Re: [spring] draft-hu-spring-segment-routing-proxy-forwarding-14: Post convergence path

Stewart Bryant <stewart.bryant@gmail.com> Mon, 26 July 2021 20:28 UTC

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From: Stewart Bryant <stewart.bryant@gmail.com>
In-Reply-To: <d6381303-7dc6-f3b0-2d9a-a1a215589e73@cisco.com>
Date: Mon, 26 Jul 2021 21:28:01 +0100
Cc: Stewart Bryant <stewart.bryant@gmail.com>, Shraddha Hegde <shraddha=40juniper.net@dmarc.ietf.org>, "spring@ietf.org" <spring@ietf.org>
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To: Peter Psenak <ppsenak=40cisco.com@dmarc.ietf.org>
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Subject: Re: [spring] draft-hu-spring-segment-routing-proxy-forwarding-14: Post convergence path
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+1

S



> On 26 Jul 2021, at 21:26, Peter Psenak <ppsenak=40cisco.com@dmarc.ietf.org> wrote:
> 
> Hi Shraddha,
> 
> On 26/07/2021 22:16, Shraddha Hegde wrote:
>> WG,
>> Regarding Peter’s comment on the mic that TI-LFA can divert from post convergence path when SRLG is used for computation I would like to clarify > that an operator is expected to do planning for the post convergence
>> path accounting for the SRLG failures.
> 
> TI-LFA does not always guarantee that backup path follows the post-convergence path.
> 
> It depends on what is the type of the backup computed and what is the actual failure. When the two do not match, we can not guarantee the backup path being equal to post convergence one.
> 
> An example is when you are calculating a node protecting backup, but the actual failure is a link failure, your backup path may not be the same as the post convergence one.
> 
> thanks,
> Peter
> 
> 
> 
>> draft-hu-spring-segment-routing-proxy-forwarding-14 is proposing a mechanism which will
>> divert the traffic based on nodes being upgraded to support the protection. The paths
>> could be quite divergent from post-convergence path and an operator would be expected
>> to do planning to ensure these paths have sufficient bandwidth to take on traffic.
>> Rgds
>> Shraddha
>> Juniper Business Use Only
> 
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