写出中间多层交换机的代码（分Vlan、设置不同vlan网关、设置DHCP IP池等等）：

以下是一个示例代码，用于配置具有多层交换机的网络环境： // 设置 VLAN vlan 10 name Sales exit vlan 20 name Marketing exit // 配置 VLAN 网关 interface vlan 10 ip address 192.168.10.1 255.255.255.0 exit interface vlan 20 ip address 192.168.20.1 255.255.255.0 exit // 配置 DHCP IP 池 ip dhcp pool Sales network 192.168.10.0 255.255.255.0 default-router 192.168.10.1 dns-server 8.8.8.8 exit ip dhcp pool Marketing network 192.168.20.0 255.255.255.0 default-router 192.168.20.1 dns-server 8.8.8.8 exit // 配置端口 interface GigabitEthernet1/0/1 switchport mode access switchport access vlan 10 exit interface GigabitEthernet1/0/2 switchport mode access switchport access vlan 20 exit // 配置中间交换机 interface GigabitEthernet2/0/1 switchport mode trunk switchport trunk allowed vlan 10,20 exit interface GigabitEthernet2/0/2 switchport mode trunk switchport trunk allowed vlan 10,20 exit // 保存配置 write memory