SW2(config)#int rang fa0/23-24

SW2(config-if-range)#ip dhcp snooping trust

测试：

Client3(config)#interface fa0/1 Client3(config-if)#no shutdown Client3(config-if)#ip address dhcp

*Jan 31 03:25:54.103: %DHCP-6-ADDRESS_ASSIGN: Interface FastEthernet0/1 assigned DHCP address 192.168.20.3, mask 255.255.255.0, hostname Client3 Client2(config-if)#

sw1#show ip dhcp snooping binding

MacAddress IpAddress Lease(sec) Type VLAN Interface

------------------ --------------- ---------- ------------- ---- --------------------

58:35:D9:B1:36:69 192.168.20.3 85861 dhcp-snooping 2 FastEthernet0/24

Total number of bindings: 1 sw1#

Note:

当连接服务器的交换机不插入82 option，另一台插入option后，不能拿地址；所以比较好的办法为在服务器上定义relay trust option，交换机全部插入option。