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【速搜问答】无线选路协议是什么

问答 admin 9个月前 (04-13) 152次浏览 已收录 0个评论

汉英对照:
Chinese-English Translation:

无线选路协议是基于表的路径矢量选路协议。网络上每一个节点维护一路径表、选路表、链路—成本表和消息转发列表。无线选路协议包括内部网关协议 RIP、OSPF 和外部网关协议 BGP。

Wireless routing protocol is a path vector routing protocol based on table. Each node in the network maintains a path table, routing table, link cost table and message forwarding list. Wireless routing protocol includes internal gateway protocol rip, OSPF and external Gateway Protocol BGP.

无线选路协议是基于表的路径矢量选路协议。网络上每一个节点维护一路径表、选路表、链路—成本表和消息转发列表。无线选路协议包括内部网关协议 RIP、OSPF 和外部网关协议 BGP。

Wireless routing protocol is a path vector routing protocol based on table. Each node in the network maintains a path table, routing table, link cost table and message forwarding list. Wireless routing protocol includes internal gateway protocol rip, OSPF and external Gateway Protocol BGP.

RIP 是一种基于距离向量的路由协议,以路由跳数作为计数单位的路由协议。适合用于比较小型的网络环境。

Rip is a routing protocol based on distance vector, which takes the number of hops as the count unit. It is suitable for small network environment.

OSPF(开放式最短路径优先)是一个内部网关协议(简称 IGP),用于在单一自治系统内决策路由。是对链路状态路由协议的一种实现,隶属内部网关协议(IGP)。

OSPF (open shortest path first) is an internal gateway protocol (IGP), which is used to make routing decisions in a single autonomous system. It is an implementation of link state routing protocol, which belongs to internal gateway protocol (IGP).

边界网关协议(BGP)是运行于 TCP 上的一种自治系统的路由协议。 BGP 是唯一一个用来处理像因特网大小的网络的协议,也是唯一能够妥善处理好不相关路由域间的多路连接的协议。

Border gateway protocol (BGP) is an autonomous routing protocol running on TCP. BGP is the only protocol used to deal with networks the size of the Internet, and it is also the only protocol that can properly handle multiple connections between unrelated routing domains.

无线选路协议的概念

The concept of wireless routing protocol

无线选路协议是基于表的路径矢量选路协议。网络上每一个节点维护一路径表、选路表、链路—成本表和消息转发列表。

Wireless routing protocol is a path vector routing protocol based on table. Each node in the network maintains a path table, routing table, link cost table and message forwarding list.

无线选路协议包括内部网关协议 RIP、OSPF 和外部网关协议 BGP。

Wireless routing protocol includes internal gateway protocol rip, OSPF and external Gateway Protocol BGP.

RIP 是一种基于距离向量的路由协议,以路由跳数作为计数单位的路由协议。适合用于比较小型的网络环境。

Rip is a routing protocol based on distance vector, which takes the number of hops as the count unit. It is suitable for small network environment.

OSPF(Open Shortest Path First 开放式最短路径优先)是一个内部网关协议(Interior Gateway Protocol,简称 IGP),用于在单一自治系统(autonomous system,AS)内决策路由。是对链路状态路由协议的一种实现,隶属内部网关协议(IGP),故运作于自治系统内部。著名的迪克斯加算法(Dijkstra)被用来计算最短路径树。OSPF 分为 OSPFv2 和 OSPFv3 两个版本,其中 OSPFv2 用在 IPv4 网络,OSPFv3 用在 IPv6 网络。OSPFv2 是由 RFC 2328 定义的,OSPFv3 是由 RFC 5340 定义的。与 RIP 相比,OSPF 是链路状态协议,而 RIP 是距离矢量协议。

OSPF (open shortest path first) is an internal gateway protocol (IGP), which is used to make routing decisions in an autonomous system (as). It is an implementation of link state routing protocol. It belongs to internal gateway protocol (IGP), so it operates in autonomous system. The famous Dijkstra algorithm is used to calculate the shortest path tree. OSPF is divided into two versions: ospfv2 and OSPFv3. Ospfv2 is used in IPv4 network and OSPFv3 is used in IPv6 network. Ospfv2 is defined by RFC 2328 and OSPFv3 is defined by RFC 5340. Compared with rip, OSPF is a link state protocol, while Rip is a distance vector protocol.

边界网关协议(BGP)是运行于 TCP 上的一种自治系统的路由协议。 BGP 是唯一一个用来处理像因特网大小的网络的协议,也是唯一能够妥善处理好不相关路由域间的多路连接的协议。 BGP 构建在 EGP 的经验之上。 BGP 系统的主要功能是和其他的 BGP 系统交换网络可达信息。网络可达信息包括列出的自治系统(AS)的信息。这些信息有效地构造了 AS 互联的拓朴图并由此清除了路由环路,同时在 AS 级别上可实施策略决策。

Border gateway protocol (BGP) is an autonomous routing protocol running on TCP. BGP is the only protocol used to deal with networks the size of the Internet, and it is also the only protocol that can properly handle multiple connections between unrelated routing domains. BGP is built on the experience of EGP. The main function of BGP system is to exchange network reachable information with other BGP systems. Network reachability information includes information of listed autonomous system (as). This information effectively constructs the topology of as interconnection and eliminates the routing loops. At the same time, policy decisions can be implemented at the as level.

无线选路协议的工作原理

Working principle of wireless routing protocol

无线选路协议的产生

Generation of wireless routing protocol

IETF 为了满足建造越来越大基于 IP 网络的需要,形成了一个工作组,专门用于开发开放式的链路状态路由协议,以便用在大型、异构的 I P 网络中。新的路由协议已经取得一些成功的一系列私人的、和生产商相关的、最短路径优先(SPF )路由协议为基础, 在市场上广泛使用。包括 OSPF 在内,所有的 S P F 路由协议基于一个数学算法—Dijkstra 算法。这个算法能使路由选择基于链路状态,而不是距离向量。OSPF 由 IETF 在 20 世纪 80 年代末期开发,OSPF 是 SPF 类路由协议中的开放式版本。最初的 OSPF 规范体如今 RFC1131 中。这个第 1 版( OSPF 版本 1 )很快被进行了重大改进的版本所代替,这个新版本体如今 RFC1247 文档中。RFC 1247OSPF 称为 OSPF 版本 2 是为了明确指出其在稳定性和功能性方面的实质性改进。这个 OSPF 版本有许多更新文档,每一个更新都是对开放标准的精心改进。接下来的一些规范出如今 RFC 1583、2178 和 2328 中。OSPF 版本 2 的最新版体如今 RFC 2328 中。最新版只会和由 RFC 2138、1583 和 1247 所规范的版本进行互操作。

In order to meet the needs of building larger and larger IP based networks, IETF has formed a working group to develop open link state routing protocols for large and heterogeneous IP networks. The new routing protocol has achieved some success, which is based on a series of private, manufacturer related, shortest path first (SPF) routing protocols and is widely used in the market. All SPF routing protocols, including OSPF, are based on a mathematical algorithm Dijkstra algorithm. This algorithm can make routing based on link state rather than distance vector. OSPF was developed by IETF in the late 1980s. OSPF is an open version of SPF routing protocol. The original OSPF specification is now in rfc1131. This version 1 (OSPF version 1) was quickly replaced by a significantly improved version, which is now in the rfc1247 document. RFC 1247 OSPF is called OSPF version 2 to clearly point out its substantial improvements in stability and functionality. This version of OSPF has many updated documents, each of which is an elaborate improvement on open standards. Some of the following specifications are now in RFC 1583, 2178, and 2328. The latest version of OSPF version 2 is now in RFC 2328. The latest version will only interoperate with the version specified by RFC 2138, 1583 and 1247.

链路是路由器接口的另一种说法,因此 OSPF 也称为接口状态路由协议。OSPF 通过路由器之间通告网络接口的状态来建立链路状态数据库,生成最短路径树,每个 OSPF 路由器使用这些最短路径构造路由表。

Link is another term for router interface, so OSPF is also called interface state routing protocol. OSPF establishes the link state database by notifying the state of the network interface between routers, and generates the shortest path tree. Each OSPF router uses these shortest paths to construct the routing table.

OSPF 路由协议是一种典型的链路状态(Link-state)的路由协议,一般用于同一个路由域内。在这里,路由域是指一个自治系统(Autonomous System),即 AS,它是指一组通过统一的路由政策或路由协议互相交换路由信息的网络。在这个 AS 中,所有的 OSPF 路由器都维护一个相同的描述这个 AS 结构的数据库,该数据库中存放的是路由域中相应链路的状态信息,OSPF 路由器正是通过这个数据库计算出其 OSPF 路由表的。

OSPF routing protocol is a typical link state routing protocol, which is generally used in the same routing domain. Here, routing domain refers to an autonomous system (as), which refers to a group of networks that exchange routing information through a unified routing policy or routing protocol. In this as, all OSPF routers maintain the same database describing the as structure, which stores the state information of the corresponding links in the routing domain. It is through this database that OSPF routers calculate their OSPF routing tables.

作为一种链路状态的路由协议,OSPF 将链路状态组播数据 LSA(Link State Advertisement)传送给在某一区域内的所有路由器,这一点与距离矢量路由协议不同。运行距离矢量路由协议的路由器是将部分或全部的路由表传递给与其相邻的路由器。

As a link state routing protocol, OSPF transmits link state multicast data LSA (link state advertisement) to all routers in a certain area, which is different from distance vector routing protocol. The router running distance vector routing protocol passes part or all of the routing tables to its neighboring routers.

BGP 用于在不同的自治系统(AS)之间交换路由信息。当两个 AS 需要交换路由信息时,每个 AS 都必须指定一个运行 BGP 的节点,来代表 AS 与其他的 AS 交换路由信息。这个节点可以是一个主机。但通常是路由器来执行 BGP。两个 AS 中利用 BGP 交换信息的路由器也被称为边界网关(Border Gateway)或边界路由器(Border Router) 。

BGP is used to exchange routing information between different autonomous systems (as). When two as need to exchange routing information, each as must specify a node running BGP to exchange routing information with other as on behalf of as. This node can be a host. But it’s usually the router that performs BGP. The router that uses BGP to exchange information in two as is also called border gateway or border router.

由于可能与不同的 AS 相连,在一个 AS 内部可能存在多个运行 BGP 的边界路由器。同一个自治系统(AS)中的两个或多个对等实体之间运行的 BGP 被称为 IBGP(Internal/Interior BGP)。归属不同的 AS 的对等实体之间运行的 BGP 称为 EBGP (External/Exterior BGP)。在 AS 边界上与其他 AS 交换信息的路由器被称作边界路由器(border/edge router)。在互联网操作系统(Cisco IOS)中,IBGP 通告的路由的距离为 200,优先级比 EBGP 和任何内部网关协议(IGP)通告的路由都低。其他的路由器实现中,优先级顺序也是 EBGP 高于 IGP,而 IGP 又高于 IBGP。

As it may be connected with different as, there may be multiple border routers running BGP in one as. The BGP running between two or more peer entities in the same autonomous system (as) is called iBGP (internal / internal BGP). The BGP running between peers belonging to different as is called ebgp (external / external BGP). The router that exchanges information with other as on the as boundary is called border / edge router. In the Internet operating system (Cisco IOS), the distance of routes advertised by iBGP is 200, and the priority is lower than that advertised by ebgp and any internal gateway protocol (IGP). In other router implementations, the priority order of ebgp is higher than IGP, and IGP is higher than iBGP.

BGP 属于外部网关路由协议,可以实现自治系统间无环路的域间路由。BGP 是沟通 Internet 广域网的主用路由协议,例如不同省份、不同国家之间的路由大多要依靠 BGP 协议。BGP 可分为 IBGP(Internal BGP)和 EBGP(External BGP)。BGP 的邻居关系(或称通信对端/对等实体)是通过人工配置实现的,对等实体之间通过 TCP(端口 179)会话交互数据。BGP 路由器会周期地发送 19 字节的保持存活 keep-alive 消息来维护连接(默认周期为 30 秒)。在路由协议中,只有 BGP 使用 TCP 作为传输层协议。

BGP is an external gateway routing protocol, which can realize loop free inter domain routing between autonomous systems. BGP is the main routing protocol for Internet wide area network. For example, the routing between different provinces and countries mostly depends on BGP. BGP can be divided into iBGP (internal BGP) and ebgp (external BGP). The neighbor relationship (or peer / peer entity) of BGP is realized by manual configuration. Peer entities interact with each other through TCP (Port 179) session. The BGP router periodically sends a 19 byte keep alive message to maintain the connection (the default period is 30 seconds). In the routing protocol, only BGP uses TCP as the transport layer protocol.

无线选路协议的基本原理

The basic principle of wireless routing protocol

因为 OSPF 路由器之间会将所有的链路状态(LSA)相互交换,毫不保留,当网络规模达到一定程度时,LSA 将形成一个庞大的数据库,势必会给 OSPF 计算带来巨大的压力;为了能够降低 OSPF 计算的复杂程度,缓存计算压力,OSPF 采用分区域计算,将网络中所有 OSPF 路由器划分成不同的区域,每个区域负责各自区域精确的 LSA 传递与路由计算,然后再将一个区域的 LSA 简化和汇总之后转发到另外一个区域,这样一来,在区域内部,拥有网络精确的 LSA,而在不同区域,则传递简化的 LSA。区域的划分为了能够尽量设计成无环网络,所以采用了 Hub-Spoke 的拓朴架构,也就是采用核心与分支的拓朴,如下图:

Because OSPF routers will exchange all link states (LSAS) with each other without reservation, when the network scale reaches a certain level, LSA will form a huge database, which is bound to bring great pressure to OSPF calculation. In order to reduce the complexity of OSPF calculation and cache the calculation pressure, OSPF adopts the partition calculation, and all ospfs in the network will be saved The router is divided into different regions. Each region is responsible for the accurate LSA delivery and routing calculation of its own region. Then the LSA of one region is simplified and summarized, and then it is forwarded to another region. In this way, in the region, there is a network accurate LSA, while in different regions, the simplified LSA is delivered. In order to design the area as an acyclic network as far as possible, the hub spoke topology is adopted, that is, the core and branch topology is adopted, as shown in the following figure:

区域的命名可以采用整数数字,如 1、2、3、4,也可以采用 IP 地址的形式,0.0.0.1、0.0.0.2,因为采用了 Hub-Spoke 的架构,所以必须定义出一个核心,然后其它部分都与核心相连,OSPF 的区域 0 就是所有区域的核心,称为 BackBone 区域(骨干区域),而其它区域称为 Normal 区域(常规区域),在理论上,所有的常规区域应该直接和骨干区域相连,常规区域只能和骨干区域交换 LSA,常规区域与常规区域之间即使直连也无法互换 LSA,如上图中 Area 1、Area 2、Area 3、Area 4 只能和 Area 0 互换 LSA,然后再由 Area 0 转发,Area 0 就像是一个中转站,两个常规区域需要交换 LSA,只能先交给 Area 0,再由 Area 0 转发,而常规区域之间无法互相转发。

The area can be named in integer numbers, such as 1, 2, 3, 4, or in the form of IP address, 0.0.0.1, 0.0.0.2. Because the hub spoke architecture is adopted, a core must be defined, and then other parts are connected with the core. OSPF area 0 is the core of all areas, which is called backbone area, while other areas are called backbone area In theory, all the conventional areas should be directly connected with the backbone area. The conventional area can only exchange LSA with the backbone area. Even if the conventional area is directly connected with the conventional area, the LSA cannot be exchanged. As shown in the figure above, area 1, area 2, area 3 and area 4 can only exchange LSA with area 0, and then they can be forwarded by area 0, and area 0 can exchange LSA Just like a transfer station, two conventional areas need to exchange LSA, which can only be delivered to area 0 first and then forwarded by area 0, while conventional areas cannot forward each other.

BGP/MPLS VPN 以隧道的方式解决了在公网中传送私网数据的问题,但传统的 BGP/MPLS VPN 架构要求每个 VPN 实例单独使用一个 CE 与 PE 相连。

BGP / MPLS VPN solves the problem of private network data transmission in public network by means of tunnel, but the traditional BGP / MPLS VPN architecture requires each VPN instance to use a separate CE to connect with PE.

随着用户业务的不断细化和安全需求的提高,很多情况下一个私有网络内的用户需要划分成多个 VPN,不同 VPN 用户间的业务需要完全隔离。此时,为每个 VPN 单独配置一台 CE 将加大用户的设备开支和维护成本;而多个 VPN 共用一台 CE,使用同一个路由表项,又无法保证数据的安全性。使用 MCE 功能,可以有效解决多 VPN 网络带来的用户数据安全与网络成本之间的矛盾,它使用 CE 设备本身的 VLAN 接口编号与网络内的 VPN 进行绑定,并为每个 VPN 创建和维护独立的路由转发表(Multi-VRF)。这样不但能够隔离私网内不同 VPN 的报文转发路径,而且通过与 PE 间的配合,也能够将每个 VPN 的路由正确发布至对端 PE,保证 VPN 报文在公网内的传输。

With the continuous refinement of user services and the improvement of security requirements, in many cases, users in a private network need to be divided into multiple VPNs, and the services between different VPN users need to be completely isolated. At this time, configuring a CE for each VPN will increase the user’s equipment expenses and maintenance costs; while multiple VPNs share a CE and use the same routing table entry, it can not guarantee the data security. Using MCE function can effectively solve the contradiction between user data security and network cost brought by multi VPN network. It uses VLAN interface number of CE device to bind VPN in the network, and creates and maintains independent route forwarding table (multi VRF) for each VPN. In this way, it can not only isolate the packet forwarding paths of different VPNs in the private network, but also correctly publish the route of each VPN to the peer PE through the cooperation with PE, so as to ensure the transmission of VPN packets in the public network.


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