[c-nsp] Mapping Between IP Precedence and MPLS EXP

[Oliver Boehmer (oboehmer)]

Hmm, interesting.. I felt common practice (and inline with the DiffServ
model) is to enforce the trustable boundary on all links anyway, so a
default "set ip dscp 0" for non-premium customers is part of a default
interface config? 
But I also see your point: You're relying on all traffic being
MPLS-switched within your core, so you could save this work and just
enable TOS reflection on a per-interface basis. 

	oli

David Freedman <> wrote on Tuesday, April 10, 2007 4:26 PM:

> <rant>
> 
> Yes, I'm amongst the bunch who find auto TOS reflection extremely
> annoying and would like a switch to turn it off.
> 
> With TOS reflection if you are providing a premium service to people
> who you allow to do their own TOS marking you need to re-mark all
> traffic on ingress from customers rather than being able to turn off
> the reflection and reflect TOS->EXP manually for customers thay pay
> for the service. 
> 
> </rant>
> 
> Dave.
> 
> Oliver Boehmer (oboehmer) wrote:
>> Alaerte Vidali <> wrote on Tuesday, April 10, 2007 12:22 PM:
>> 
>>> Do you know if any specific IOS version does not map Prec to EXP
>>> automatically when traffic enters PE as IP packet and exit as
>>> labeled packet? 
>>> 
>>> I have seen some books maping IP Prec to EXP manually and this made
>>> me wonder if this is purely didatic or there is IOSs that needs it.
>> 
>> I haven't come across a case where a manual mapping was required,
>> the PE automatically sets the EXP bits accordingly (TOS reflection)..
>> 
>> There are DiffServ tunneling modes where you want/need to alter the
>> default behavior. See
>>
<http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature
>> _guide09186a0080110bd5.html#wp1131096> for addtl. info.. 
>> 
>> 	oli
>> 
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