[c-nsp] Sup720 & Sup32 ingress TOS/EXP marking

[Önder Ergün (Probil-İstanbul)]

You can only set the mpls exp bit of an mpls packet not the precedence field of the ip header. 

I am not sure about Sup32 but Sup720 has strange behaviours with MPLS QoS which are documented also. 

>From http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/122sx/swcg/mplsqos.htm

"During IP-to-MPLS imposition, IP ToS marking is not supported. If you configure a policy to mark IP ToS, the PFC3BXL or PFC3B marks the EXP value. "

So, in your test bed you can mark the ip precedence of packets on 7401 PE-CE interface, or mark the MPLS EXP bit on Sup32 but if you want to preserve the ToS byte you should use another policy on the PHP router(7200) to copy the EXP bit to precedence.


Onder


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Ran Liebermann
Sent: Sunday, January 15, 2006 10:53 AM
To: Asbjorn Hojmark - Lists
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Sup720 & Sup32 ingress TOS/EXP marking

Hi,

The topology of the test with the Sup32 is as following:

Device type: Laptop1     7401       Sup32         7200       7200      Laptop2
P/PE/CE    : ( CE ) --- ( PE ) --- (  P  ) ----  ( P ) ---- ( PE ) --- ( CE )
Interface #:            1    2     3     4       5   6      7    8

In the test we try to ping from Laptop2 to Laptop1, setting the packets with TOS=0x00.  The policy in question is deployed on interface #4 (on the Sup32).

The configuration of the Sup32 is the following:
-------------------- [Start Quote] -------------------- no mls flow ip no mls flow ipv6 mls qos no mls acl tcam share-global mls cef error action freeze !
class-map match-all TEST
  match mpls experimental topmost 0
!
policy-map TEST
  class TEST
   set precedence 3
!
interface GigabitEthernet5/8     ! i.e Interface #3 - Output interface
 ip address x.x.31.129 255.255.255.252
 ip router isis
 speed nonegotiate
 tag-switching ip
!
interface GigabitEthernet5/9     ! i.e. Interface #4 - Input interface
 ip address x.x.31.2 255.255.255.128
 ip router isis
 mpls label protocol ldp
 tag-switching ip
 clns mtu 1000
 service-policy input TEST
-------------------- [ End Quote ] --------------------

Show mpls forwarding-table command to the destination laptop from the 7200 P router:

-------------------- [Start Quote] -------------------- 7200-P#show mpls forwarding-table x.x.31.134
Local  Outgoing    Prefix            Bytes tag  Outgoing   Next Hop
tag    tag or VC   or Tunnel Id      switched   interface
199    16          x.x.31.132/30     97787460   Gi0/1.24   x.x.31.2
7200-P#
-------------------- [ End Quote ] --------------------

And the same command from the Sup32:

-------------------- [Start Quote] -------------------- SUP32#show mpl for x.x.31.134
Local  Outgoing    Prefix              Bytes tag  Outgoing   Next Hop
tag    tag or VC   or Tunnel Id        switched   interface
16     Pop tag     x.x.31.132/30       93575410   Gi5/8      x.x.31.130
SUP32#
-------------------- [ End Quote ] --------------------

And the packets are received with TOS=0x00 in Laptop1.

Thanks!
--
Ran.


On 14/01/06, Asbjorn Hojmark - Lists <Lists at hojmark.org> wrote:
> > We've been trying to do TOS marking with both a Sup720-3BXL and a 
> > Sup32 at the ingress, but with no success.
>
> A little bit of config would be helpful...
>
> Are you trying to do that with trust? That's not supported on 1q4t 
> ports (except GE) like those on the 6348.
>
> How are you trying to mark the traffic? With 'set ip prec' in a policy 
> map for a service-policy on the ingress interface?
>
> -A
>
>

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