RE: TE/CT Configuration scalability

[Lionel.Silman@ecitele.com]

As far as I can see there is a considerable difference bteween the inter-AS
Diffserv case and the inter-AS DS-TE case.

In Diffserv, the DIFFSERV TLV uses a standard PSC coding.  This promotes
the possibility of  agreement between the AS. They have to agree on the
PSC/Classes implemented and perhaps on policing, etc. There are no coding
issues.

In the DS-TE, there is no standard CLASSTYPE coding.  As Tony Li writes, a
"standard" mapping may be useful. But given that the idea of TE/CT is to
define a  limited number of combinations from a set prevalent alternatives,
this may be difficult.  In the absence of a standard mapping, it is
presumably necessary to have a mechanism to explicitly map between the
TE/CT codes of every AS pair.

Do you agree that this is required? if so, is it feasible?

Lionel Silman,  System, Optical Networks Division, ECI Telecom



                                                                                                        
                      "Francois Le                                                                      
                      Faucheur                 To:      "Ina Minei" <ina@juniper.net>,                  
                      \(flefauch\)"            <Lionel.Silman@ecitele.com>                              
                      <flefauch@cisco.         cc:      <te-wg@ops.ietf.org>, "FLF"                     
                      com>                     <flefauch@cisco.com>                                     
                                               Subject: RE: TE/CT Configuration scalability             
                      02/07/2004 11:42                                                                  
                                                                                                        
                                                                                                        



Hello,

Expanding on Ina's response.

The TE-Class Mapping need NOT be the same in different Autonomous
Systems which are span by a given inter-AS DS-TE LSP. It may be that AS1
supports 4 preemption priorities within its AS for CT1, while AS2 only
supports 2 preemption priorities within its AS for CT1.

Now, the two AS administrators certainly have to carefully agree on a
number of things before they can support inter-AS LSPs; like which CTs
they are allowed to use across ASes,  which preemption, how much maximum
bandwidth etc. But but this is how Diffserv works anyway independently
of DS-TE: for inter-AS Diffserv, operators have to agree on which
classes they want to share, which marking, what maximum rate for each,
and then configure mechansisms such as Traffic Conditioning accordingly.
DS-TE just fits in this existing Diffserv mode of operations.

Cheers

Francois

>> -----Original Message-----
>> From: owner-te-wg@ops.ietf.org
>> [mailto:owner-te-wg@ops.ietf.org] On Behalf Of Ina Minei
>> Sent: jeudi 1 juillet 2004 19:26
>> To: Lionel.Silman@ecitele.com
>> Cc: te-wg@ops.ietf.org
>> Subject: Re: TE/CT Configuration scalability
>>
>>
>>           Lionel,
>>
>>           I assume your question is "can I establish an inter-as
>> diffserv-te
>> lsp given the requirement for uniform TE-class
>> configuration" ? The answer
>> is yes.
>>
>>           The reason for having a requirement for uniform TE-Class
>> configuration is because of the way IGP siganling is defined in the
>> te-proto draft. If instead of only advertising 8 values out of the 64
>> possible (ct, prio) combinations we would have advertised
>> all 64, there
>> wouldn't have been the concept of TE-classes or the
>> requirement to keep
>> them uniform.
>>
>>           The only thing we get from the requirement is to be able to
>> consistently set up an LSP conforming to some SLAs within
>> one domain. So
>> what happens when you cross to a different domain? All you
>> need to do is
>> translate the LSP's SLAs to the necessary parameters in the
>> new domain.
>>
>>           There is no requirement to signal the TE-class matrix across
>> domains.
>>
>>                                   Ina
>>
>> On Thu, 1 Jul 2004 Lionel.Silman@ecitele.com wrote:
>>
>> >
>> >
>> >
>> >
>> > draft-ietf-tewg-diff-te-proto-07, "Protocol extensions for
>> support of
>> > Differentiated-Service-aware MPLS Traffic Engineering" states:-
>> >
>> > "To ensure coherent DS-TE operation, the network administrator MUST
>> > configure exactly the same TE-Class Mapping on all LSRs of
>> the DS-TE
>> > domain"
>> >
>> > How does this idea of identical TE/CT configuration work
>> over multiple
>> > domains? Is there any possibility of interoperability?
>> >
>> >
>> -------------------------------------------------------------
>> ---------------------------------------
>> >
>> > Lionel Silman,  System, Optical Networks Division, ECI Telecom
>> > Tel    Work: +972 (3) 9266007; Home: +972 (3) 6417464
>> >
>> >
>>
>>