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Segment Routing: Impact on Software Defined Networks

March 27, 2013 - 4 Comments

Segment routing (SR) is a concept that’s been working its way through the IETF standards process but is finally becoming ready for real world deployment. It’s a network technology that provides enhanced packet forwarding behavior while minimizing the need for maintaining awareness of mass volumes of network state. SR satisfies essential requirements for application-enabled routing in software defined networks, including the ability to provide strict network performance guarantees, efficient use of network resources and very high scalability for application-based transactions. Segment Routing relies on a small number of extensions to IS-IS and OSPF and can operate with an MPLS or an IPv6 data plane and integrates with the rich multi-service capabilities of MPLS such as L3VPN, VPWS, VPLS, E-VPN, etc.

With respect to protection, SR provides automatic traffic protection without any topological restrictions. The network protects traffic against link and node failures without requiring additional signaling in the network which also simplifies deployment. Existing IP fast re-route (FRR) technology, in combination with the explicit routing capabilities in Segment Routing, guarantees full sub-50 millisecond protection coverage. In addition, traffic protection does not impose any additional signaling requirements.

What’s really driving a lot of interest now is how SR delivers compelling innovations within our Cisco Open Network Environment (ONE) framework to support and embrace SDN technologies.  Segment routing can provide strict network performance guarantees, efficient use of network resources and very high scalability for application-based transactions while using minimal state information to meet these requirements.

Clarence Filsfils, Cisco Distinguished Engineer spoke at the recent MPLS & Ethernet World Congress on the subject of Cisco’s effort to lead in implementing Segment Routing (his slides are available on here). His team already has Early Field Trial software available for several identified customers who want to evaluate the concept. Hear what else Clarence has to say on the subject:

Note: We’ll have a full copy of Clarence’s video presentation from the conference organizers in about a week and will include a link to it then.

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  1. Very informative article, I just learned a little more about the high tech world. Still a lot to learn.

    • atleast now i know the video talked about segment routing . otherwise the complete video clip is talking about something great without a name 😉

  2. Why is Cisco fooling around with this technology ? Why not focus your efforts on LISP which is a much better technology and offers some leadership to the industry.

    This looks like yet another a nasty hack on MPLS to solve the wrong problem. Or am I missing something.

    • Yes I really do think you missing something.

      LISP is not a core technology but overlay like L3VPN
      LISP is pull technology and as such will never provide strigent convergence.

      Segment Routing does provide garantee 50 ms convegence, transport for mpls based services (l3vpn, l2vpn,..), mpls optimization and sdn integration.