[c-nsp] MPLS EXP label imposition

[Oliver Boehmer (oboehmer)]

Merlin Gillespie <> wrote on Thursday, September 08, 2005 4:09 PM:

> Following reading:
> http://www.cisco.com/warp/public/cc/pd/iosw/tech/mpotc_qp.htm
> 
> The following passage was brought to my attention:
> 
> By default, Cisco IOS(r) Software copies the three most significant
bits
> of the DiffServ code point (DSCP) or the IP precedence of the IP
> packet to the EXP field in the MPLS shim header.
> 
> There is not much reference to this feature outside of the prior
> mentioned document.
> Can someone confirm that this is the default behaviour.

Yes, it is (I figure it is in most MPLS devices).

> If it is the default behaviour whether there is a global configuration
> to prevent this from happening.
> Or, if the only way to prevent this from happening is to manually
> rewrite all precedence bits to 0.

You can use the "MPLS DiffServ Tunneling Modes" feature
(http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newf
t/122t/122t13/ftdtmode.htm) and overwrite this with an appropriate
policy-map with "set mpls experimental 0" applied on the ingress
interface..

	oli