Abstract
Segment routing is an emerging traffic engineering technique relying on Multi-protocol Label-Switched (MPLS) label stacking to steer traffic using the source-routing paradigm. Traffic flows are enforced through a given path by applying a specifically designed stack of labels (i.e., the segment list). Each packet is then forwarded along the shortest path toward the network element represented by the top label. Unlike traditional MPLS networks, segment routing maintains a per-flow state only at the ingress node; no signaling protocol is required to establish new flows or change the routing of active flows. Thus, control plane scalability is greatly improved. Several segment routing use cases have recently been proposed. As an example, it can be effectively used to dynamically steer traffic flows on paths characterized by low latency values. However, this may suffer from some potential issues. Indeed, deployed MPLS equipment typically supports a limited number of stacked labels. Therefore, it is important to define the proper procedures to minimize the required segment list depth. This work is focused on two relevant segment routing use cases: dynamic traffic recovery and traffic engineering in multi-domain networks. Indeed, in both use cases, the utilization of segment routing can significantly simplify the network operation with respect to traditional Internet Protocol (IP)/MPLS procedures. Thus, two original procedures based on segment routing are proposed for the aforementioned use cases. Both procedures are evaluated including a simulative analysis of the segment list depth. Moreover, an experimental demonstration is performed in a multi-layer test bed exploiting a software-defined-networking-based implementation of segment routing.
Highlights
Segment routing (SR) has recently been proposed within the Internet Engineering Task Force (IETF) to provide traffic engineering (TE) by simplifying control plane operation [1]
SR natively implements equal cost multi-path (ECMP)-aware routing, i.e., in the case of multiple shortest paths toward the destination the traffic is automatically load-balanced on a per-flow basis
This paper proposes, implements, and experimentally validates two original procedures based on segment routing for addressing dynamic traffic recovery and interdomain TE solutions in multi-layer networks
Summary
Segment routing (SR) has recently been proposed within the Internet Engineering Task Force (IETF) to provide traffic engineering (TE) by simplifying control plane operation [1]. Using SR labels may have a global meaning, and a signaling protocol is not required to perform explicit routing and a per-flow state is maintained only at the ingress node where the segment list is enforced This approach significantly simplifies the control plane operation, especially in multi-layer networks, where SR can eliminate the need to establish and maintain hierarchical instances of generalized MPLS (GMPLS) LSPs [2]. SR natively implements equal cost multi-path (ECMP)-aware routing, i.e., in the case of multiple shortest paths toward the destination the traffic is automatically load-balanced on a per-flow basis This characteristic simplifies the control plane operation where complex configurations are often required to properly deploy load-balancing policies. They are experimentally validated in a test bed deploying the SR approach in a software-defined networking (SDN) environment
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