Segment Routing (SR) uses a list of instructions, called segments, to direct a packet through a network. Each segment has a unique identifier called a Segment Identifier (SID) and is represented by an MPLS label on the packet. The sequence of segments describes how the packet should be forwarded and processed as it moves through the network. Each segment is executed by a node, and then deleted from the list to expose the next instruction. This process continues until all segments have been executed and the packet reaches its destination. With Segment Routing, network operators can choose explicit or dynamic paths to steer traffic using network resources beyond the Interior Gateway Protocol's shortest path. This allows operators to avoid congestion or choose an alternative path when the shortest path is not optimal for the service. The motivation for Segment Routing – Traffic Engineering (SR-TE) is to address the complexity and scalability problems of the older traffic engineering techniques, while adapting to the dynamic nature of the current and future traffic patterns, which require better flexibility and programmability in IP transport networks.
What is Traffic Engineering?
Traffic engineering aims to optimize network performance, resource utilization, and reliability to reduce costs, complexity, and provide better services to end-users. To achieve this, network operators set performance objectives based on industry regulations, SLAs and application requirements. They gather information on traffic patterns, existing and planned network resources, and the current network state to calculate the changes needed to achieve the desired network state. Control is then applied to the network to reach the new state. This process was once done manually, but is becoming automated. If the network doesn't meet the performance objectives, the process starts again to form an adaptive feedback system.
SR-TE allows for flexible and programmable paths in the network that can be explicitly defined or calculated dynamically. This reduces complexity and scalability problems of older TE techniques and supports advanced protection schemes, efficient resource utilization, and traffic performance.
To learn more, download our Segment Routing Traffic Engineering for IP Transport White Paper or learn more about our IP Optical Solutions