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

[Gyan Mishra <[e-mail]>]

Does SRv6 support SR-TE and flex Alg?


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-06

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?

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.

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?

Also can SR-TE use flex Alg steered paths as the dynamic cSPF paths?

Can SR-TE use and specify flex Alg to be used for traffic steering?


Kind regards


Gyan
Verizon
Cell 301 502-1347
-- 

Gyan  Mishra

Network Engineering & Technology

Verizon

Silver Spring, MD 20904

Phone: [phone]

Email: [e-mail]