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

IP and ATM integration: A New paradigm in multi-service internetworking

ATM is a widespread technology adopted by many to support advanced data communication, in particular efficient Internet services provision. The expected challenges of multimedia communication together with the increasing massive utilization of IP-based applications urgently require redesign of networking solutions in terms of both new functionalities and enhanced performance. However, the networking context is affected by so many changes, and to some extent chaotic growth, that any approach based on a structured and complex top-down architecture is unlikely to be applicable. Instead, an approach based on finding out the best match between realistic service requirements and the pragmatic, intelligent use of technical opportunities made available by the product market seems more appropriate. By following this approach, innovations and improvements can be introduced at different times, not necessarily complying with each other according to a coherent overall design. With the aim of pursuing feasible innovations in the different networking aspects, we look at both IP and ATM internetworking in order to investigating a few of the most crucial topics/ issues related to the IP and ATM integration perspective. This research would also address various means of internetworking the Internet Protocol (IP) and Asynchronous Transfer Mode (ATM) with an objective of identifying the best possible means of delivering Quality of Service (QoS) requirements for multi-service applications, exploiting the meritorious features that IP and ATM have to offer. Although IP and ATM often have been viewed as competitors, their complementary strengths and limitations from a natural alliance that combines the best aspects of both the technologies. For instance, one limitation of ATM networks has been the relatively large gap between the speed of the network paths and the control operations needed to configure those data paths to meet changing user needs. IP\u27s greatest strength, on the other hand, is the inherent flexibility and its capacity to adapt rapidly to changing conditions. These complementary strengths and limitations make it natural to combine IP with ATM to obtain the best that each has to offer. Over time many models and architectures have evolved for IP/ATM internetworking and they have impacted the fundamental thinking in internetworking IP and ATM. These technologies, architectures, models and implementations will be reviewed in greater detail in addressing possible issues in integrating these architectures s in a multi-service, enterprise network. The objective being to make recommendations as to the best means of interworking the two in exploiting the salient features of one another to provide a faster, reliable, scalable, robust, QoS aware network in the most economical manner. How IP will be carried over ATM when a commercial worldwide ATM network is deployed is not addressed and the details of such a network still remain in a state of flux to specify anything concrete. Our research findings culminated with a strong recommendation that the best model to adopt, in light of the impending integrated service requirements of future multi-service environments, is an ATM core with IP at the edges to realize the best of both technologies in delivering QoS guarantees in a seamless manner to any node in the enterprise

VeriTable: Fast Equivalence Verification of Multiple Large Forwarding Tables

Due to network practices such as traffic engineering and multi-homing, the number of routes---also known as IP prefixes---in the global forwarding tables has been increasing significantly in the last decade and continues growing in a super linear trend. One of the most promising solutions is to use smart Forwarding Information Base (FIB) aggregation algorithms to aggregate the prefixes and convert a large table into a small one. Doing so poses a research question, however, i.e., how can we quickly verify that the original table yields the same forwarding behaviors as the aggregated one? We answer this question in this paper, including addressing the challenges caused by the longest prefix matching (LPM) lookups. In particular, we propose the VeriTable algorithm that can employ a single tree/trie traversal to quickly check if multiple forwarding tables are forwarding equivalent, as well as if they could result in routing loops or black holes. The VeriTable algorithm significantly outperforms the state-of-the-art work for both IPv4 and IPv6 tables in every aspect, including the total running time, memory access times and memory consumption.Comment: INFOCOM 201

Improving the Accuracy of the Internet Cartography

As the global Internet expands to satisfy the demands of the ever-increasing connected population, profound changes are occurring in its interconnection structure. The pervasive growth of IXPs and CDNs, two initially independent but synergistic infrastructure sectors, have contributed to the gradual flattening of the Internet’s inter-domain hierarchy with primary routing paths shifting from backbone networks to peripheral peering links. At the same time the IPv6 deployment has taken off due to the depletion of unallocated IPv4 addresses. These fundamental changes in Internet dynamics has obvious implications for network engineering and operations, which can be benefited by accurate topology maps to understand the properties of this critical infrastructure. This thesis presents a set of new measurement techniques and inference algorithms to construct a new type of semantically rich Internet map, and improve the state of the art in Internet cartography. The author first develops a methodology to extract large-scale validation data from the Communities BGP attribute, which encodes rich routing meta-data on BGP messages. Based on this better-informed dataset the author proceeds to analyse popular assumptions about inter-domain routing policies and devise a more accurate model to describe inter-AS business relationships. Accordingly, the thesis proposes a new relationship inference algorithm to accurately capture both simple and complex AS relationships across two dimensions: prefix type, and geographic location. Validation against three sources of ground-truth data reveals that the proposed algorithm achieves a near-perfect accuracy. However, any inference approach is constrained by the inability of the existing topology data sources to provide a complete view of the inter-domain topology. To limit the topology incompleteness problem the author augments traditional BGP data with routing policy data obtained directly from IXPs to discover massive peering meshes which have thus far been largely invisible

Automatic provisioning in multi-domain software defined networking

Multi-domain Software Defined Networking (SDN) is the extension of the SDN paradigm to multi-domain networking and the interconnection of different administrative domains. By utilising SDN in the core telecommunication networks, benefits are found including improved traffic flow control, fast route updates and the potential for routing centralisation across domains. The Border Gateway Protocol (BGP) was designed three decades ago, and efforts to redesign interdomain routing that would include a replacement or upgrade to the existing BGP have yet to be realised. For the near real-time flow control provided by SDN, the domain boundary presents a challenge that is difficult to overcome when utilising existing protocols. Replacing the existing gateway mechanism, that provides routing updates between the different administrative domains, with a multi-domain centralised SDN-based solution may not be supported by the network operators, so it is a challenge to identify an approach that works within this constraint. In this research, BGP was studied and selected as the inter-domain SDN communication protocol, and it was used as the baseline protocol for a novel framework for automatic multi-domain SDN provisioning. The framework utilises the BGP UPDATE message with Communities and Extended Communities as the attributes for message exchange. A new application called Inter-Domain Provisioning of Routing Policy in ONOS (INDOPRONOS), for the framework implementation, was developed and tested. This application was built as an ONOS controller application, which collaborated with the existing ONOS SDN-IP application. The framework implementation was tested to verify the information exchange mechanism between domains, and it successfully carried out the provisioning actions that are triggered by that exchanged information. The test results show that the framework was successfully verified. The information carried inside the two attributes can successfully be transferred between domains, and it can be used to trigger INDOPRONOS to create and install new alternative intents to override the default intents of the ONOS controller. The intents installed by INDOPRONOS immediately change the route of the existing connection, which demonstrated that the correct request sent from the other domain, can carry out a modification in network settings inside a domain. Finally, the framework was tested using a bandwidth on demand use case. In this use case, a customer network administrator can immediately change the network service bandwidth which was provided by the service provider, without any intervention from the service provider administrator, based on an agreed-predefined configuration setting. This ability will provide benefits for both customer and service provider, in terms of customer satisfaction and network operations efficiency

Deploying ITS Scenarios Providing Security and Mobility Services Based on IEEE 802.11p Technology

Botany & plant science

IP and ATM - a position paper

This paper gives a technical overview of different networking technologies, such as the Internet, ATM. It describes different approaches of how to run IP on top of an ATM network, and assesses their potential to be used as an integrated services network