Re: [spring] SRV6 - SR-TE support & Flex Alg support ? and comparison and contrast of those two steering strategies

[Gyan Mishra <[e-mail]>]

Thank you

Gyan

On Sun, Apr 5, 2020 at 12:09 PM Peter Psenak <[e-mail]> wrote:

> 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)
> > <[e-mail] <mailto:[e-mail]>> 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 <[e-mail]
> >     <mailto:[e-mail]>> On Behalf Of Peter Psenak
> >     Sent: 31 March 2020 13:42
> >     To: Gyan Mishra <[e-mail]
> >     <mailto:[e-mail]>>; SPRING WG <[e-mail]
> >     <mailto:[e-mail]>>
> >     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: [phone]
> >      >
> >      > Email: [e-mail]
> >     <mailto:[e-mail]> <mailto:[e-mail]
> >     <mailto:[e-mail]>>
> >      >
> >      >
> >      >
> >
> >     _______________________________________________
> >     spring mailing list
> >     [e-mail] <mailto:[e-mail]>
> >     https://www.ietf.org/mailman/listinfo/spring
> >
> >
> >
> > --
> >
> > Gyan  Mishra
> >
> > Network Engineering & Technology
> >
> > Verizon
> >
> > Silver Spring, MD 20904
> >
> > Phone: [phone]
> >
> > Email: [e-mail] <mailto:[e-mail]>
> >
> >
> >
>
> --

Gyan  Mishra

Network Engineering & Technology

Verizon

Silver Spring, MD 20904

Phone: [phone]

Email: [e-mail]