cisco路由器基本实验之五配置Loopback接口进行远程登录（Boson NetSim）-阿里云开发者社区

先说点题外话，本来这两天是没时间来更新博客了的，但是事情出了点变化，使得我又有时间上网了，上网当然要到博客里面去逛逛了，没想到收到一封来自51cto的短信，说我的博客已经被评为推荐博客了，呵呵，真的很高兴能得到这样的荣誉，51cto让我感受到了学习的乐趣和写博客的动力（之前在csdn很没动力），更重要的是，能和这么多的网络技术爱好者共同学习，实在是一件很美妙的事情。感谢51cto。

最近我的这几篇关于cisco基础实验的文章都有幸得到了推荐，从网友的回复看，大多数网友还是支持我的，虽然我的文章对一部分博友来说很初级，但他们都没有说，相反还得到了他们的多次指点，真的很谢谢他们。当然我相信，我不会永远做初级的实验的，我是按照进度来循序渐进的进行的，总会做到高级一点的实验的，呵呵，当然，今天的实验应该还算初级的，呵呵。下面看实验。

实验开始前先说说Loopback接口，它是应用最为广泛的一种虚接口（即是接口不会依赖物理接口，接口的状态永远是UP的），网管完成网络规划之后，为了方便管理，会为每一台路由器创建一个loopback 接口，并在该接口上单独指定一个IP 地址作为管理地址，管理员会使用该地址对路由器远程登录（telnet）。因此学习它的配置还是有一定的意义的。

拓扑图如上所示，今天的实验通过show 的方式来展现，一来比较简短，二来比较易于察看，一目了然。

1.1 在r1上show run：

r1#show run
Building configuration...

!
Version 12.1
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname r1
!
!
!
ip subnet-zero
!
!
!
!
!
!
!
!
!
!
interface Loopback
ip address 10.1.1.1 255.255.255.0
no ip directed broadcast
!
interface Serial0
ip address 192.168.2.1 255.255.255.0
no ip directed-broadcast
clock rate 64000
!
interface Ethernet0
ip address 192.168.1.2 255.255.255.0
no ip directed-broadcast
!
!
router rip
network 192.168.1.0
network 192.168.2.0
network 10.0.0.0 //我的loopback接口的IP地址为10.1.1.1
!
ip classless
no ip http server
!
!
!
line con 0
transport input none
line aux 0
line vty 0 4 /启用了vty线路方可进行telnet
login
password cisco
!
no scheduler allocate
end

1.2在r1上show ip route

r1# show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
       U - per-user static route

Gateway of last resort is not set

     192.168.1.0/24 is subnetted, 1 subnets
C       192.168.1.0 is directly connected, Ethernet0
     10.0.0.0/24 is subnetted, 1 subnets
C       10.1.1.0 is directly connected, Loopback
     192.168.2.0/24 is subnetted, 1 subnets
C       192.168.2.0 is directly connected, Serial0
     192.168.3.0/24 is subnetted, 1 subnets
R       192.168.3.0 [120/1] via 192.168.2.2, 00:01:25, Serial0         //这个英文比较简单，应该看得懂

1.3 在r1上show ip pro

r1#show ip pro
Routing Protocol is "rip"
Sending updates every 30 seconds, next due in 7 seconds
Invalid after 180 seconds, hold down 180, flushed after 240     //从这句可以得知：该配置采用rip协议，路由器每隔30s发出更新信息，（next due in 7 seconds？），超过180s未收到路由更新则认为该路由无效，如果经过240s还没收到更新信息，这该路由信息将会从路由表中删除。
Outgoing update filter list for all interfaces is
Incoming update filter list for all interfaces is
Redistributing:   rip
Default version control: send version 1, receive any version
    Interface        Send Recv   Key-chain
    Serial0            1    1 2
    Ethernet0          1    1 2
Routing for Networks:
    192.168.1.0
    192.168.2.0
    10.0.0.0
Routing Information Sources:
    192.168.2.2           120      00:00:09
Distance: (default is 120)       //rip的管理距离默认为120，该值越小越好

21.在r2上show run：

r2#show run
Building configuration...

!
Version 12.1
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname r2
!
!
!
ip subnet-zero
!
!
!
!
!
!
!
!
!
!
interface Serial0
ip address 192.168.2.2 255.255.255.0
no ip directed-broadcast
!
interface Ethernet0
ip address 192.168.3.1 255.255.255.0
no ip directed-broadcast
!
!
router rip
network 192.168.3.0
network 192.168.2.0
!
ip classless
no ip http server
!
!
!
line con 0
transport input none
line aux 0
line vty 0 4
!
no scheduler allocate
end

2.2在r2上show ip route

r2#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate default
       U - per-user static route

Gateway of last resort is not set

     192.168.2.0/24 is subnetted, 1 subnets
C       192.168.2.0 is directly connected, Serial0
     192.168.3.0/24 is subnetted, 1 subnets
C       192.168.3.0 is directly connected, Ethernet0
     192.168.1.0/24 is subnetted, 1 subnets
R       192.168.1.0 [120/1] via 192.168.2.1, 00:08:16, Serial0
     10.0.0.0/24 is subnetted, 1 subnets
R       10.1.1.0 [120/1] via 192.168.2.1, 00:02:14, Serial0

2.3 在r2上show ip pro

r2#show ip pro
Routing Protocol is "rip"
Sending updates every 30 seconds, next due in 4 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Outgoing update filter list for all interfaces is
Incoming update filter list for all interfaces is
Redistributing:   rip
Default version control: send version 1, receive any version
    Interface        Send Recv   Key-chain
    Serial0            1    1 2
    Ethernet0          1    1 2
Routing for Networks:
    192.168.3.0
    192.168.2.0
Routing Information Sources:
    192.168.2.1           120      00:00:03
Distance: (default is 120) //意思同r1中的意思