Re: [Pce] New Version Notification for draft-lu-ospf-area-tlv-01.txt

Hi Wenhu & WG, 

I wanted to mention following points with respect to this discussion:

(1)     I feel its better to keep the scope of CSPF algorithm limited to
single area. In case PCE functionality resides at ABR router which has
visibility into multiple areas, it better to apply BRPC as before and the
same PCE can compute VSPT(i) and then VSPT(i-1) . I am not in favor of CSPF
doing inter-area path computation by combining TED of both areas. 

(2)    In case of ABR is not an LSR: Based on local policy BN may choose not
to advertise the BN Discovery TLV [draft-dhody-pce-bn-discovery-ospf], also
if PCE discovers the BN, it can easily choose to ignore it if that node is
not in the TED.  

Regards,

Dhruv

****************************************************************************
***********
Dhruv Dhody, Senior Technical Leader, Huawei Technologies, Bangalore, India,
Ph. +91-9845062422

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From: Wenhu Lu [mailto:wenhu.lu@ericsson.com] 
Sent: Wednesday, July 20, 2011 3:03 AM
To: Dhruv Dhody; 'JP Vasseur'
Cc: pce@ietf.org
Subject: RE: [Pce] New Version Notification for
draft-lu-ospf-area-tlv-01.txt

Thanks Dhruv for the summary.

At least the authors of the two drafts have the same vision that advertising
OSPF area IDs will help PCE's multi-area path computation, so that operators
do not have to configure manually the list of boundary routers.

PCEers, please voice your opinions whether it's a good idea to automate the
discovery of the OSPF area IDs.

If we agree that automating the ABR provisioning is a good thing, please be
advised that the rationale and approaches of the two drafts are quite
different. 

draft-lu-ospf-area-tlv focuses on one thing, i.e. to enable CSPF to do
multi-area path computation with no need of manual ABR provisioning. Here're
several key points (please refer to the draft for detail):

1. An OSPF Area-ID-TLV is introduced. This TLV tells whether and how CSPF
can extend its LSP computation to across area boundaries.

2. The originating point is OSPF's TE function. The TLV is kept under OSPF
TE extensions (like router-address TLV and link TLV). This is to ensure that
the ABR is an LSR capable of transit TE traffic. This is important because
an ABR is not necessary an LSR.

3. From CSPF point-of-view, if the area-id info is readily available in TED,
CSPF's job will be easy (please see use-cases 1 and 2). It doesn't need to
talk to OSPF or other network components to acquire ABR information. The
change to CSPF is minimal.

4. It addresses only multi-area path computation. It does not address
multi-AS path computation.

draft-dhody-pce-bn-discovery-ospf is not tied with TE but kept generic (some
use-cases would be helpful). It focuses on both multi-area and multi-AS. I
believe the topic is also important.

Thanks,

-wenhu

  _____  

From: Dhruv Dhody [mailto:dhruvd@huawei.com] 
Sent: Thursday, July 14, 2011 9:49 PM
To: 'JP Vasseur'
Cc: Wenhu Lu; pce@ietf.org
Subject: RE: [Pce] New Version Notification for
draft-lu-ospf-area-tlv-01.txt

Hi, 

BN Discovery draft was kept generic for the purpose of ease and
extensibility. 

I see further growth in this ID as the work on PCE-VPN and PCE-INTER-LAYER
advances. 

As a WG, we need consensus on the Motivation and Need for this kind of work.

Then we can discuss on the way we achieve this via area-tlv in OSPF-TE or a
generic Boundary Node Discovery. 

Regards,

Dhruv

Note: the obvious difference between the IDs

1. draft-lu focuses on ABRs with TE property for PCEs to compute LSPs.
draft-dhody focuses on the discovery of both ABRs/ASBRs.

2. draft-lu's area TLV is part of ospf TE extension. draft-dhody's (Boundary
Node Discovery) BND TLV is generic.

****************************************************************************
***********
Dhruv Dhody, Senior Tecnical Leader, Huawei Tecnologies, Bangalore, India,
Ph. +91-9845062422

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
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  _____  

From: JP Vasseur [mailto:jpv@cisco.com] 
Sent: Thursday, July 14, 2011 3:50 PM
To: Dhruv Dhody
Cc: 'Wenhu Lu'; pce@ietf.org
Subject: Re: [Pce] New Version Notification for
draft-lu-ospf-area-tlv-01.txt

Hi Dhruv,

On Jul 14, 2011, at 6:15 AM, Dhruv Dhody wrote:

Dear Wenhu and WG, 

I wanted to mention here in WG about the idea presented in IETF-78 in
Maastricht.  

OSPF Protocol Extensions for Boundary Node Discovery (BND)

http://datatracker.ietf.org/doc/draft-dhody-pce-bn-discovery-ospf/

During the meeting WG can evaluate if any collaboration and/or consensus be
reached in this area. 

Would you want to share with the WG how you see the positioning of these two
ID ?

Thanks.

JP.

Thanks & Regards,

Dhruv

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

Dhruv Dhody, Senior Tecnical Leader, Huawei Tecnologies, Bangalore, India,
Ph. +91-9845062422

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!

-----Original Message-----
From: pce-bounces@ietf.org [mailto:pce-bounces@ietf.org] On Behalf Of Wenhu
Lu
Sent: Thursday, July 14, 2011 6:46 AM
To: pce@ietf.org
Subject: [Pce] New Version Notification for draft-lu-ospf-area-tlv-01.txt

Dear all, 

A new version of I-D, draft-lu-ospf-area-tlv-01.txt has been successfully
submitted by Wenhu Lu and posted to the IETF repository.
http://tools.ietf.org/html/draft-lu-ospf-area-tlv-01

There's quite a bit of updates over the 00 version, mainly on the
clarifications, motivations, and use-cases, thanks to all that provided
comments and inputs.

I'll be grateful for your further review and comments before the upcoming
IETF when I plan to use the PCE slot to address the concerns and issues.

Regards,

-wenhu

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