Segment Routing: Impact on Software Defined Networks 段路由对SDN的影响

Segment Routing: Impact on Software Defined Networks

段路由对SDN的影响

Stephen Liu | March 27, 2013 at 7:18 am PST

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.

SR是一个概念，虽然当前在IETF标准组织中处于工作中进程，但是它已经准备好在实际网络中部署了。它是一种能够提供增强型包转发行为的路由协议，并且减少维持大量网络状态的需求。在SDN中SR可以为基于某些应用特定的路由规划提供最根本的满足，包括提供严格网络性能保障的能力，有效利用网络资源的能力以及基于业务交易的高扩展能力。SR依靠对ISIS和OSPD极少的扩展，能够在MPLS或IPv6数据层面工作并且能够兼容丰富MPLS多业务能力，比如L3VPN, VPWS, VPLS, E-VPN等。

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.

基于保护的重要性，SR提供无拓扑限制的自动流量保护机制。SR网络实现链路和节点故障的流量保护不需要部署额外的信令，从而简化了网络部署。已有的IP FRR技术结合SR的显式路由能力可以实现50ms级的保护倒换。另外，流量保护不会带来任何附加的信令需求。

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.

真正引起一些兴趣的是SR将如何对cisco的ONE架构进行创新，ONE架构是用于支持和整合SDN技术的。SR提供严格网络性能保障的能力，有效利用网络资源的能力以及基于业务交易的高扩展能力是在使用非常少的状态信息下实现的。

（这段是Clarence Filsfils, Cisco Distinguished Engineer做Segment Routing 演讲前的引词）