76 CHAPTER 4: NETWORK PROTOCOL OPERATION
[SW7750]vlan 2
[SW7750-vlan2]port Ethernet 1/0/2
[SW7750]interface vlan 2
[SW7750-VLAN-Interface2]ip address 1.1.2.1 255.255.0.0
6Configure the corresponding interface and gateway address of VLAN3.
[SW7750]vlan 3
[SW7750-vlan3]port Ethernet 1/0/3
[SW7750]interface vlan 3
[SW7750-VLAN-Interface3]ip address 21.2.2.1 255.255.0.0
7It is necessary to configure a VLAN for the servers. The corresponding interface
VLAN of the DHCP server group 1 is configured as 4000, and that of the group 2
is configured as 3001.
[SW7750]vlan 4000
[SW7750-vlan4000]port Ethernet 1/0/4
[SW7750]interface vlan 4000
[SW7750-VLAN-Interface4000]ip address 1.99.255.1 255.255.0.0
[SW7750]vlan 3001
[SW7750-vlan3001]port Ethernet 1/0/5
[SW7750]interface vlan 3001
[SW7750-VLAN-Interface3001]ip address 1.88.255.1 255.255.0.0
In this example, clients on VLAN2 will receive IP addresses from the servers in
DHCP server group 1 (VLAN 4000). Clients on VLAN3 will receive IP addresses
from the servers in DHCP server group 2 (VLAN 3001).
8Show the configuration of DHCP server groups in User view.
<SW7750>display dhcp-server 1
9Show the DHCP Server Group number corresponding to the VLAN interface in
User view.
<SW7750>display dhcp-server interface vlan-interface 2
<SW7750>display dhcp-server interface vlan-interface 3
Troubleshooting a DHCP
Relay Configuration
Perform the following procedure if a user cannot apply for an IP address
dynamically:
1Use the display dhcp-server groupNo command to check if the IP address of
the corresponding DHCP server has been configured.
2Use the display VLAN and display IP commands to check if the VLAN and the
corresponding interface IP address have been configured.
3Ping the configured DHCP Server to ensure that the link is connected.
4Ping the IP address of the VLAN interface of the switch to where the DHCP user is
connected from the DHCP server to make sure that the DHCP server can correctly
find the route of the network segment the user is on. If the ping execution fails,
check if the default gateway of the DHCP server has been configured as the
address of the VLAN interface that it locates on.
5If no problems are found in the last two steps, use the display dhcp-server
groupNo command to view the packet that has been received. If you only see the
Discover packet and there is no response packet, it means the DHCP Server has
not sent the message to the Switch 7750. In this case, check if the DHCP Server
has been configured properly. If the numbers of request and response packets are
normal, enable the debugging dhcp-relay in User view and then use the terminal