Segment Routing: a Comprehensive Survey of Research Activities, Standardization Efforts and Implementation Results

Fixed and mobile telecom operators, enterprise network operators and cloud providers strive to face the challenging demands coming from the evolution of IP networks (e.g. huge bandwidth requirements, integration of billions of devices and millions of services in the cloud). Proposed in the early 2010s, Segment Routing (SR) architecture helps face these challenging demands, and it is currently being adopted and deployed. SR architecture is based on the concept of source routing and has interesting scalability properties, as it dramatically reduces the amount of state information to be configured in the core nodes to support complex services. SR architecture was first implemented with the MPLS dataplane and then, quite recently, with the IPv6 dataplane (SRv6). IPv6 SR architecture (SRv6) has been extended from the simple steering of packets across nodes to a general network programming approach, making it very suitable for use cases such as Service Function Chaining and Network Function Virtualization. In this paper we present a tutorial and a comprehensive survey on SR technology, analyzing standardization efforts, patents, research activities and implementation results. We start with an introduction on the motivations for Segment Routing and an overview of its evolution and standardization. Then, we provide a tutorial on Segment Routing technology, with a focus on the novel SRv6 solution. We discuss the standardization efforts and the patents providing details on the most important documents and mentioning other ongoing activities. We then thoroughly analyze research activities according to a taxonomy. We have identified 8 main categories during our analysis of the current state of play: Monitoring, Traffic Engineering, Failure Recovery, Centrally Controlled Architectures, Path Encoding, Network Programming, Performance Evaluation and Miscellaneous...Comment: SUBMITTED TO IEEE COMMUNICATIONS SURVEYS & TUTORIAL

Segment routing for effective recovery and multi-domain traffic engineering

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

Network service chaining using segment routing in multi-layer networks

Network service chaining, originally conceived in the network function virtualization (NFV) framework for software defined networks (SDN), is becoming an attractive solution for enabling service differentiation enforcement to microflows generated by data centers, 5G fronthaul and Internet of Things (IoT) cloud/fog nodes, and traversing a metro-core network. However, the current IP/MPLS-over optical multi-layer network is practically unable to provide such service chain enforcement. First, MPLS granularity prevents microflows from being conveyed in dedicated paths. Second, service configuration for a huge number of selected flows with different requirements is prone to scalability concerns, even considering the deployment of a SDN network. In this paper, effective service chaining enforcement along traffic engineered (TE) paths is proposed using segment routing and extended traffic steering mechanisms for mapping micro-flows. The proposed control architecture is based on an extended SDN controller encompassing a stateful path computation element (PCE) handling microflow computation and placement supporting service chains, whereas segment routing allows automatic service enforcement without the need for continuous configuration of the service node. The proposed solution is experimentally evaluated in segment routing over an elastic optical network (EON) network testbed with a deep packet inspection service supporting dynamic and automatic flow enforcement using Border Gateway Protocol with Flow Specification (BGP Flowspec) and OpenFlow protocols as alternative traffic steering enablers. Scalability of flow computation, placement, and steering are also evaluated showing the effectiveness of the proposed solution

Towards the deployment of software defined networks over satellites - an in-laboratory demonstration for GEO satellite services

Traditional satellite communications missions are based on artificial satellites that can communicate with ground stations. This type of network provides wide-area coverage as well as resilient communications. Satellite systems are expected to be merged with the introduction of 5G/6G mobile systems to offer seamless connection and ubiquitous coverage for users worldwide. SDN/NFV are two of the most important enabling technologies for deploying new 5G/6G mobile network architectures, and they are widely used in telecommunications to deliver different services. Its method is based on network softwarization, which abstracts the physical infrastructure by separating the functionality of the hardware. Furthermore, using SDN, it is possible to reconfigure the network in flexible topologies that adapt to the performance necessary at any given time, thereby maximizing resources and lowering costs. SDN/NFV, on the other hand, relies on a strong and continuous network layer to construct a control plane and deploy VNF. However, establishing a stable link is difficult in constellations of several LEO/MEO satellites. TALENT is a software platform created with the purpose of supplying satellite and ground connection by coordinating satellite and terrestrial systems from a single location, developed under the SaTG5 project that defined the integration of satellite solutions for 5G. Regardless of these solutions, a robust testbed is required to help in the discovery of novel protocols for delivering and orchestrating network services over satellite networks that take dynamic network architecture on satellite constellations into account. This thesis addresses the lack of a testbed for deploying VNF via a satellite network, as well as the orchestration and deployment of VNF across various satellite constellations. Its main contribution is an update to TALENT to allow it to work with newer Open Source MANO versions, and a testbed for deploying a VNF across a simulated satellite network based on the OpenSand satellite simulation tool.Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructur