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Re: Is TI-LFA compatible with the default SR algorithm?

Stewart Bryant <stewart.bryant@gmail.com> Thu, 14 June 2018 12:58 UTC

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Subject: Re: Is TI-LFA compatible with the default SR algorithm?
To: Alexander Vainshtein <Alexander.Vainshtein@ecitele.com>, "stephane.litkowski@orange.com" <stephane.litkowski@orange.com>
Cc: Michael Gorokhovsky <Michael.Gorokhovsky@ecitele.com>, "draft-ietf-spring-segment-routing.authors@ietf.org" <draft-ietf-spring-segment-routing.authors@ietf.org>, "spring@ietf.org" <spring@ietf.org>, "rtgwg@ietf.org" <rtgwg@ietf.org>, "draft-bashandy-rtgwg-segment-routing-ti-lfa.authors@ietf.org" <draft-bashandy-rtgwg-segment-routing-ti-lfa.authors@ietf.org>
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From: Stewart Bryant <stewart.bryant@gmail.com>
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Date: Thu, 14 Jun 2018 13:58:32 +0100
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On 14/06/2018 13:45, Alexander Vainshtein wrote:
>
> Please note that RFC 5286 explicitly states that it is only applicable 
> to intra-domain routing only with OSPF or IS-IS as IGP.
>
> It does not mention the possibility of local policies overriding 
> shortest path routing provided by these protocols.
>

10 years ago when we were thinking about these early IPFRR schemes I 
don't recall anyone considering anything
other that simple Dijkstra paths for IP. The exception perhaps was 
Not-Via, but in that case base connectivity
and repair had orthogonal address spaces. I am not sure is that is the 
direction with policy and flex, but
that may be a required direction for unconditional safety.

- Stewart

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