今天上課的時候有一個問題,詢問老師得到的結果和書上看到的不一樣,做個實驗驗證一下。
考慮一個拓撲:
3臺路由,4個網段,運行RIP v1協議,在R1上debug ip rip查看路由更新。
Router1#debug ip rip
RIP protocol debugging is on
*Mar 1 00:11:02.355: RIP: sending v1 update to 255.255.255.255 via FastEthernet1/0 (192.168.1.254)
*Mar 1 00:11:02.355: RIP: build update entries
*Mar 1 00:11:02.355: network 172.16.0.0 metric 1
*Mar 1 00:11:02.355: network 172.17.0.0 metric 2
*Mar 1 00:11:02.359: network 192.168.2.0 metric 3
*Mar 1 00:11:02.831: RIP: received v1 update from 172.16.0.2 on FastEthernet0/0
*Mar 1 00:11:02.831: 172.17.0.0 in 1 hops
*Mar 1 00:11:02.835: 192.168.2.0 in 2 hops
*Mar 1 00:11:08.403: RIP: sending v1 update to 255.255.255.255 via FastEthernet0/0 (172.16.0.1)
*Mar 1 00:11:08.403: RIP: build update entries
*Mar 1 00:11:08.403: network 192.168.1.0 metric 1
*Mar 1 00:11:29.791: RIP: received v1 update from 172.16.0.2 on FastEthernet0/0
*Mar 1 00:11:29.791: 172.17.0.0 in 1 hops
*Mar 1 00:11:29.795: 192.168.2.0 in 2 hops
從debug信息來看,RIP協議是在路由更新發送出去的時候就將跳數+1了,而不是收到的時候。