Alcatel-Lucent 6850-48 Guida Di Rete
Configuring DHCP Relay
DHCP Relay Implementation
OmniSwitch AOS Release 6 Network Configuration Guide
September 2009
page 31-9
DHCP Relay Implementation
The OmniSwitch allows you to configure the DHCP Relay feature in one of two ways. You can set up a
global DHCP request or you can set up the DHCP Relay based on the VLAN of the DHCP request. Both
of these choices provide the same configuration options and capabilities. However, they are mutually
exclusive. The following matrix summarizes the options.
global DHCP request or you can set up the DHCP Relay based on the VLAN of the DHCP request. Both
of these choices provide the same configuration options and capabilities. However, they are mutually
exclusive. The following matrix summarizes the options.
Global DHCP
For the global DHCP service, you must identify an IP address for the DHCP server.
Setting the IP Address
The DHCP Relay is automatically enabled on a switch whenever a DHCP server IP address is defined by
using the
using the
service. You should configure DHCP Relay on switches where packets are routed between IP networks.
The following command defines a DHCP server address:
The following command defines a DHCP server address:
-> ip helper address 125.255.17.11
The DHCP Relay forwards BOOTP/DHCP broadcasts to and from the specified address. If multiple
DHCP servers are used, one IP address must be configured for each server. You can configure up to 256
addresses for each relay service.
DHCP servers are used, one IP address must be configured for each server. You can configure up to 256
addresses for each relay service.
To delete an IP address, use the no form of the
with this syntax will be deleted. If an IP address is not specified with this syntax, then all IP helper
addresses are deleted. The following command deletes an IP helper address:
addresses are deleted. The following command deletes an IP helper address:
-> ip helper no address 125.255.17.11
Per-VLAN DHCP
For the Per-VLAN DHCP service, you must identify the number of the VLAN that makes the relay
request.
request.
Identifying the VLAN
You may enter one or more server IP addresses to which packets will be sent from a specified VLAN. Do
this by using the
this by using the
command. The following syntax will identify the IP address
125.255.17.11 as the DHCP server for VLAN 3:
-> ip helper address 125.255.17.11 vlan 3
The following syntax identifies two DHCP servers for VLAN 4 at two different IP addresses:
-> ip helper address 125.255.17.11 125.255.18.11 vlan 4
Per-VLAN DHCP Relay
Global DHCP Relay
Effect
Disabled
Disabled
DHCP Request is flooded within its VLAN
Disabled
Enabled
DHCP Request is relayed to the Global Relay
Enabled
Disabled
DHCP Request is relayed to the Per-VLAN Relay
Enabled
Enabled
N/A