jon