配置步骤：
1、定义密钥链名称
key chain 密钥链名称
2、在密钥链上定义密钥(可以定义多个密钥)
key 1
key-string 密码
3、在指定接口上应用密钥链
int f0/0
ip rip authentication key-chain 密钥链名称
ip rip authentication mode md5
4、在指定接口上使用的认证类型是明文还是MD5
int f0/0
ip rip authentication mode md5
排错命令：
debug ip rip
show ip rip datebase
R1#show ip rip database
1.0.0.0/8 auto-summary
1.1.1.0/24 directly connected, Loopback0
2.0.0.0/8 auto-summary
2.0.0.0/8
[1] via 192.168.1.2, 00:00:06, FastEthernet0/0
192.168.1.0/24 auto-summary
192.168.1.0/30 directly connected, FastEthernet0/0
*Mar 1 00:16:09.651: RIP: sending v2 update to 224.0.0.9 via FastEthernet0/0 (192.168.1.1)
*Mar 1 00:16:09.651: RIP: build update entries
*Mar 1 00:16:09.651: 1.0.0.0/8 via 0.0.0.0, metric 1, tag 0
*Mar 1 00:16:10.311: RIP: sending v2 update to 224.0.0.9 via Loopback0 (1.1.1.1)
*Mar 1 00:16:10.311: RIP: build update entries
*Mar 1 00:16:10.311: 2.0.0.0/8 via 0.0.0.0, metric 1, tag 0
*Mar 1 00:16:10.315: 192.168.1.0/24 via 0.0.0.0, metric 1, tag 0
*Mar 1 00:16:10.319: RIP: ignored v2 packet from 1.1.1.1 (sourced from one of our addresses)
R1#
*Mar 1 00:16:19.731: RIP: received packet with MD5 authentication
*Mar 1 00:16:19.731: RIP: received v2 update from 192.168.1.2 on FastEthernet0/0
*Mar 1 00:16:19.735: 2.0.0.0/8 via 0.0.0.0 in 1 hops
