有类无类路由协议的区别.doc

有类路由协议与无类路由协议(一)有类路由协议代表：RIPv1、IGRP = RIPv1和IGRP都是距离矢量有类别的路由选择协议特点： 1、在发送的update包中不携带子网掩码信息2、在主类边界路由器执行自动汇总，并且该自动汇总无法人工关闭3、不支持VLSM，即同一个主网络下的子网若掩码长度不一致则会出现子网丢弃的 情况主类边界路由器：如果某台Router上配置了多个网段，其中某些网段的信息必段通过某一个特定的网段向其它Router进行通告，而这个特定的网段与其它网段分属于不同的主类网络，那么这台Router就是主类边界路由器实验： 图 1-13分析：R1#debug ip rip*Jul 29 20:25:54.239: RIP: sending v1 update to 255.255.255.255 via Serial1/0 (10.0.0.1)*Jul 29 20:25:54.239: RIP: build update entries*Jul 29 20:25:54.239: subnet 10.0.1.0 metric 1*Jul 29 20:25:54.239: network 11.0.0.0 metric 1当RIP把R1的路由表中的条目封装到update包中，并且从S1/0接口发出去时RIP要对路由表中的条目进行筛选汇总，此筛选汇总的规则如下：检查条目是否与发送端口属于同一主网1）.若否，则该条目自动被汇总成主类网络，然后封装到update包中（不带掩码）2）.若是，继续检查条目是否与发送接口的掩码长度一致 a.是，发送该条目（不汇总，不带掩码）b.否，直接忽略R2# debug ip rip*Jul 29 20:27:31.151: RIP: received v1 update from 10.0.0.1 on Serial1/1*Jul 29 20:27:31.151: 10.0.1.0 in 1 hops*Jul 29 20:27:31.155: 11.0.0.0 in 1 hopsR2#sh ip routeGateway of last resort is not set 172.16.0.0/24 is subnetted, 1 subnetsC 172.16.0.0 is directly connected, Serial1/0 10.0.0.0/24 is subnetted, 2 subnetsC 10.0.0.0 is directly connected, Serial1/1R 10.0.1.0 120/1 via 10.0.0.1, 00:00:08, Serial1/1R 11.0.0.0/8 120/1 via 10.0.0.1, 00:00:08, Serial1/1可以看到R2己经通过RIPv1从R1哪里学习到了两条路由条目，并且还有掩码，该掩码信息是如何产生的？当R2接受到从R1哪里传来的两条路由更新（这两条路由更新是不携带子网掩码这点已经毋庸置疑）并把它放到路由表中之前要做一些处理，该处理的规则如下：将接收到的路由条目和接收接口的网络地址进行比较，判断是否处于同一主网络1）.处于同一主网络，直接将接收接口的掩码赋予该条目2）.不处于同一主类网络，首先查看路由表中是否存在该主网络的任一子网 a .不存在，赋予该条目一个有类掩码，同时写入路由表 b.存在，忽略该路由条目，直接丢弃R2#debug ip rip*Jul 29 21:21:53.771: RIP: sending v1 update to 255.255.255.255 via Serial1/0 (172.16.0.1)*Jul 29 21:21:53.771: RIP: build update entries*Jul 29 21:21:53.771: network 10.0.0.0 metric 1 *Jul 29 21:21:53.775: network 11.0.0.0 metric 2R3#sh ip routeGateway of last resort is not set 172.16.0.0/24 is subnetted, 1 subnetsC 172.16.0.0 is directly connected, Serial1/1R 10.0.0.0/8 120/1 via 172.16.0.1, 00:00:25, Serial1/1R 11.0.0.0/8 120/2 via 172.16.0.1, 00:00:25, Serial1/1R2#ping 10.0.2.1Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 10.0.2.1, timeout is 2 seconds:.Success rate is 0 percent (0/5)R3#ping 10.0.2.1Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 10.0.2.1, timeout is 2 seconds:U.U.U R2给R3返回的目标不可达消息Success rate is 0 percent (0/5)现在我们在R2增加一个LOOPBACK 0：11.11.11.11/24R2#sh ip routeGateway of last resort is not set 172.16.0.0/24 is subnetted, 1 subnetsC 172.16.0.0 is directly connected, Serial1/0 10.0.0.0/24 is subnetted, 2 subnetsC 10.0.0.0 is directly connected, Serial1/1R 10.0.1.0 120/1 via 10.0.0.1, 00:00:01, Serial1/1 11.0.0.0/8 is variably subnetted, 2 subnets, 2 masksC 11.11.11.0/24 is directly connected, Loopback0R 11.0.0.0/8 120/1 via 10.0.0.1, 00:00:44, Serial1/1 当R2从R1哪里接受到该路由条目时会直接丢弃，原因关于接受条目更新规则中有阐述当我们等到00：03：05时R 11.0.0.0/8 is possibly down, routing via 10.0.0.1, Serial1/1当我们等到00：04：00时直接从路由表中被删除0-30s:更新计时器31-180s:无效计时器180s-240s:保持失效计时器240s之后:刷新计时器当然我们可以直接用R2#clear ip route * 会让RIP产生触发式的更新 重新计算路由表R3#sh ip routeGateway of last resort is not set 172.16.0.0/24 is subnetted, 1 subnetsC 172.16.0.0 is directly connected, Serial1/1R 10.0.0.0/8 120/1 via 172.16.0.1, 00:00:00, Serial1/1R2(config)#router rip R2(config-router)#net 11.0.0.0R3#sh ip routeGateway of last resort is not set 172.16.0.0/24 is subnetted, 1 subnetsC 172.16.0.0 is directly connected, Serial1/1R 10.0.0.0/8 120/1 via 172.16.0.1, 00:00:12, Serial1/1R 11.0.0.0/8 120/1 via 172.16.0.1, 00:00:03, Serial1/1(二)无类路由协议代表：RIPV2 EIGRP OSPF ISIS BGPV4特点：1、在发送的update包中携带子网掩码信息2、部分无类协议（如：RIPV2 EIGRP）在主类边界路由器执行自动汇总功能是打开 的，并且该自动汇总可以人工关闭 3、支持VLSM，即同一个主网络下的子网若掩码长度不一致不会出现子网丢弃实验： 图 1-14先shut掉R2的lo0，全局配置RIPV1，R2路由表显示如下：R2#sh ip routeGateway of last resort is not setC 192.168.12.0/24 is directly connected, Serial1/1R 172.16.0.0/16 120/1 via 192.168.23.2, 00:00:26, Serial1/0120/1 via 192.168.12.1, 00:00:15, Serial1/1 =此时R2对左右两边“半信半疑”C 192.168.23.0/24 is directly connected, Serial1/0然后，激活R2的lo0，R2路由表如下：R2#sh ip routeGateway of last resort is not setC 192.168.12.0/24 is directly connected, Serial1/1 172.16.0.0/24 is subnetted, 1 subnetsC 172.16.20.0 is directly connected, Loopback0 =此时R2“只信自己”C 192.168.23.0/24 is directly connected, Serial1/0接着，把RIPV1升级到V2R2#sh ip routeGateway of last resort is not setC 192.168.12.0/24 is directly connected, Serial1/1 172.16.0.0/16 is variably subnetted, 2 subnets, 2 masksC 172.16.20.0/24 is directly connected, Loopback0R 172.16.0.0/16 120/1 via 192.168.23.2, 00:00:02, Serial1/0 120/1 via 192.168.12.1, 00:00:02, Serial1/1 =此时R2“集思广益”C 192.168.23.0/24 is directly connected, Serial1/0最后，no auto-summaryR2#clear ip route *R2#sh ip routeGateway of last resort is not setC 192.168.12.0/24 is directly connected, Serial1/1 172.16.0.0/2