Subject: Re: [Pce] request timeslot for draft-wang-pce-inter-as-extentions-01

From: 王磊 <[email-masked]>
Date: Mon, 25 Jul 2011 12:25:22 +0800

Hi, Xuerong and PCEers

I have read the draft. It provides an alternate method that extends
BRPC and PCEP protocol to get TE information of Inter-AS biderectional
links. In my opinion, It is useful for the smooth upgrade of existing
MPLS/GMPLS networks to support Inter-AS bidirectional path
computation, because it need not any extension or modification to the
IGP (such as OSPF and IS-IS) used in MPLS/GMPLS-enabled
routers/switches. However, the method of IGP extension is also
applicable and suitable for new network-equipments. So, I think there
is no conflict between these two metods. The draft could be used in
the scenario where the IGP extension of Inter-AS biderectional links
can not be supported.

Thanks.

Lei Wang
Tsinghua University, Beijing, China
[email-masked] or [email-masked]

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From: JP Vasseur <[email-masked]>
Date: Mon, 25 Jul 2011 08:30:05 -0400

Thanks for your feed-back. It would be interesting to hear from the WG if indeed
we need two methods. To each specific problem we can certainly find a number
of way to solve it, but let's try to make sure that we do not specify a new technique 
if we can use what exist today.

WG ?

Thanks.

JP.
On Jul 25, 2011, at 12:25 AM, 王磊 wrote:

> _______________________________________________
> Pce mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/pce
>

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From: [email-masked]
Date: Mon, 25 Jul 2011 23:16:47 +0800

Hi JP,

IMO, we don't need two methods. The method of extending IGP may impact on 
large aspect.
Extending BRPC and PCEP defined in this draft is enough.

Thanks,

Xihua

JP Vasseur <[email-masked]> 
发件人:  [email-masked]
2011-07-25 下午 08:30

收件人
王磊 <[email-masked]>
抄送
[email-masked]
主题
Re: [Pce] request timeslot for draft-wang-pce-inter-as-extentions-01

Thanks for your feed-back. It would be interesting to hear from the WG if 
indeed
we need two methods. To each specific problem we can certainly find a 
number
of way to solve it, but let's try to make sure that we do not specify a 
new technique 
if we can use what exist today.

WG ?

Thanks.

JP.

Hi, Xuerong and PCEers

Thanks.

Lei Wang

---

From: JP Vasseur <[email-masked]>
Date: Mon, 25 Jul 2011 13:20:47 -0400

Hi,

On Jul 25, 2011, at 11:16 AM, [email-masked] wrote:

> 
> Hi JP, 
> 
> IMO, we don't need two methods. The method of extending IGP may impact on large aspect. 

So let the WG decide which one of the methods is most appropriate

Thanks.

JP.

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From: Fatai Zhang <[email-masked]>
Date: Wed, 27 Jul 2011 01:55:19 +0800

Hi all,

RFC5392 is a kind of mechamism and it is already there.

Why we need to define another solution based on some nonexistent assumption?

Fatai

Thanks
  ----- Original Message ----- 
  From: JP Vasseur 
  To: [email-masked] 
  Cc: [email-masked] ; [email-masked] ; 王磊 
  Sent: Tuesday, July 26, 2011 1:20 AM
  Subject: Re: [Pce] request timeslot for draft-wang-pce-inter-as-extentions-01

  Hi,

    Hi JP, 

  Thanks.

  JP.

    Thanks, 

    Xihua 

          JP Vasseur <[email-masked]> 
          发件人:  [email-masked]
          2011-07-25 下午 08:30 
         收件人 王磊 <[email-masked]>  
                抄送 [email-masked]  
                主题 Re: [Pce] request timeslot for draft-wang-pce-inter-as-extentions-01 

    WG ? 

    Thanks. 

    JP. 

    Hi, Xuerong and PCEers

    Thanks.

    Lei Wang

------------------------------------------------------------------------------

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From: Ramon Casellas <[email-masked]>
Date: Tue, 26 Jul 2011 21:42:03 +0200

> So let the WG decide which one of the methods is most appropriate

Dear PCErs,

Just my (subjective) opinion:

IIUC, the motivation behind this draft is the lack of upstream TE 
attributes in inter-AS links (due to the lack of proxy), which is 
necessary to compute bidirectional LSPs.

For this, the draft extended BRPC, proposing that the PCEP response 
includes links that respect the constraints from of the request, for the 
reverse direction, sent by the downstream PCE. Per se, I am not against 
augmented procedures where applicable.

However, I believe that the original/main requirement not only applies 
to BRPC but also when a Path is "segmented" (i.e. a (generic) client 
requests a path from an entry node to an exit node, even without the 
VSPT to later compose a path) or with H-PCE. I tend to think that (even 
if sometimes the contrary seems easier) TED management (including 
"augmented TED" with knowledge of border nodes, areas, and inter-domain 
links) and Path Computation functions should be kept, as much as 
possible, decoupled. Since the PCE architecture does not specify how a 
PCE obtains the TED, I would prefer to maintain both concepts separated, 
and embedding the links along with the VSPT does not seem to fit, much 
alike alternative solutions which could be proposed where PCEs could 
inform each other of TE attributes of AS links (embedded in 
notifications). After consideration, this may not be a good idea.

I am aware that my comment is of little help since, even if I prefer 
that the scope of responsibility of PCE(i) starts in its entry border 
nodes and PCE(i-1) trims the VSPT based first on the Inter-As links and 
second on its domain, I am not solving the original problem/requirement 
other than "PCE(i) must also know the TE attributes of the upstream 
link" but I don't know / consider how

Thanks and best regards
Ramon

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From: JP Vasseur <[email-masked]>
Date: Tue, 26 Jul 2011 18:04:57 -0400

That was my question too