DHCP的配置综合实验

这个是拓扑   最上面的那个路由器模拟DHCP服务器，本实验重点是DHCP的配置。  之前我在51CTO上查了下相关实验，关于ip helper-address与vlan一起的实验 不多，于是我自己练习了下  之间遇到了一些问题，下面我来给大家简单讲解下
先贴配置
R5#
%SYS-5-CONFIG_I: Configured from console by console
sh run
Building configuration...
Current configuration : 803 bytes
!
version 12.4
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname R5
!
!
!
!
ip dhcp excluded-address 192.168.10.1
ip dhcp excluded-address 192.168.20.1
!
ip dhcp pool 10
network 192.168.10.0 255.255.255.0
default-router 192.168.10.1
ip dhcp pool 20
network 192.168.20.0 255.255.255.0
default-router 192.168.20.1
!
!
!
!
!
!
!
!
!
!
!
!
!
interface FastEthernet0/0
ip address 192.168.12.1 255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
no ip address
duplex auto
speed auto
shutdown
!
interface Vlan1
no ip address
shutdown
!
router rip
version 2
network 192.168.12.0
no auto-summary
!
ip classless
ip route 0.0.0.0 0.0.0.0 FastEthernet0/0
!
!
!
!
!
!
!
line con 0
R1#sh
% Incomplete command.
R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#no ip route 0.0.0.0 0.0.0.0 fa0/0
R1(config)#^Z
R1#
%SYS-5-CONFIG_I: Configured from console by console
sh run
Building configuration...
Current configuration : 761 bytes
!
version 12.4
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname R1
!
!
!
!
ip dhcp excluded-address 192.168.10.1
ip dhcp excluded-address 192.168.20.1
!
ip dhcp pool 10
network 192.168.10.0 255.255.255.0
default-router 192.168.10.1
ip dhcp pool 20
network 192.168.20.0 255.255.255.0
default-router 192.168.20.1
!
!
!
!
!
!
!
!
!
!
!
!
!
interface FastEthernet0/0
ip address 192.168.12.1 255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
no ip address
duplex auto
speed auto
shutdown
!
interface Vlan1
no ip address
shutdown
!
router rip
version 2
network 192.168.12.0
no auto-summary
!
ip classless
!
!
!
!
!
!
!
line con 0
line vty 0 4
login
!
!
!
end
 
 
 
R6
Router#
%SYS-5-CONFIG_I: Configured from console by console
sh run
Building configuration...
Current configuration : 835 bytes
!
version 12.4
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname Router
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!
interface FastEthernet0/0
ip address 192.168.12.2 255.255.255.0
duplex auto
speed auto
!
interface FastEthernet0/1
no ip address
duplex auto
speed auto
!
interface FastEthernet0/1.10
encapsulation dot1Q 10
ip address 192.168.10.1 255.255.255.0
ip helper-address 192.168.12.1
!
interface FastEthernet0/1.20
encapsulation dot1Q 20
ip address 192.168.20.1 255.255.255.0
ip helper-address 192.168.12.1
!
interface Vlan1
no ip address
shutdown
!
router rip
version 2
network 192.168.10.0
network 192.168.12.0
network 192.168.20.0
network 192.168.23.0
no auto-summary
!
ip classless
!
!
!
!
!
!
!
line con 0
line vty 0 4
login
!
!
!
end
 
 
 
 
SW
Switch#sh run
Building configuration...
Current configuration : 1202 bytes
!
version 12.2
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname Switch
!
!
!
interface FastEthernet0/1
switchport mode trunk
!
interface FastEthernet0/2
switchport access vlan 10
switchport mode access
!
interface FastEthernet0/3
switchport access vlan 20
switchport mode access
!
interface FastEthernet0/4
!
interface FastEthernet0/5
!
interface FastEthernet0/6
!
interface FastEthernet0/7
!
interface FastEthernet0/8
!
interface FastEthernet0/9
!
interface FastEthernet0/10
!
interface FastEthernet0/11
!
interface FastEthernet0/12
!
interface FastEthernet0/13
!
interface FastEthernet0/14
!
interface FastEthernet0/15
!
interface FastEthernet0/16
!
interface FastEthernet0/17
!
interface FastEthernet0/18
!
interface FastEthernet0/19
!
interface FastEthernet0/20
!
interface FastEthernet0/21
!
interface FastEthernet0/22
!
interface FastEthernet0/23
!
interface FastEthernet0/24
!
interface GigabitEthernet1/1
!
interface GigabitEthernet1/2
!
interface Vlan1
no ip address
shutdown
!
interface Vlan10
no ip address
!
interface Vlan20
no ip address
!
!
line con 0
!
line vty 0 4
login
line vty 5 15
login
!
!
end
 
 
 



遇到的困难都是PC没能获取到IP  原因如下
1，没有起路由协议   至于为什么要用到路由协议 这个与ip helper add 原理有关（
配置了ip helper-address命令之后的路由器在中继DHCP请求时的工作过程如下:
a,DHCP客户端发送请求，由于没有ip地址，所以自己的源IP地址为0.0.0.0，而且也不知道目的DHCP服务器的地址，所以为广播255.255.255.255。该数据报中当然还包含其他信息，比如二层的信息，源mac地址，和目的mac地址FFFFFFFFFFFF。
b，当路由器接收到该数据报的时候，他就用自己的接口地址（接收到数据报的接口）来取代源地址0.0.0.0，并且用ip help-address 命令中指定的地址
）
2，没有配ip helper add   我一开始是在R6上的fa0/1配的这个命令 但是没有效果   于是进到子接口配这个命令在获取到Ip
 
如果大家有啥问题 可以留言