思科三层交换机实现不同VLAN之间的DHCP通信
vlan10:192.168.10.0 255.255.255.0
vlan20:192.168.20.0 255.255.255.0
vlan30:192.168.30.0 255.255.255.0
1.switch2二层交换机：
switch(config)#vlan 10
switch(config-vlan)#vlan 20
switch(config)#int f0/2
switch(config-if)#switchport mode access
switch(config-if)#switchport access vlan 10
switch(config-if)#int f0/3
switch(config-if)#switchport mode access
switch(config-if)#switchport access vlan 20
switch(config-if)#int f0/1
switch(config-if)#switchport mode trunk
2.switch3二层交换机：
Switch>en
Switch#vlan database
Switch(vlan)#vlan 10 name vlan10
Switch(vlan)#vlan 20 name vlan20
Switch(vlan)#vlan 30 name vlan30
switch(config)#int f0/2
switch(config-if)#switchport mode access
switch(config-if)#switchport access vlan 10
switch(config-if)#int f0/3
switch(config-if)#switchport mode access
switch(config-if)#switchport access vlan 20
switch(config-if)#int f0/4
switch(config-if)#switchport access vlan 30
switch(config-if)#int f0/1
switch(config-if)#switchport mode trunk
3.switch3二层交换机：
Switch>en
Switch#vlan database
Switch(vlan)#vlan 10 name vlan10
Switch(vlan)#vlan 30 name vlan30
switch(config)#int f0/2
switch(config-if)#switchport mode access
switch(config-if)#switchport access vlan 10
switch(config-if)#int f0/3
switch(config-if)#switchport mode access
switch(config-if)#switchport access vlan 30
switch(config-if)#int f0/1
switch(config-if)#switchport mode trunk
4.switch0三层交换机
Switch>en
Switch#vlan database
Switch(vlan)#vlan 10 name vlan10
Switch(vlan)#vlan 20 name vlan20
Switch(vlan)#vlan 30 name vlan30
Switch(config)#int vlan 10
Switch(config-if)#ip address 192.168.10.1 255.255.255.0
Switch(config-if)#no shutdown
Switch(config-if)#exit
Switch(config)#int vlan 20
Switch(config-if)#ip address 192.168.20.1 255.255.255.0
Switch(config-if)#no shutdown
Switch(config-if)#exit
Switch(config)#int vlan 30
Switch(config-if)#ip address 192.168.30.1 255.255.255.0
Switch(config-if)#no shutdown
Switch(config-if)#exit
Switch(config)#ip routing //开启三层交换机的路由功能
Switch(config)#ip dhcp pool vlan10 //配置vlan10的ip地址池
Switch(dhcp-config)#network 192.168.10.0 255.255.255.0 //给vlan10配置网络号，和子网掩码
Switch(dhcp-config)#default-router 192.168.10.1 //配置默认网关
Switch(dhcp-config)#dns-server 114.144.114.114 //配置默认的DNS服务器地址，这里不配置也行。
Switch(dhcp-config)#exit
Switch(config)#ip dhcp pool vlan20
Switch(dhcp-config)#network 192.168.20.0 255.255.255.0
Switch(dhcp-config)#default-router 192.168.20.1
Switch(dhcp-config)#dns-server 114.114.114.114
Switch(dhcp-config)#exit
Switch(config)#ip dhcp pool vlan30
Switch(dhcp-config)#network 192.168.30.0 255.255.255.0
Switch(dhcp-config)#default-router 192.168.30.1
Switch(dhcp-config)#dns-server 114.114.114.114
Switch(dhcp-config)#exit
5.端口封装（三层交换机）：
interface f0/1
switchport trunk encapsulation dot1q
switchport mode trunk
interface f0/2
switchport trunk encapsulation dot1q
switchport mode trunk
interface f0/3
switchport trunk encapsulation dot1q
switchport mode trunk
补充思科交换机删除端口vlan：
int g0/1
no swtichport access vlan 100
no int vlan 100
no vlan 100
允许所有VLAN通过某端口：
interface f0/24
switchport mode trunk
switchport trunk allowed vlan all
将多端口同时划给同一VLAN,省得一个一个加：
Switch(config)#interface range f0/1-5
Switch(config-if-range)#switchport mode access
Switch(config-if-range)#switchport access vlan 10
Switch(config-if-range)#exit