CCIE职业发展系列典型案列分析之RIP偏移列表配置

案例：

说明：192.168.3.0/24,

          192.168.5.0/24,

          192.168.6.0/24

          都使用loopback 口模拟。

通过使用偏移列表限制RT1学习到   192.168.6.0/24  这条路由信息。

使用列表前的路由信息：

RT1#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

C    192.168.4.0/24 is directly connected, Serial1/0
R    192.168.5.0/24 [120/1] via 192.168.4.2, 00:00:16, Serial1/0
R    192.168.6.0/24 [120/1] via 192.168.4.2, 00:00:13, Serial1/0
C    192.168.3.0/24 is directly connected, Loopback0
RT1#sh ip route rip
R    192.168.5.0/24 [120/1] via 192.168.4.2, 00:00:20, Serial1/0
R    192.168.6.0/24 [120/1] via 192.168.4.2, 00:00:18, Serial1/0

可以看到RT1学习到192.168.6.0的路由。

解决方案：

RT1(config)#access-list 1 permit 192.168.6.0
RT1(config)#router rip
RT1(config-router)#offset-list 1 in 16 serial 1/0

配置完成后的路由信息

RT1#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static route
       o - ODR, P - periodic downloaded static route

Gateway of last resort is not set

C    192.168.4.0/24 is directly connected, Serial1/0
R    192.168.5.0/24 [120/1] via 192.168.4.2, 00:00:10, Serial1/0
C    192.168.3.0/24 is directly connected, Loopback0
RT1#sh ip route ri
RT1#sh ip route rip
R    192.168.5.0/24 [120/1] via 192.168.4.2, 00:00:12, Serial1/0

可以看到RT1的路由表中，已经没有192.168.6.0/24这条路由了。

扩展：

这是Debug的信息  debug ip rip

RT1#
*Mar  1 00:14:09.119: RIP: received v1 update from 192.168.4.2 on Serial1/0
*Mar  1 00:14:09.123:      192.168.5.0 in 1 hops
*Mar  1 00:14:09.127:      192.168.6.0 in 17 hops (inaccessible)
*Mar  1 00:14:15.199: RIP: sending v1 update to 255.255.255.255 via Loopback0 (192.168.3.1)
*Mar  1 00:14:15.203: RIP: build update entries
*Mar  1 00:14:15.203:   network 192.168.4.0 metric 1
*Mar  1 00:14:15.203:   network 192.168.5.0 metric 2
*Mar  1 00:14:20.835: RIP: sending v1 update to 255.255.255.255 via Serial1/0 (192.168.4.1)
*Mar  1 00:14:20.839: RIP: build update entries
*Mar  1 00:14:20.839:   network 192.168.3.0 metric 1
*Mar  1 00:14:38.703: RIP: received v1 update from 192.168.4.2 on Serial1/0
*Mar  1 00:14:38.707:      192.168.5.0 in 1 hops
*Mar  1 00:14:38.711:      192.168.6.0 in 17 hops (inaccessible)

上面序号2 ，3， 4 可以看出 从邻居RT2收到 192.168.5.0  1跳 ， 192.168.6.0 17跳（因为偏移列表指定了跳数进来为16.所以加上原来的1跳是17跳） 

序号2 ，12 看出  此时我们使用的还是默认的30s 更新。

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