Define DHCP Relay on Layer 3 on the SFE/SGE Stackable Managed Switches

Objective

The Dynamic Hosting Configuration Protocol (DHCP) is used to dynamically assign IP addresses to clients on the network. However, if a client is on a subnet that does not contain a DHCP server, the client cannot communicate with it to receive an IP address. If there is a DHCP relay in the subnet, the relay forwards the IP address request to a DHCP server, which then returns the IP address of the client to the DHCP relay, who then transmits it to the client. IP Addresses are controlled and distributed one by one to avoid overloading the device.The purpose of this document is to explain how to configure the SFE/SGE Stackable Managed Switches as DHCP relays on layer 3.

Applicable Devices

• SFE/SGE Stackable Managed Switches

Software Version

• v3.0.2.18

Configure Switch as a DHCP Relay

Step 1. Log in to the web configuration utility and choose System > System Management > IP Addressing > DHCP Relay > DHCP Server. The DHCP Server page opens:

Step 2. Choose Enable from the DHCP Relay drop-down list to enable the device as a DHCP relay.

Note: If you choose Enable, skip to Step 4.

Step 3. (Optional) Choose Enable from the Option 82 drop-down list to enable Option 82 on the device. Option 82 is used to provide information regarding the location of DHCP clients on the network.

Note: The Option 82 can only be enabled if DHCP snooping has been enabled. See Dynamic Host Configuration Protocol (DHCP) Snooping Properties on SFE/SGE Managed Switches to enable DHCP snooping.

Step 4. Click Apply, the changes are made and the device is configured.

Caution: This only saves your configuration to the running configuration file. This means any changes made will be lost if the device is rebooted. If you wish to save these changes even after a system reboot, you need to copy the running configuration file to the startup configuration file. See Copy Configuration File on SFE/SGE Series Managed Switches for more information on how to do this.

Add a DHCP Server

Step 1. Click the Add button to add a DHCP server. The Add DHCP Server window appears:

Note: The Supported IP Format field displays the version of Internet Protocol that is supported.

Step 2. Enter the IP address of the DHCP server in the DHCP Server IP Address field.

Step 3. Click Apply, the changes are made and the device is configured. The IP address is shown on the DHCP Server table.

Caution: This only saves your configuration to the running configuration file. This means any changes made will be lost if the device is rebooted. If you wish to save these changes even after a system reboot, you need to copy the running configuration file to the startup configuration file. See Copy Configuration File on SFE/SGE Series Managed Switches for more information on how to do this.

Delete a DHCP Server

Step 1. Check the DHCP server configuration from the DHCP Server check box that the administrator wants to delete.

Step 2. Click Delete, the changes are made and the device is configured.

Caution: This only saves your configuration to the running configuration file. This means any changes made will be lost if the device is rebooted. If you wish to save these changes even after a system reboot, you need to copy the running configuration file to the startup configuration file. See Copy Configuration File on SFE/SGE Series Managed Switches for more information on how to do this.