Learning IP Information From a DHCP Server

IP Address Renewals

When the DHCP server assigns an IP address to a remote client, it “leases” the address to the remote client for a finite or infinite amount of time. If the lease is about to expire and the remote client still has a dial-up connection, the access server renews the lease on behalf of the remote client. The access server attempts to renew the lease as long as the remote client maintains a dial-up connection.

Enabling and Disabling DHCP

The default DHCP setting on the access server is DHCP ENABLED. The following table lists the commands that you use to enable and disable DHCP:

To Do This:

Use This Command:

 

 

Enable DHCP.

DEFINE/SET/CHANGE INTERNET DHCP ENABLED

Disable DHCP.

DEFINE INTERNET DHCP DISABLED

 

 

Displaying the DHCP Setting

Use the SHOW/LIST/MONITOR INTERNET command to display the current DHCP setting. The example in the Displaying the Internet Address and Subnet Mask section in this chapter shows a typical display.

Configuring Default Values

If you enable DHCP but also want the access server to function in the event that a DCHP server is not available, you can define default values for some of the DHCP- learned IP information in NVRAM using DEFINE commands. Follow the procedures in this chapter for setting the IP address, subnet mask, DNS values, WINS values, and gateways. You can also use the Access Server Manager to set these values. See the Access Server Manager’s online help for details.

When the access server initializes, it writes the default values from NVRAM to RAM. If a DHCP server responds to the access server’s request for information, the DHCP- learned values overwrite the default values in RAM. If a DHCP server does not respond, the access server uses the default values.

Overriding DHCP-Learned Values

To override DHCP-learned values, use SET commands after initialization completes. Follow the procedures in this chapter for setting the IP address, DNS values, WINS values, and gateways or use the Access Server Manager (see the Access Server Manager online help for details).

7-30 TCP/IP Network Characteristics