Segment Routing Part II: Traffic Engineering

Segment Routing Part II: Traffic Engineering

<p>As more and more Service Providers and Enterprises operate a single network infrastructure to support an ever-increasing number of services, the ability to custom fit transport to application needs is of paramount importance.</p><p>In that respect, network operators have been exploring Traffic Engineering techniques for some years now but have obviously run into many scaling issues preventing them from having an end-to-end, fine-grained control over the myriad services they offer.</p><p><strong>Segment Routing Traffic Engineering (SR-TE)</strong> has changed that game and has become the undisputed solution to deliver Traffic Engineering capabilities at scale.</p><p>Segment Routing enables the deployment of end-to-end policies across independent Metro, WAN and Data Center domains. This avoids complex protocol conversion between network domains while maintaining scalability – simplification at its best.</p><p>A broad range of advanced network services can be delivered by leveraging efficient SR-native algorithms, such as low-delay paths based on dynamically measured link-delays. SR-TE can also compute and maintain disjoint paths (not sharing the same fiber, not sharing the same duct and so on …). This improves network resiliency and end-user satisfaction.</p><p>The IOS XR built-in <strong>SR Path Computation Element (SR PCE)</strong> extends the SR-TE capabilities by offering path computation and path maintenance services to headend routers. The horizontally scalable SR PCE solution enables reaching very high scalability.</p><p>The <strong>Automated Steering</strong> functionality uses existing BGP communities to automatically steer service traffic in the desired SR Policy.</p><p>While in the past provisioning multi-domain services (L2VPN & L3VPN) came with complexity and scalability issues, the SR-TE <strong>On-Demand Next Hop (ODN)</strong> innovation has drastically scaled and automated the establishment of inter-domain policies. Routes no longer need to be redistributed, policies no longer need to be pre-configured. ODN automatically triggers generation of an end-to-end SR Policy upon signaling of a service route. This tremendously simplifies the network operation.</p><p><strong>IGP SR Flexible Algorithm (Flex-Algo)</strong> enriches the SR-TE solution by adding additional segments having different properties than the IGP Prefix segments. The network operator defines the properties of these Flex-Algo segments, hereby providing the ultimate flexibility.</p><p>Flex-Algo makes multiple optimizations of the same physical network infrastructure along various dimensions possible – one can be optimized for low-latency vs. another one for bandwidth, one can offer disjoint paths via two distinct planes. IGP SR Flex-Algo readily provides a simple support for 5G slices.</p>