Prev

Next

工业路由器NBMA网络转化为点到点的链路 当我们使用点到点子接口将NBMA网络转化为点到点的链路时,整个NBMA网络将产生过多的PVC部分互联或全互联的网状结构,但这将产生一定的负面影响,会使网络中产生大量的LSP泛洪流量。我们都知道,运行IS-IS的工业路由器当接收到一个LSP报文后,会将此LSP从除接收接口以外的所有启用了IS-IS协议的接口泛洪出去,以使网络中的其他工业路由器都可以接收到此LSP。但是这种泛洪机制对于存在大量部分互联或全互联的网络将产生过多冗余的LSP扩散。 所谓全互联或全网状网络拓扑,是指所有工业路由器都与其他工业级无线路由器向连接(通常是点到点子接口)。在这样的一个网络中,当一台路由器从某接口收到邻居泛洪过来的LSP后,由于它并不知道这个LSP是否已经被其他邻居工业4g路由器收到,所以会再从其他接口泛洪出去,即使其他工业级4g路由器的链路状态数据库中已经存在这个LSP。如果网络中有n个全网路由器的话,那么网络中的每台工业级LTE路由器都会扩散n-2条冗余的LSP,这样总共被泛洪的多余的LSP将为(n-1)x(n-2),条而这些LSP的扩散是多余。如果每台工业全网通路由器都刷新一条LSP的话,那么这个数量还将会成倍数的增长,导致了大量带宽资源的浪费。 为了解这种在全互联或高度互联的网络中出现的LSP泛洪的冗余现象,IS-IS提供了一种解决方案——IS-IS全通组,也称作Mesh组。IS-IS全通组在RFC2973中进行了定义。所谓全通组,就是假设所有工业3G路由器之间都是完全互联的,每个工业级全网通路由器都会直接收到其他全网通工业级路由器泛洪的原始的LSP的拷贝。 可以将全网工业路由器的接口加入到某个全通组中,一个全网通工业路由器上可以存在多个全通组,全通组内接口之间的LSP泛洪是受限制的,全通组之间的LSP泛洪是正常的操作,未加入全通组的工业级3G路由器接口与全通组之间也是正常的LSP泛洪操作。全网通路由器 ...

更多文章

工业路由器使用CSNP来保证链路状态数据库的完整性 在广播网络中,工业路由器使用CSNP来保证链路状态数据库的完整性,并且只有DIS才会发送工业全网通路由器CSNP报文,DIS发送CSNP报文的间隔为10s。CSNP报文中描述了DIS的链路状态数据库中所有工业级3G路由器LSP的摘要信息。当其他工业级路由器收到DIS发送的CSNP后,会使用CSNP中的LSP摘要信息与与本地的链路状态数据库中的LSP进行比较,进行比较的目的是确定本地链路状态数据库中的信息是否已经同步和完整。如果工业级4g路由器发现本地数据库中缺少某个LSP条目,那么它将使用PSNP向DIS请求这个缺少的LSP条目。这个PSNP报文中包含就是请求的LSP条目的摘要信息。当DIS收到其他全网路由器发送的PSNP报文后,将会发送一个完整的LSP报文,这个LSP就是其他工业无线路由器所缺少的LSP条目。在广播网络中,DIS使用周期性的CSNP报文向网络中发送同步链路状态数据库的信号,而其他工业4g路由器使用PSNP报文来请求缺少的LSP条目。 在IS-IS的点到点类型的网络中,链路状态数据库同步的操作与广播网络中略有不同,而且工业级全网通路由器发送CSNP与PSNP报文的方式和其作用也有一些差别。 在点到点网络中不存在DIS,工业3G路由器不会周期性的发送CSNP报文,CSNP报文只在链路链路被激活时发送一次,而且链路两端的工业级4g路由器都会发送CSNP报文以描述本地链路状态数据库中所有LSP的摘要信息。当工业路由器发送对端发送的CSNP中含有本地缺少的LSP信息时,也会使用PSNP报文向对端请求LSP。当对端收到PSNP报文后,将向请求方发送包含完整LSP信息的LSP报文,这点上与广播网络中的操作是相同的。但是在点到点链路上,收到LSP报文的工业4g路由器还会向对方再次发送一个PSNP报文以对之前收到的LSP进行确认。可以说,在点到点网络中的LSP交换是可靠的。这点与广播网络不同,在广播网络中工业级无线路由器不使用PSNP报文对收到的LSP进行确认,而是通过DIS周期性地发送CSNP报文以弥补广播网络中不可靠的LSP交换。 在点到点链路上,工业路由器使用PSNP对收到的LSP报文进行确认,所以在点到点链路上是可靠的泛洪机制。 IS-IS路由协议支持两种网络类型:广播链路和点到点链路。默认情况下,全网通工业级路由器IS-IS将广播网络和NBMA网络看作是广播类型。对于封装了PPP或HDCL等协议的链路看作是点到点类型。对于NBMA网络中的主接口和点到多点子接口,IS-IS将其看作是广播类型;对于NBMA网络中的点到点子接口,将其看作是点到点类型。IS-IS不像OSPF那样,提供了对NBMA网络(例如Frame-Relay、ATM)的专门支持。对于NBMA网络,全网通工业路由器IS-IS认为其网络拓扑是PVC全互联(mesh)的,就是把它看作广播网络。但如果实际网络拓扑中并不是PVC全互联的结构时,例如部分互联的结构和Hub-Spoke结构,推荐使用点到点类型网络,即使用点到点子接口,以免造成NBMA网络中的链路状态数据库同步出现问题。无线路由器

更多文章

工业级路由器LSP校验和(Checksum) 当工业路由器生成一个LSP后,为了保证LSP中信息的完整性,它将对LSP进行校验和计算,然后封装进LSP的LSP校验和字段(checksum)。校验和的计算包括从LSP中的剩余时间字段之后的字段一直到数据包的末尾,由于剩余时间是一个不断变化的字段,所以校验和计算将不包括这部分内容。校验和主要用于检查被破坏的LSP或者还没有从网络中清除的过期LSP。当一台工业4g路由器收到一个LSP,在将该LSP放入到本地链路数据库和将其再泛洪给其他邻接工业3G路由器之前,会重新计算LSP的校验和,如果校验和与LSP中携带的校验和不一致,则说明此全网通工业级路由器LSP传输过程中已经被破坏。 当工业路由器收到了一个被破坏的LSP后,会采取一个清除的操作。它将该LSP的剩余时间设置为0然后再泛洪到网络中。当网络中的其他工业LTE路由器收到这个剩余时间被置为0的LSP后,会将其本地链路状态数据库中相应的LSP清除。当产生这个被破坏的LSP的源双卡路由器收到这个剩余时间被置为0的LSP并发现这个LSP是自己生成的后,会重新生成一个正确的LSP然后泛洪到网络中。 IS-IS的这种LSP清除操作虽然可以有效的清除网络中被破坏的LSP,给运行工业级4G路由器IS-IS路由协议的网络提供了一种自动修复的能力,但是它也带来了一种负面的影响。如果网络中的介质存在问题,就有可能产生LSP被连续破坏的现象。这些被破坏的LSP会被路由器不断的清除,同时源工业无线路由器也会不断的重新生成新的LSP,这种现象被称为LSP破坏风暴。LSP破坏风暴将消耗大量的网络资源。我们可以对工业级无线路由器进行配置,使其在收到被破坏的LSP后忽略它,即丢弃被破坏的LSP,从而启动清除操作。在后续工业级全网通路由器IS-IS配置章节中将介绍具体的配置方法。 标签:4g路由器...

更多文章

伊林思:中间系统类型工业4G路由器(ISType) 在LSP报头中最后一个字节的中间系统类型(ISType)位占2bit,工业4G路由器的类型。该字段表示了此LSP是来自L1工业路由器还是L2工业级路由器。这也表示了收到此LSP的工业路由器将把这个LSP放到L1链路状态数据库还是L2链路状态数据库。该2bit中01表示L1;11表示L2;00与10未使用。 DIS和伪节点【4g路由器】 LSPID中包括一部分称为伪节点标识符(PseudonodeID),用来标识此LSP是否是由网络中的指定中间系统(DIS,DesignatedIntermediateSystem)为网络产生的伪节点LSP。 在广播类型的网络(LAN)中,IS-IS需要为每个网段选择一个指定中间系统DIS,这里的指定中间系统DIS的作用与OSPF中的指定工业级路由器DR的非常相似。在OSPF网络中,DR用来负责将链路状态信息泛洪到每个非DR工业路由器,并且帮助其进行链路状态数据库的同步。在IS-IS中也是如此,为了使链路状态信息更加准确和实时的同步给网络中的所有全网路由器,并且要减小带宽的利用率和路由器的处理开销,IS-IS也要在广播网络中选举出一个工业级无线路由器(DIS)来达到这个目的。 在IS-IS中选举DIS的过程也是非常简单的。每个运行IS-IS协议的全网通路由器的接口都拥有一个优先级(Priority),默认的优先级为64,同样也可以通过命令手工修改默认的优先级。工业4g路由器之间发送的HelloPDU中将携带接口的优先级信息。每个工业LTE路由器收到网络中其他工业级LTE路由器发送的HelloPDU后,通过比较优先级来进行DIS的选举。优先级数值越大的工业全网路由器将被选举为此网段的DIS。这里与OSPF不同的是,在OSPF中,如果接口的优先级为0,那么这台工业级全网通路由器将被认为没有资格成为此网段的DR。在IS-IS中,如果接口的优先级为0,这仅仅表示最低的优先级,但是此工业级4G路由器还拥有成为DIS的资格。当两台工业全网通路由器的接口优先级相同时,那么拥有更大的SNPA(在LAN中通常为MAC地址)的接口的工业级全网通路由器将成为DIS。在OSPF中如果优先级相同将比较RouterID。 在OSPF中,选举完DR后,还将选举出一个备份DR,BDR(BackupDR),以用来在原先DR出现故障时接替新的DR角色,并重新选举出BDR。但在IS-IS中,将不进行备份DIS的选举。如果DIS出现故障了,其他全网通工业路由器将会重新选举出一个DIS。其次,在OSPF中,DR和BDR的选举是非抢占模式的,也就是说当有更优优先级的路由器加入到现有网络中后,也不会抢占原先DR和BDR的角色。从某种意义上来讲,在OSPF网络中,第一台启动的双卡路由器将成为网络的DR,第二台启动的双路路由器将将成为BDR。与OSPF相比,DIS的选举是抢占的,即当有更优DIS资格双路路由器加入网络后,它会成为网络中新的DIS。这样,每次DIS的变更必须泛洪一组新的LSP。 默认情况下,运行IS-IS的双卡路由器将以每10s的间隔发送HelloPDU。但是对于一个DIS来说,由于它在网络中起到重要的作用,所以它发送HelloPDU的间隔的频率将是其他路由器的3倍,也就是说DIS以每3.3s的间隔发送HelloPDU。这样其他全网通工业路由器可以迅速检测出DIS出现故障并开始新的选举过程,增加了网络的收敛速度。无线路由器

更多文章

用于工业路由器指定策略的路由映射 Route Redistribution redistribute routing-process process-id [tag|metric|metic-type|subnets|route-map] *routing-process:BGP EGP Connected EIGRP IGRP ISIS ISO-IGRP Mobile ODR OSPF RIP and Static *ospf-metric:BGP缺省重分布度量 1 其他协议为20 *tag-value:附加到重分布工业路由器路由的一个32位的值,OSPF没有使用工业级无线路由器路由标记, 可以在用于指定策略的路由映射中引用,缺省标记为0 利用route-map控制重分布,并修改metric值,并做标记 如上图,基于标签来控制工业级路由器路由的重分布 Controlling...

更多文章

twitter

The Development of 5G Network

文章目录 : 产品文章, 伊林思产品FAQ, 其他

5G is the trend of the whole world, today I would like to share you the development of 5G network.
In 2008, the South Korean IT R&D program of “5G mobile communication systems based on beam-division multiple access and relays with group cooperation” was formed.
In 2012, the UK Government announced the establishment of a 5G Innovation Centre at the University of Surrey – the world’s first research centre set up specifically for 5G mobile research.
In 2012, NYU WIRELESS was established as a multidisciplinary research centre, with a focus on 5G wireless research, as well as its use in the medical and computer-science fields. The centre is funded by the National Science Foundation and a board of 10 major wireless companies (as of July 2014) that serve on the Industrial Affiliates board of the centre. NYU WIRELESS has conducted and published channel measurements that show that millimeter wave frequencies will be viable for multi-gigabit-per-second data rates for future 5G networks.
In 2012, the European Commission, under the lead of Neelie Kroes, committed 50 million euros for research to deliver 5G mobile technology by 2020. In particular, The METIS 2020 Project was the flagship project that allowed reaching a worldwide consensus on the requirements and key technology components of the 5G. Driven by several telecommunication companies, the METIS overall technical goal was to provide a system concept that supports 1,000 times higher mobile system spectral efficiency, compared to current LTE deployments. In addition, in 2013, another project has started, called 5GrEEn, linked to project METIS and focusing on the design of green 5G mobile networks. Here the goal is to develop guidelines for the definition of a new-generation network with particular emphasis on energy efficiency, sustainability and affordability.
In November 2012, a research project funded by the European Union under the ICT Programme FP7 was launched under the coordination of IMDEA Networks Institute (Madrid, Spain): i-JOIN (Interworking and JOINt Design of an Open Access and Backhaul Network Architecture for Small Cells based on Cloud Networks). iJOIN introduces the novel concept of the radio access network (RAN) as a service (RANaaS), where RAN functionality is flexibly centralized through an open IT platform based on a cloud infrastructure. iJOIN aims for a joint design and optimization of access and backhaul, operation and management algorithms, and architectural elements, integrating small cells, heterogeneous backhaul and centralized processing. Additionally to the development of technology candidates across PHY, MAC, and the network layer, iJOIN will study the requirements, constraints and implications for existing mobile networks, specifically 3GPP LTE-A.
In January 2013, a new EU project named CROWD (Connectivity management for eneRgy Optimised Wireless Dense networks) was launched under the technical supervision of IMDEA Networks Institute, to design sustainable networking and software solutions for the deployment of very dense, heterogeneous wireless networks. The project targets sustainability targeted in terms of cost effectiveness and energy efficiency. Very high density means 1000x higher than current density (users per square meter). Heterogeneity involves multiple dimensions, from coverage radius to technologies (4G/LTE vs. Wi-Fi), to deployments (planned vs. unplanned distribution of radio base stations and hot spots).
In September 2013, the Cyber-Physical System (CPS) Lab at Rutgers University, NJ, started to work on dynamic provisioning and allocation under the emerging cloud radio-access network (C-RAN). They have shown that the dynamic demand-aware provisioning in the cloud will decrease the energy consumption while increasing the resource utilization. They also have implemented a test bed for feasibility of C-RAN and developed new cloud-based techniques for interference cancellation. Their project is funded by the National Science Foundation.
In November 2013, Chinese telecom equipment vendor Huawei said it will invest $600 million in research for 5G technologies in the next five years. The company’s 5G research initiative does not include investment to productize 5G technologies for global telecom operators. Huawei will be testing 5G technology in Malta.
In 2015, Huawei and Ericsson are testing 5G-related technologies in rural areas in northern Netherlands.
In July 2015, the METIS-II and 5GNORMA European projects were launched. The METIS-II project builds on the successful METIS project and will develop the overall 5G radio access network design and to provide the technical enablers needed for an efficient integration and use of the various 5G technologies and components currently developed. METIS-II will also provide the 5G collaboration framework within 5G-PPP for a common evaluation of 5G radio access network concepts and prepare concerted action towards regulatory and standardization bodies. On the other hand, the key objective of 5G NORMA is to develop a conceptually novel, adaptive and future-proof 5G mobile network architecture. The architecture is enabling unprecedented levels of network customizability, ensuring stringent performance, security, cost and energy requirements to be met; as well as providing an API-driven architectural openness, fuelling economic growth through over-the-top innovation. With 5G NORMA, leading players in the mobile ecosystem aim to underpin Europe’s leadership position in 5G.
Additionally, in July 2015, the European research project mmMAGIC was launched. The mmMAGIC project will develop new concepts for mobile radio access technology (RAT) for mmwave band deployment. This is a key component in the 5G multi-RAT ecosystem and will be used as a foundation for global standardization. The project will enable ultra fast mobile broadband services for mobile users, supporting UHD/3D streaming, immersive applications and ultra-responsive cloud services. A new radio interface, including novel network management functions and architecture components will be designed taking as guidance 5G PPP’s KPI and exploiting the use of novel adaptive and cooperative beam-forming and tracking techniques to address the specific challenges of mm-wave mobile propagation. The ambition of the project is to pave the way for a European head start in 5G standards and to strengthen European competitiveness. The consortium brings together major infrastructure vendors, major European operators, leading research institutes and universities, measurement equipment vendors and one SME. mmMAGIC is led and coordinated by Samsung. Ericsson acts as technical manager while Intel, Fraunhofer HHI, Nokia, Huawei and Samsung will each lead one of the five technical work packages of the project.
In July 2015, IMDEA Networks launched the Xhaul project, as part of the European H2020 5G Public-Private Partnership (5G PPP). Xhaul will develop an adaptive, sharable, cost-efficient 5G transport network solution integrating the fronthaul and backhaul segments of the network. This transport network will flexibly interconnect distributed 5G radio access and core network functions, hosted on in-network cloud nodes. Xhaul will greatly simplify network operations despite growing technological diversity. It will hence enable system-wide optimisation of Quality of Service (QoS) and energy usage as well as network-aware application development. The Xhaul consortium comprises 21 partners including leading telecom industry vendors, operators, IT companies, small and medium-sized enterprises and academic institutions.
In July 2015, the European 5G research project Flex5Gware was launched. The objective of Flex5Gware is to deliver highly reconfigurable hardware (HW) platforms together with HW-agnostic software (SW) platforms targeting both network elements and devices and taking into account increased capacity, reduced energy footprint, as well as scalability and modularity, to enable a smooth transition from 4G mobile wireless systems to 5G. This will enable that 5G HW/SW platforms can meet the requirements imposed by the anticipated exponential growth in mobile data traffic (1000 fold increase) together with the large diversity of applications (from low bit-rate/power for M2M to interactive and high resolution applications).
In July 2015, the SUPERFLUIDITY project, part of the European H2020 Public-Private Partnership (5G PPP) and led by CNIT, an Italian inter-university consortium, was started. The SUPERFLUIDITY consortium comprises telcos and IT players for a total of 18 partners. In physics, superfluidity is a state in which matter behaves like a fluid with zero viscosity. The SUPERFLUIDITY project aims at achieving superfluidity in the Internet: the ability to instantiate services on-the-fly, run them anywhere in the network (core, aggregation, edge) and shift them transparently to different locations. The project tackles crucial shortcomings in today’s networks: long provisioning times, with wasteful over-provisioning used to meet variable demand; reliance on rigid and cost-ineffective hardware devices; daunting complexity emerging from three forms of heterogeneity: heterogeneous traffic and sources; heterogeneous services and needs; and heterogeneous access technologies, with multi-vendor network components. SUPERFLUIDITY will provide a converged cloud-based 5G concept that will enable innovative use cases in the mobile edge, empower new business models, and reduce investment and operational costs.
In September 2016, China’s Ministry of Industry and Information Technology announced that the government-led 5G Phase-1 test of key wireless technologies for future 5G networks were completed with satisfactory results. The tests were carried out in 100 cities and involved seven companies – Datang Telecom, Ericsson, Huawei, Intel, Nokia Shanghai Bell, Samsung and ZTE. The next step in 5G technology development involving trials is under way, with planned commercial deployment in 2022 or 2023. In April 2017 Huawei announced that it jointly with Telenor conducted successful 5G tests with speeds up to 70 Gbit/s in a controlled lab environment in Norway. The E-band multi-user MIMO can provide a 20 Gbit/s speed rate for a single user. Working as a supplementary low-frequency band, the E-band improves the user experience of enhanced mobile broadband (eMBB).
(from Wikipedia)

发表评论

You must be logged in to post a comment.