Re: [Lsr] New draft on Flex-Algorithm Bandwidth Constraints

[William Britto A J <[e-mail]>]

Hi Gyan,

This draft aims to provide the protocol constructs to define a flex-algorithm which is suitable for sending high bandwidth traffic. Flex-Algo is a very useful feature for network consolidation use-cases which requires different metric-types for SPF. We are trying introduce the protocol constructs to simplify the use of metric based on bandwidth via Flex-Algo.

This draft does not attempt to do bandwidth management nor reservation like what RSVP does. For LDP based networks that use igp metric relative to bandwidth, Flex-Algo provides an easy alternate.

Thanks,
William

From: Gyan Mishra <[e-mail]>
Date: Saturday, 27 February 2021 at 9:40 PM
To: Robert Raszuk <[e-mail]>
Cc: DECRAENE Bruno IMT/OLN <[e-mail]>, Rajesh M <[e-mail]>, Shraddha Hegde <[e-mail]>, William Britto A J <[e-mail]>, [e-mail] <[e-mail]>
Subject: Re: [Lsr] New draft on Flex-Algorithm Bandwidth Constraints
[External Email. Be cautious of content]


Hi William & Co-authors

>From first read of the draft it does appear your are trying to apply RSVP TE PCALC path and reserve message link attributes constraints such as concept of affinity bits to exclude low bandwidth or delay of individual links without taking into account all of what RSVP TE is reserving of bandwidth in the end to end path with the Path and Reserve message.  As mentioned Looking at individual links will not provide the end to end path view or bandwidth requirements for the entire path to be reserved as accomplished by RSVP TE.

As Tony and Robert have mentioned I agree this is a good first step but does need more refinement to make useful.

Kind Regards

Gyan

On Sat, Feb 27, 2021 at 7:24 AM Robert Raszuk <[e-mail]<mailto:[e-mail]>> wrote:
Hi William & co-authors,

I read the draft and have two basic questions.

1.
Both bw & delay can be used as defined in the draft to construct new forwarding topologies. But how practical such topologies would be in the real life when 40GB links may be heavily occupied with bursty traffic and 10G links can sit idle ? I suppose you are trying to address the case where say 12 gbps holographic stream needs to be sent across a network.. But then I don't think if sending it in a single flow instead of spreading into many sub-flows and use as much as possible ecmp would not be a better option.

2.
Likewise how good is my accumulated link delay value if in between there are deep buffer network elements and say egress queuing to each link (which max is unaccounted for in your draft) can significantly alter the end to end delay ? Have you consider to add MAX_EGRESS_QUEUE_DELAY on a per link basis (still as static value).  So if some traffic is delay sensitive we will have a much better accuracy not to get into a trap of queuing related delays.

Thx a lot,
Robert.


On Fri, Feb 26, 2021 at 8:37 AM William Britto A J <bwilliam=[e-mail]<mailto:[e-mail]>> wrote:
All,

We would like to draw your attention to a new ID: https://datatracker.ietf.org/doc/html/draft-hegde-lsr-flex-algo-bw-con-00<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-hegde-lsr-flex-algo-bw-con-00__;!!NEt6yMaO-gk!U3HBQwaZL7T4mjz-MUHE7VjFtnOyNghGDh5vwJXUXkHdMxlravmRvJwdZ8sz2YPxkw$>

The draft talks about introducing link bandwidth related constraints in Flex-Algorithm which can be used to define a Flex-Algorithm based on bandwidth based metric.

Please review. Any questions and comments are welcome.

Thanks,
William


From: [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>
Date: Monday, 22 February 2021 at 10:56 PM
To: Bruno Decraene <[e-mail]<mailto:[e-mail]>>, Rajesh M <[e-mail]<mailto:[e-mail]>>, Rajesh M <[e-mail]<mailto:[e-mail]>>, Shraddha Hegde <[e-mail]<mailto:[e-mail]>>, William Britto A J <[e-mail]<mailto:[e-mail]>>, William Britto A J <[e-mail]<mailto:[e-mail]>>
Subject: New Version Notification for draft-hegde-lsr-flex-algo-bw-con-00.txt
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A new version of I-D, draft-hegde-lsr-flex-algo-bw-con-00.txt
has been successfully submitted by Shraddha Hegde and posted to the
IETF repository.

Name:           draft-hegde-lsr-flex-algo-bw-con
Revision:       00
Title:          Flexible Algorithms Bandwidth Constraints
Document date:  2021-02-22
Group:          Individual Submission
Pages:          21
URL:            https://urldefense.com/v3/__https://www.ietf.org/archive/id/draft-hegde-lsr-flex-algo-bw-con-00.txt__;!!NEt6yMaO-gk!QGg36p91zPfVMznYY91xs-zx70Qp5BE1nJx-Thnl14sTCkvwgOjEzjGBtD3v6TruoA$<https://urldefense.com/v3/__https:/www.ietf.org/archive/id/draft-hegde-lsr-flex-algo-bw-con-00.txt__;!!NEt6yMaO-gk!QGg36p91zPfVMznYY91xs-zx70Qp5BE1nJx-Thnl14sTCkvwgOjEzjGBtD3v6TruoA$>
Status:         https://urldefense.com/v3/__https://datatracker.ietf.org/doc/draft-hegde-lsr-flex-algo-bw-con/__;!!NEt6yMaO-gk!QGg36p91zPfVMznYY91xs-zx70Qp5BE1nJx-Thnl14sTCkvwgOjEzjGBtD1VexjHPQ$<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/draft-hegde-lsr-flex-algo-bw-con/__;!!NEt6yMaO-gk!QGg36p91zPfVMznYY91xs-zx70Qp5BE1nJx-Thnl14sTCkvwgOjEzjGBtD1VexjHPQ$>
Htmlized:       https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/draft-hegde-lsr-flex-algo-bw-con__;!!NEt6yMaO-gk!QGg36p91zPfVMznYY91xs-zx70Qp5BE1nJx-Thnl14sTCkvwgOjEzjGBtD3X5nPQbA$<https://urldefense.com/v3/__https:/datatracker.ietf.org/doc/html/draft-hegde-lsr-flex-algo-bw-con__;!!NEt6yMaO-gk!QGg36p91zPfVMznYY91xs-zx70Qp5BE1nJx-Thnl14sTCkvwgOjEzjGBtD3X5nPQbA$>
Htmlized:       https://urldefense.com/v3/__https://tools.ietf.org/html/draft-hegde-lsr-flex-algo-bw-con-00__;!!NEt6yMaO-gk!QGg36p91zPfVMznYY91xs-zx70Qp5BE1nJx-Thnl14sTCkvwgOjEzjGBtD2aqSYcuQ$<https://urldefense.com/v3/__https:/tools.ietf.org/html/draft-hegde-lsr-flex-algo-bw-con-00__;!!NEt6yMaO-gk!QGg36p91zPfVMznYY91xs-zx70Qp5BE1nJx-Thnl14sTCkvwgOjEzjGBtD2aqSYcuQ$>


Abstract:
   Many networks configure the link metric relative to the link
   capacity.  High bandwidth traffic gets routed as per the link
   capacity.  Flexible algorithms provides mechanisms to create
   constraint based paths in IGP.  This draft documents a set of
   bandwidth related constraints to be used in Flexible Algorithms.





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