[c-nsp] Rewritting DSCP values on input - Bug? Not supported? User Error?

[Tóth András]

Hi Brad,

Try removing the mls qos trust dscp from the inbound port.

"For traffic from trust DSCP ports, PFC QoS uses the received DSCP
value as the initial internal DSCP value. PFC QoS does not mark any
traffic on ingress ports configured to trust received DSCP."
http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/qos.html#wp1704338

Best regards,
Andras


On Fri, May 27, 2011 at 7:26 PM, Brad Roldan <broldan at gmail.com> wrote:
> Here's my setup:
>
> Test PC1 -----7609----Test PC2
>
> The 7609 is running a variant of 12.2(33)SR. And the line card I am trying
> to do this on is a WS-X6724-SFP. There are actually other routers in the
> setup, but for the sake of simplicity, we only need to loop at the above
> topology.
>
> The task:
> Rewrite DSCP on packets received from Test PC2 from CS3 (Class Selector 3)
> to CS2 (Class Selector 2).
>
> Here is the configuration I'm using:
> ! First create a class map to identify packets of interest
> class-map match-all Priority
>  match ip dscp cs2 cs3 cs4
> !
> ! Now define service policy that will do the re-writing
> policy-map Priority-Rewrite
> class Priority
>  set dscp cs2
> !
> ! Now I apply this to an interface (inbound)
> interface GigabitEthernet1/1
>  description Aggregation Port
>  no ip address
>  speed nonegotiate
>  mls qos trust dscp
> !
> interface GigabitEthernet1/1.25
>  description Test PC 2
>  encapsulation dot1Q 25
>  ip address 10.154.0.2 255.255.255.252
>  service-policy input Priority-Rewrite
> !
>
> When I send traffic marked with CS3 (0x60) through the router from Test PC2,
> I noticed that the value is preserved all the way to Test PC1. What really
> has me scratching my head is that when I reverse the logic and set the
> service-policy as outbound, traffic from Test PC1 marked with 0x60 is
> properly remarked to 0x40.
>
> I'm hoping that I am just doing this wrong, and that it is possible to
> re-write the DSCP tag on inbound.
>
> I've tried using dscp-mutation, but that does not seem to work for inbound
> traffic either.
>
> Thanks,
>
> Brad
>
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