PLANET XGS3-24040 - Manual (Page 233)

Chapter 31 DHCP Snooping Configuration
30-5
since the Switch3 appends the port information of accessing Switch3 to the request message from the client,
the server can tell that whether the client is from the network of Swich1 or Swich2, and thus can allocate
separate address spaces for the two networks, to simplify the management of networks.
The following is the configuration of Switch3(MAC address is 00:03:0f:02:33:01):
Switch3(config)#service dhcp
Switch3(config)#ip dhcp relay information option
Switch3(config)#ip forward-protocol udp bootps
Switch3(Config-if-vlan3)#ip address 192.168.10.222 255.255.255.0
Switch3(Config-if-vlan2)#ip address 192.168.102.2 255.255.255.0
Switch3(Config-if-vlan2)#ip helper 192.168.10.88
Linux ISC DHCP Server supports option 82, its configuration file /etc/dhcpd.con is ddns-update-style interim;
ignore client-updates;
class "Switch3Vlan2Class1" {
match if option agent.circuit-id = "Vlan2+Ethernet1/2" and option agent.remote-id=00:03:0f:02:33:01;
}
class "Switch3Vlan2Class2" {
match if option agent.circuit-id = "Vlan2+Ethernet1/3" and option agent.remote-id=00:03:0f:02:33:01;
}
subnet 192.168.102.0 netmask 255.255.255.0 {
option routers 192.168.102.2;
option subnet-mask 255.255.255.0;
option domain-name "example.com.cn";
option domain-name-servers 192.168.10.3;
authoritative;
pool {
range 192.168.102.21 192.168.102.50;
default-lease-time 86400; #24 Hours
max-lease-time 172800; #48 Hours
allow members of "Switch3Vlan2Class1";
}
pool {
range 192.168.102.51 192.168.102.80;
default-lease-time 43200; #12 Hours
max-lease-time 86400; #24 Hours
allow members of "Switch3Vlan2Class2";
}
}
Now, the DHCP server will allocate addresses for the network nodes from Switch1 which are relayed by
Switch3 within the range of 192.168.102.21 ~ 192.168.102.50, and allocate addresses for the network nodes
from Switch1 within the range of 192.168.102.51～192.168.102.80.