[c-nsp] catalyst 6500 not rewriting CoS / 802.1p bits

[Vladimir Ivashchenko]

Hi Phil,

Thanks, your idea to mark as DSCP, and then rely on DSCP-COS translation
did the trick.

policy-map set-dscp-ef
  class class-default
   set dscp ef


On Sun, 2008-02-10 at 08:34 -0500, Phil Bedard wrote:
> If the port is marked as untrusted, the PFC still marks the packet
> with an internal DSCP value of 0 on ingress, so the "mls qos cos 5"
> command in this instance won't do what you want.   You can configure
> the "mls qos marking ignore port-trust" command, then the PFC will not
> rewrite the port cos value you set.  Another option is to use a
> policy-map to set certain traffic to trusted.  You could also set the
> ingress DSCP value with a policy-map and use the dscp-to-CoS map to
> set the correct egress cos.  The default map sets DSCP 40-46 to 5
> (divides by 8).   
> 
> 
> There may be another way as well that I'm missing.  I don't know that
> setting the port to trusted state will work, I believe for a trunk it
> will ignore the mls qos cos value.   
> 
> 
> Phil 
> 
> 
> 
> 
> On Feb 9, 2008, at 6:20 PM, Vladimir Ivashchenko wrote:
> 
> > Just to make sure I'm clear: "802.1p value for packets going out
> > from Gig2/1 is set to 0" - I mean packets received 
> > from Gig2/1, going to the Linux box on another interface, have CoS
> > bits set to 0, despite "mls qos cos 5" on the 
> > Gig2/1. The sniffer is running on the Linux box.
> > 
> > On Sun, Feb 10, 2008 at 12:31:37AM +0200, Vladimir Ivashchenko
> > wrote:
> > 
> > > Hi List,
> > > 
> > > We cannot get Cat6500 to rewrite CoS values (802.1p bits).
> > > 
> > > Configuration is 
> > > 
> > > mls qos
> > > no mls flow ip
> > > no mls flow ipv6
> > > no mls qos rewrite ip dscp
> > > no mls acl tcam share-global
> > > mls cef error action freeze
> > > 
> > > interface GigabitEthernet2/1
> > > switchport
> > > switchport trunk encapsulation dot1q
> > > switchport mode trunk
> > > no ip address
> > > load-interval 30
> > > wrr-queue queue-limit 40 30
> > > mls qos cos 5
> > > no cdp enable
> > > spanning-tree portfast trunk
> > > no mls qos trust
> > > 
> > > We have a sniffer connected to dot1q trunk on another port. The
> > > sniffer shows that 802.1p value for packets going out 
> > > from Gig2/1 is set to 0. We have tried searching Cisco site and
> > > playing with various commands, but did not succeed. IOS  
> > > 12.2(18)SXF5.
> > > 
> > > Catalyst 3560 has "mls qos cos override" command, which seems to
> > > do the trick, but this command is not available on 
> > > Catalyst 6500.
> > > 
> > > -- 
> > > Best Regards
> > > Vladimir Ivashchenko
> > > Chief Technology Officer
> > > PrimeTel, Cyprus - www.prime-tel.com
> > > _______________________________________________
> > > cisco-nsp mailing list  cisco-nsp at puck.nether.net
> > > https://puck.nether.net/mailman/listinfo/cisco-nsp
> > > archive at http://puck.nether.net/pipermail/cisco-nsp/
> > 
> > -- 
> > Best Regards
> > Vladimir Ivashchenko
> > Chief Technology Officer
> > PrimeTel, Cyprus - www.prime-tel.com
> > _______________________________________________
> > cisco-nsp mailing list  cisco-nsp at puck.nether.net
> > https://puck.nether.net/mailman/listinfo/cisco-nsp
> > archive at http://puck.nether.net/pipermail/cisco-nsp/
> 
-- 
Best Regards,
Vladimir Ivashchenko
Chief Technology Officer
PrimeTel PLC, Cyprus - www.prime-tel.com