Segment routing for traffic engineering and effective recovery in low-earth orbit satellite constellations

Low-Earth Orbit Satellite Constellations(LEO-SCs)provide global,high-speed,and low latency Internet access services,which bridges the digital divide in the remote areas.As inter-satellite links are not supported in initial deployment(i.e.the Starlink),the communication between satellites is based on ground stations with radio frequency signals.Due to the rapid movement of satellites,this hybrid topology of LEO-SCs and ground stations is time-varying,which imposes a major challenge to uninterrupted service provisioning and network management.In this paper,we focus on solving two notable problems in such a ground station-assisted LEO-SC topology,i.e.,traffic engineering and fast reroute,to guarantee that the packets are forwarded in a balanced and uninterrupted manner.Specifically,we employ segment routing to support the arbitrary path routing in LEO-SCs.To solve the traffic engineering problem,we proposed two source routings with traffic splitting algorithms,Delay-Bounded Traffic Splitting(DBTS)and DBTS+,where DBTS equally splits a flow and DBTS+favors shorter paths.Simu-lation results show that DBTS+can achieve about 30%lower maximum satellite load at the cost of about 10%more delay.To guarantee the fast recovery of failures,two fast reroute mechanisms,Loop-Free Alternate(LFA)and LFA+,are studied,where LFA pre-computes an alternate next-hop as a backup while LFA+finds a 2-segment backup path.We show that LFA+can increase the percentage of protection coverage by about 15%.

A comprehensive survey on Segment Routing Traffic Engineering

Traffic Engineering(TE)enables management of traffic in a manner that optimizes utilization of network resources in an efficient and balanced manner.However,existing TE solutions face issues relating to scalability and complexity.In recent years,Segment Routing(SR)has emerged as a promising source routing paradigm.As one of the most important applications of SR,Segment Routing Traffic Engineering(SR-TE),which enables a headend to steer traffic along specific paths represented as ordered lists of instructions called segment lists,has the capability to overcome the above challenges due to its flexibility and scalability.In this paper,we conduct a comprehensive survey on SR-TE.A thorough review of SR-TE architecture is provided in the first place,reviewing the core components and implementation of SR-TE such as SR Policy,Flexible Algorithm and SR-native algorithm.Strengths of SR-TE are also discussed,as well as its major challenges.Next,we dwell on the recent SR-TE researches on routing optimization with various intents,e.g.,optimization on link utilization,throughput,QoE(Quality of Experience)and energy consumption.Afterwards,node management for SR-TE are investigated,including SR node deployment and candidate node selection.Finally,we discuss the existing challenges of current research activities and propose several research directions worth of future exploration.

基于P4的Segment Routing 设计方案

本文结合Segment Routing业内常使用的SR-MPLS转发平面的规则,设计了基于P4的Segment Routing方案。P4程序部分包括了基本转发逻辑和Segment Routing标签处理逻辑,用于在P4交换机上编译运行实现数据平面功能。使用ONOS控制器做Segment Routing的控制平面指导流表的下发,底层P4交换机从ONOS控制器的通告中得知对每个Segment的处理方法。

基于Segment Routing的金融跨数据中心网络设计与验证

由于金融机构业务的自身特点,其网络建设也比较特殊,物理层多采用"单区专线专用"的方式进行数据隔离,在网络层和应用层多采用IP路由技术,然后逐跳配置策略路由来进行路径控制,存在资源复用能力及突发情况应对能力不足。下一代金融跨中心网络互联方案设计以Segment Routing技术为基础,引入逻辑隔离、虚拟传输隧道的理念对网络进行了重新设计,并对该方案进行实际组网测试。在功能、性能都达到预期之后,方案在中国银联跨数据中心互联网络中部署应用。

Traffic Engineering in Dynamic Hybrid Segment Routing Networks

The emergence of Segment Routing(SR)provides a novel routing paradigm that uses a routing technique called source packet routing.In SR architecture,the paths that the packets choose to route on are indicated at the ingress router.Compared with shortest-path-based routing in traditional distributed routing protocols,SR can realize a flexible routing by implementing an arbitrary flow splitting at the ingress router.Despite the advantages of SR,it may be difficult to update the existing IP network to a full SR deployed network,for economical and technical reasons.Updating partial of the traditional IP network to the SR network,thus forming a hybrid SR network,is a preferable choice.For the traffic is dynamically changing in a daily time,in this paper,we propose a Weight Adjustment algorithm WASAR to optimize routing in a dynamic hybrid SR network.WASAR algorithm can be divided into three steps:firstly,representative Traffic Matrices(TMs)and the expected TM are obtained from the historical TMs through ultrascalable spectral clustering algorithm.Secondly,given the network topology,the initial network weight setting and the expected TM,we can realize the link weight optimization and SR node deployment optimization through a Deep Reinforcement Learning(DRL)algorithm.Thirdly,we optimize the flow splitting ratios of SR nodes in a centralized online manner under dynamic traffic demands,in order to improve the network performance.In the evaluation,we exploit historical TMs to test the performance of the obtained routing configuration in WASAR.The extensive experimental results validate that our proposed WASAR algorithm has superior performance in reducing Maximum Link Utilization(MLU)under the dynamic traffic.

Intelligent Segment Routing: Toward Load Balancing with Limited Control Overheads

Segment routing has been a novel architecture for traffic engineering in recent years.However,segment routing brings control overheads,i.e.,additional packets headers should be inserted.The overheads can greatly reduce the forwarding efficiency for a large network,when segment headers become too long.To achieve the best of two targets,we propose the intelligent routing scheme for traffic engineering(IRTE),which can achieve load balancing with limited control overheads.To achieve optimal performance,we first formulate the problem as a mapping problem that maps different flows to key diversion points.Second,we prove the problem is nondeterministic polynomial(NP)-hard by reducing it to a k-dense subgraph problem.To solve this problem,we develop an ant colony optimization algorithm as improved ant colony optimization(IACO),which is widely used in network optimization problems.We also design the load balancing algorithm with diversion routing(LBA-DR),and analyze its theoretical performance.Finally,we evaluate the IRTE in different real-world topologies,and the results show that the IRTE outperforms traditional algorithms,e.g.,the maximum bandwidth is 24.6% lower than that of traditional algorithms when evaluating on BellCanada topology.

Vector Segment Routing for Large-Scale Multilayer Satellite Network

With the expansion of satellite constellation,routing techniques for small-scale satellite networks have problems in routing overhead and forwarding efficiency.This paper proposes a vector segment routing method for large-scale multi layer satellite networks.A vector forwarding path is built based on the location between the source and the destination.Data packets are forwarded along this vector path,shielding the influence of satellite motion on routing forwarding.Then,a dynamic route maintenance strategy is suggested.In a multi layer satellite network,the low-orbit satellites are in charge of computing the routing tables for one area,and the routing paths are dynamically adjusted in the area in accordance with the network.The medium-orbit satellites maintain the connectivity of vector paths in multiple segmented areas.The forwarding mode based on the source and destination location improves the forwarding efficiency,and the segmented route maintenance mode decreases the routing overhead.The simulation results indicate that vector segment routing has significant performance advantages in end-to-end delay,packet loss rate,and throughput in a multi layer satellite network.We also simulate the impact of routing table update mechanism on network performance and overhead and give the performance of segmented vector routing in multi layer low-orbit satellite networks.

Traffic Engineering Based on Deep Reinforcement Learning in Hybrid IP/SR Network

Segment Routing(SR)is a new routing paradigm based on source routing and provide traffic engineering(TE)capabilities in IP network.By extending interior gateway protocol(IGP),SR can be easily applied to IP network.However,upgrading current IP network to a full SR one can be costly and difficult.Hybrid IP/SR network will last for some time.Aiming at the low flexibility problem of static TE policies in the current SR networks,this paper proposes a Deep Reinforcement Learning(DRL)based TE scheme.The proposed scheme employs multi-path transmission and use DRL to dynamically adjust the traffic splitting ratio among different paths based on the network traffic distribution.As a result,the network congestion can be mitigated and the performance of the network is improved.Simulation results show that our proposed scheme can improve the throughput of the network by up to 9%than existing schemes.

基于应用驱动的商业银行智能核心网流量模型设计与实践

数字化转型浪潮下,兴业银行针对“构建连接一切的能力,打造最佳生态赋能银行”的发展目标,提出了新一代核心网建设项目。实践中,兴业银行基于应用驱动的核心网SD-WAN流量工程解决方案,通过引入多种新兴广域网流量工程技术,并结合应用驱动流量模型,构建了行内所有分支机构之间端到端的流量调度能力,显著提升了核心网的流量管理水平。

面向5G和固网综合承载的智能城域网探索

主要介绍中国联通河北省分公司在雄安开展了新型智能城域网的建设试点,在承载网利用Segment Routing/EVPN新技术实现了包含5G业务在内的固移业务综合承载和统一调度。分别从业务需求、网络规划、创新技术、实际业务测试等角度入手,成功验证了智能城域网的综合承载及SDN智能调度的能力,为今后城域网的发展提供了依据。

全球智能加速网络系统建设策略研究

网络领域的所有变革,始终围绕着一个字“快”。时至今日,传统广域网建设已比较完善,全球电信运营商正面临着企业转型及网络融合,使得原本泾渭分明的网络界限逐步模糊。基于完善的基础设施,进行轻量化改造,融合多种加速技术,构建全球智能加速网络实现业网融合,为用户提供最优网络体验大势所趋。

OpenDaylight 在跨数据中心网络中的应用

当前,跨数据中心网络互联以MPLS等传统技术方案为主。研究利用传统技术所演化的新技术以及传统设备所提供的新接口,根据各类接口的各自特点,使用不同的协议,对网络进行不同操作和监控。同时,重点梳理OpenDaylight控制器自身各种南向接口的实现情况及使用方法,并加以实例研究。最后,介绍如何使用统一的北向接口进行应用层开发,从而加速跨数据中心网络部署与运维。

Fast network restoration with equivalent cooperative routing

Aiming at the problem of failure recovery in current networks,a fast failure recovery method based on equivalent cooperative routing is proposed.Firstly,the transmission path between the source and destination nodes is divided into several non-overlapping path segments.Next,backup paths are deployed for each link in the path segment through segmented routing technology,which ensures fast routing recovery after failure.Additionally,in order to avoid damaging the QoS of the data stream through the failure recovery process,the transmission is guaranteed by the intersegment QoS complement.The experimental results show that the proposed method has a low failure recovery delay under a relatively small flow table cost.

A Solution Supporting Secure Transmission of Big Data

Traditional Internet protocol networks cannot provide the service of selecting a secure path to transmit various types of data with specific security constraints.First,to solve the“secure path transmission”problem,this paper first proposes a search-transmit model for secure network path transmission,i.e.,to find a multi-attribute optimized path that meets the specific security requirements in the search phase,and then transmit the packets along the optimized path in the transmission phase.Second,we propose a solution to the search-transmit model.The idea of the solution is to use the particle swarm optimization algorithm to search for a secure path that meets the multi-attribute requirements and then set the source route on the router to control the packet transmission.Finally,a prototype system based on network function virtualization is developed to evaluate the feasibility and performance of the proposed solution.Experimental results show that the proposed solution outperforms existing algorithms in terms of performance.