Subject: RE: [Pce] RE: I-D ACTION:draft-vijay-somen-pce-bgp-interas-te-path-01.txt

From: "Vijayanand C - TLS, Chennai." <[email-masked]>
Date: Thu, 1 Feb 2007 11:18:46 +0530

Are you suggesting that  BGP should propagate all possible next-hops/As
paths and regular path selection process avoided for all prefixes which
can be destinations of inter-AS TE tunnels ?

The inter-AS TE link information can be made aware only to the ASes on
either side of the inter-AS link by the IGP. It may not be possible to
propagate it beyond that ( or can it ?).

So some of the possible AS paths found by BGP( if we propagate all
next-hops/aspaths in bgp) may not be worth trying for path setup (by
BRPC) because of violation of some TE constraint. 

In our proposal we can pick the paths which are really feasible, since
we have the inter-AS graph, and then invoke methods like BRPC 

Regards

Vijay 

 

-----Original Message-----
From: JP Vasseur [mailto:[email-masked]] 
Sent: Thursday, February 01, 2007 1:19 AM
To: Vijayanand C - TLS, Chennai.
Cc: [email-masked]
Subject: Re: [Pce] RE: I-D
ACTION:draft-vijay-somen-pce-bgp-interas-te-path-01.txt 

Hi,

On Jan 25, 2007, at 9:32 AM, Vijayanand C - TLS, Chennai. wrote:

Hello all,

We have submitted the following I-D, please send in your

comments/suggestions

* speaking as a technical contributor *

   In [BRPC], a method to optimally compute a inter-domain TE 

   path for MPLS and GMPS LSPs using the PCE architecture detailed in 

   [PCE_ARCH] is described. However the method described requires the 

   list of Autonomous systems or domains to be determined apriori. 

   Determining the list of ASes/domains to be traversed to reach a 

   destination, satisfying the TE constraints is non-trivial. It 

   requires knowledge of the inter-AS connectivity and the TE 

   characteristics of the inter-AS links along with the knowledge of 

   the available paths within each of the ASes/domains. BGP contains 

   information on the list of ASes to be traversed to reach a 

   destination, however BGP route selection and decision process 

   truncates most of the feasible paths, and it also does not carry 

   the TE characteristics of the inter-AS links and path availability 

   within a domain.  

What does prevent you from relying on BGP to provide you all possible
paths toward 

a specific destination skipping the regular path selection process for
specific routes (see

proposals made in the past) and then use BRPC as currently specified?
The Inter-AS TE

link could easily be obtained via the IGP with minor additions.

This is in my opinion a fundamental question that must first be
addressed before 

moving forward.

Thanks.

JP.

Regards

Vijay

-----Original Message-----

From: [email-masked] [mailto:[email-masked]] 

Sent: Tuesday, January 23, 2007 2:20 AM

To: [email-masked]

Subject: I-D ACTION:draft-vijay-somen-pce-bgp-interas-te-path-01.txt 

A New Internet-Draft is available from the on-line Internet-Drafts 

directories.

            Title                  : A BGP based method to compute
inter-AS Traffic

engineering Label Switched Paths with PCE

            Author(s)          : C. Vijayanand, S. Bhattacharya

            Filename           :

draft-vijay-somen-pce-bgp-interas-te-path-01.txt

            Pages               : 26

            Date                 : 2007-1-22

The ability to compute an optimal path for setting up Traffic 

   engineering Label Switched Paths spanning multiple autonomous 

   systems managed by different operators has been a key requirement in 

   MPLS and GMPLS networks. This document specifies a method of 

   computing inter-AS paths consisting of a list of ASes to be 

   traversed and a list of TE-Tunnels to be traversed in each AS. The 

   method described here uses BGP speakers in the PCEs of each AS to 

   distribute the inter-AS connectivity information and the TE-Tunnels 

   in each AS to its neighbors to facilitate the construction of an 

   inter-AS topology graph which can be used for computing inter-AS

    paths.

A URL for this Internet-Draft is:

http://www.ietf.org/internet-drafts/draft-vijay-somen-pce-bgp-interas-te

-path-01.txt

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From: JP Vasseur <[email-masked]>
Date: Fri, 2 Feb 2007 17:34:54 -0500

Hi,

Let me first try to make sure of something here. When you write "The  
PCE shall learn the TE
    attributes of the inter-AS TE links and the TE tunnels that exist
    between the ASBRs in the domain."

Are you suggesting to flood via BGP the intra-domain TE LSPs ? In  
other words, suppose the following scenario:

AS1---AS2---AS3
You have a mesh of intra-domain TE LSPs between all ASBRs within AS2.

Are you suggesting to flood in AS1 these TE LSPs (and this for all  
other ASes that might be between AS1 and the destination domain) ?

Thanks.

JP.

On Feb 1, 2007, at 12:48 AM, Vijayanand C - TLS, Chennai. wrote:

> Are you suggesting that  BGP should propagate all possible next- 
> hops/As paths and regular path selection process avoided for all  
> prefixes which can be destinations of inter-AS TE tunnels ?
>
>
> The inter-AS TE link information can be made aware only to the ASes  
> on either side of the inter-AS link by the IGP. It may not be  
> possible to propagate it beyond that ( or can it ?).
>
> next-hops/aspaths in bgp) may not be worth trying for path setup  
> (by BRPC) because of violation of some TE constraint.
>
>
> In our proposal we can pick the paths which are really feasible,  
> since we have the inter-AS graph, and then invoke methods like BRPC
>
>
> Regards
>
> Vijay
>
>
>
>
>
> Subject: Re: [Pce] RE: I-D ACTION:draft-vijay-somen-pce-bgp-interas- 
> te-path-01.txt
>
>
> Hi,
>
>
> What does prevent you from relying on BGP to provide you all  
> possible paths toward
>
> a specific destination skipping the regular path selection process  
> for specific routes (see
>
> proposals made in the past) and then use BRPC as currently  
> specified? The Inter-AS TE
>
> ---------------------------------------------------------------------- 
> -------------------------------------------------
>
>
> The contents of this e-mail and any attachment(s) are confidential  
> and intended for the named recipient(s) only.
>
> this message without the prior written consent of the author of  
> this e-mail is strictly prohibited. If you have
>
> ---------------------------------------------------------------------- 
> -------------------------------------------------
>
>