Hi Gyan,
On 01/04/2020 03:43, Gyan Mishra wrote:
Thank you both for your feedback. That really helps a lot and clarifies.
So flex-algo can be used with SR-TE as part of the policy specifying a
delay metric and also be used as part of the IGP flex algo cSPF.
yes.
Their might be some slight nuances but overall as far as features for
both SR-MPLS & SRv6 the SR-TE policy would require binding SID and have
similarities with lose or strict with prefix-sid or ad-sid specified
correct and all same features and functionality. Correct?
yes.
Also for inter-as or inter-domain SR - for both SR-MPLS or SRv6 the
SR-TE w/ binding sid could be used as well in place of traditional
BGP-LU for inter-as or csc. Correct?
yes.
So operators have the option to stay with inter-as BGP-LU or go with
SR-TE which is more attractive and powerful with simplicity.
agree.
thanks,
Peter
Kind regards
Gyan
On Tue, Mar 31, 2020 at 5:15 AM Ketan Talaulikar (ketant)
<[email protected] <mailto:[email protected]>> wrote:
Hi Gyan,
To add to what Peter has clarified, SR Policy architecture also
supports SRv6 (as you've pointed out in the references) - loose and
strict paths as well as steering for colored BGP routes.
Thanks,
Ketan
-----Original Message-----
From: spring <[email protected]
<mailto:[email protected]>> On Behalf Of Peter Psenak
Sent: 31 March 2020 13:42
To: Gyan Mishra <[email protected]
<mailto:[email protected]>>; SPRING WG <[email protected]
<mailto:[email protected]>>
Subject: Re: [spring] SRV6 - SR-TE support & Flex Alg support ? and
comparison and contrast of those two steering strategies
Hi Gyan,
let me comment on the flex-algo aspect. Please see inline:
On 30/03/2020 23:50, Gyan Mishra wrote:
>
> Does SRv6 support SR-TE and flex Alg?
yes, it does support both.
>
>
> Since SRv6 supports native traffic steering with SRH with end prefix
> sid and end.x adjacency sid you can achieve the basic steering and
> ECMP capability with prefix sid lose or strict hop by hop with every
> node specified in SRH SL.
>
> I want to confirm that SRv6 fully supports all of the SR-TE
> capabilities available with SR-MPLS with static lose or strict paths
> and coloring of vpn flows.
>
> From the SR policy draft I did see that section 4 lists segment
types
> and does appear to support SRv6 sid.
>
>
https://tools.ietf.org/html/draft-ietf-spring-segment-routing-policy-0
> 6
>
>
> 4
>
<https://tools.ietf.org/html/draft-ietf-spring-segment-routing-policy-06#section-4>.
> Segment Types
>
>
>
> A Segment-List is an ordered set of segments represented as
<S1, S2,
> ... Sn> where S1 is the first segment.
>
> Based on the desired dataplane, either the MPLS label stack
or the
> SRv6 SRH is built from the Segment-List. However, the
Segment-List
> itself can be specified using different segment-descriptor
types and
> the following are currently defined:
>
>
> Flex Alg - SRv6 support?
yes.
>
> Flex Alg is orthogonal to SR TE as it provides IGP extensions for
> constrained SPF versus traditional RSVP or SR-TE providing the
> extensions for cSPF - basically another method of steering which as
> well is very powerful tool for operators.
>
> It does appear SRv6 supports flex Alg draft below.
yes.
>
> https://tools.ietf.org/html/draft-ietf-lsr-flex-algo-06
>
> Abstract
>
> IGP protocols traditionally compute best paths over the network based
> on the IGP metric assigned to the links. Many network
deployments
> use RSVP-TE based or Segment Routing based Traffic Engineering to
> enforce traffic over a path that is computed using different
metrics
> or constraints than the shortest IGP path. This document
proposes a
> solution that allows IGPs themselves to compute constraint based
> paths over the network. This document also specifies a way
of using
> Segment Routing (SR) Prefix-SIDs and SRv6 locators to steer
packets
> along the constraint-based paths.
>
>
>
> What are the benefits of using SR-TE over flex Alg and vice versa?
you can think of them as different tools in your SR-TE tool set. You
pick them as you need them. They can be used independently in
parallel or can even be combined together to give you even more
flexibility.
The principal difference is that SR-TE provisions point-to-point
path(s) between two end-points, while flex-algo provides any to any
paths between set of participating nodes.
>
> Also can SR-TE use flex Alg steered paths as the dynamic cSPF paths?
yes
>
> Can SR-TE use and specify flex Alg to be used for traffic steering?
yes
thanks,
Peter
>
>
> Kind regards
>
>
> Gyan
> Verizon
> Cell 301 502-1347
> --
>
> Gyan Mishra
>
> Network Engineering & Technology
>
> Verizon
>
> Silver Spring, MD 20904
>
> Phone: 301 502-1347
>
> Email: [email protected]
<mailto:[email protected]> <mailto:[email protected]
<mailto:[email protected]>>
>
>
>
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--
Gyan Mishra
Network Engineering & Technology
Verizon
Silver Spring, MD 20904
Phone: 301 502-1347
Email: [email protected] <mailto:[email protected]>
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