[c-nsp] incoming queue

[Peter Rathlev]

On Wed, 2010-08-18 at 16:25 -0400, P.A wrote:
> Peter, I think I may of found the issue, looks like incoming queue
> based on DSCP trust will only work for some lan cards
> 
> "Congestion avoidance—If you configure an Ethernet LAN port to trust
> CoS or DSCP, QoS classifies the traffic on the basis of its Layer 2
> CoS value or its Layer 3 DSCP value and assigns it to an ingress queue
> to provide congestion avoidance. Layer 3 DSCP-based queue mapping is
> available only on WS-X6708-10GE ports."
> 
> I'm using, WS-X6548-RJ-45

You're right about that, you need "mls qos trust cos" on all ports on
the same ASIC. I tried to address that with:

> And 1) precludes you from using DSCP trust on other interfaces on the
> same ASIC. That may or may not be a problem for you.

If you absolutely need DSCP trust and cannot use either CoS trust or
move the DSCP-trust-needing ports to another ASIC, then it seems you
cannot alter the receive queues. :-|

You _might_ be able to simulate DSCP trust with an extensive input
service-policy, along the lines of:

 class-map DSCP0
  match ip dscp 0
 !
 class-map DSCP1
  match ip dscp 1
 !
 ...
 policy-map DSCP_TRUST
  class DSCP0
   set ip dscp 0
  !
  class DSCP1
   set ip dscp 1
  !
  ...
 !

It would look terribly clumsy though. And as you alluded to, CoS trust
only makes sense on trunk ports (they carry the 1p-bits) even though you
can configure access/routed interfaces to "trust cos".

-- 
Peter