Subject: Re: [Pce] Inter-domain-p2mp-procedures

From: Quintin Zhao <[email-masked]>
Date: Fri, 18 Dec 2009 15:40:48 -0500

Dhruv,

Thanks for your comments and suggestions.

For the pre-computed backup tree, I think that it should be best tree
available during the computation time period while satisfying the
link/node/path diversity constrains. 

For the backup tree's Path-diversity, this might be depending on the
failures we are trying to protect. If we only want to protect the link
failures, then the backup tree may only need the link diversity from the
primary tree.  For the node failures, then we may need the backup tree which
has the node diversity from the primary tree. We also may need the link
direction diversity backup tree from the primary backup tree for certain
scenarios. We will add a paragraph in the draft to specify all the path
diversity level we should support when we compute the backup tree.

Yes, the inter-domain p2mp procedure need to support all re-optimization
scenarios specified in draft-ietf-pce-pcep-p2mp-extensions in the procedure
draft. We will specify this in the new version of the draft.

Thanks,

Quintin

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

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

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

Message: 2

Date: Tue, 15 Dec 2009 12:08:52 +0530

From: dhruv dhody <[email-masked]>

Subject: Re: [Pce] Inter-domain-p2mp-procedures

To: 'Quintin Zhao' <[email-masked]>, [email-masked]

Message-ID: <[email-masked]>

Content-Type: text/plain; charset="us-ascii"

Hello Quintin, 

I have following comments - 

For Pre-computed Backup Core Tree

1) Is the Backup tree, the next Best core-tree [MCT or SPT]?

2) How path-diverse should the Backup tree be? 

We may need to support all re-optimization scenarios similar to P2MP

Intra-domain cases [explained in draft-ietf-pce-pcep-p2mp-extensions]. 

Thanks & Regards,

Dhruv

Huawei Technologies Co.,Ltd.

Bangalore, India

****************************************************************************

***********

This e-mail and attachments contain confidential information from HUAWEI,

which is intended only for the person or entity whose address is listed

above. Any use of the information contained herein in any way (including,

but not limited to, total or partial disclosure, reproduction, or

dissemination) by persons other than the intended recipient's) is

prohibited. If you receive this e-mail in error, please notify the sender by

phone or email immediately and delete it!

 

On Dec 14, 2009, at 10:15 PM, Quintin Zhao wrote:

> Hello PCE'rs,

> I would like to follow-up on some discussions from our PCE WG  

> session last

> month. Specifically regarding Dajiang's failure and recomputation

> observations on our draft. We are very interested to hear comments  

> regarding

> the need for computing secondary paths in the event of failure.  

> Currently

> our thinking is to recompute the sub-tree based in the domain where  

> the

> failure has occurred. In this case we would not need to perform a

> recalculation of the entire tree. We could also recompute the entire  

> tree,

> and avoid the failed areas, as long as the TED has the updated  

> topology.

> Realistically one might have a backup core tree pre-computed so you  

> can

> switch over in the event of failure. There are also other  

> considerations.

> Would a partial recomputation provide a "worse" SPT or MCT tree, or  

> would a

> full tree recomputation provide a "better" SPT or MCT? I can think of

> scenarios for both a partial and full recomputation, so perhaps we  

> need to

> implement both but allow the PCC to decide when to issue a partial  

> or full

> recomputation based on some criterion.

> Thanks,

> Quintin

> _______________________________________________

> Pce mailing list

> [email-masked]

> https://www.ietf.org/mailman/listinfo/pce