diff --git a/d36-EIGRP.md b/d36-EIGRP.md index cc0d19f..1816531 100644 --- a/d36-EIGRP.md +++ b/d36-EIGRP.md @@ -1503,4 +1503,39 @@ D* 0.0.0.0/0 [90/2297856] via 150.1.1.1, 00:03:07, Serial0/0 **Split Horizon in EIGRP Networks** +前面已获悉水平分割是一项距离矢量协议的特性,该特性强制路由信息无法从接收到的接口再发送回去,这样做就阻止了路由信息重新通告到接收其的源处(Previously, you learned that split horizon is a Distance Vector protocol feature mandating that routing information cannot be sent back out of the same interface through which it was received. This prevents the re-advertising of information back to the source from which it was learned)。虽然这个特征是一种很好的阻止环回机制(a great loop prevention mechanism),但其也是一项明显的缺陷,特别是在星形网络中(especially in hub-and-spoke networks)。为更好地理解此特性的劣势,就要参考下面图36.14中的EIGRP星形网络: + +*图 36.14 -- EIGRP的水平分割* + +图36.14中的拓扑,演示了一个典型的星形网络,其中的总部路由器(router HQ)是中心路由器(the hub router), 路由器S1与S2则是分支路由器(the spoke router)。在帧中继广域网中,每台分支路由器都有着一个在部分网状拓扑(a partial-mesh topology)中的分支路由器与中心路由器之间,所提供的数据链路层连接标识(Data Link Connection Identifier 数据链接连接标识,这是个6位标识,表示正在进行的客户和服务器之间的连接。用于RFCOMM 层。On the Frame Relay WAN, each spoke router has a single DLCI provisioned between itself and the HQ router in a partial-mesh topology)。下面对这些路由器上的帧中继配置进行了检查: + +``` +HQ#show frame-relay map +Serial0/0 (up): ip 172.16.1.2 dlci 102(0x66,0x1860), static, + broadcast, + CISCO, status defined, active +Serial0/0 (up): ip 172.16.1.1 dlci 103(0x67,0x1870), static, + broadcast, + CISCO, status defined, active +``` + +``` +S1#show frame-relay map +Serial0/0 (up): ip 172.16.1.2 dlci 301(0x12D,0x48D0), static, + broadcast, + CISCO, status defined, active +Serial0/0 (up): ip 172.16.1.3 dlci 301(0x12D,0x48D0), static, + broadcast, + CISCO, status defined, active +``` + +``` +S2#show frame-relay map +Serial0/0 (up): ip 172.16.1.1 dlci 201(0xC9,0x3090), static, + broadcast, + CISCO, status defined, active +Serial0/0 (up): ip 172.16.1.3 dlci 201(0xC9,0x3090), static, + broadcast, + CISCO, status defined, active +``` diff --git a/images/3614.png b/images/3614.png new file mode 100644 index 0000000..f1e1168 Binary files /dev/null and b/images/3614.png differ