Manual

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229
no ip forward-protocol udp bootps
packet forwarding.
Interface Configuration Mode
ip helper-address <ipaddress>
no ip helper-address <ipaddress>
Set the destination IP address for DHCP relay
forwarding; the “no ip helper-address
<ipaddress>“command cancels the setting.
3. Configure share-vlan
When the user want to use layer 2 device as DHCP relay, there is the number limitation that
create layer 3 interface on layer 2 device, but using the layer 3 interface of share-vlan (it may
include many sub-vlan, however a sub-vlan only correspond to a share-vlan) can implement
DHCP relay forwarding, and the relay device needs to enable option82 function at the same
time.
Command
Explanation
Global Mode
ip dhcp relay share-vlan <vlanid>
sub-vlan <vlanlist>
no dhcp relay share-vlan
Create or delete share-vlan and it's sub-vlan.
29.4 DHCP Configuration Examples
Scenario 1:
Too save configuration efforts of network administrators and users, a company is using switch
as a DHCP server. The Admin VLAN IP address is 10.16.1.2/16. The local area network for the
company is divided into network A and B according to the office locations. The network
configurations for location A and B are shown below.
PoolA(network 10.16.1.0)
PoolB(network 10.16.2.0)
Device
IP address
Device
IP address
Default gateway
10.16.1.200
10.16.1.201
Default gateway
10.16.1.200
10.16.1.201
DNS server
10.16.1.202
DNS server
10.16.1.202
WINS server
10.16.1.209
WWW server
10.16.1.209
WINS node type
H-node
Lease
3 days
Lease
1day
In location A, a machine with MAC address 00-03-22-23-dc-ab is assigned with a fixed IP
address of 10.16.1.210 and named as “management”.