Learning IP Information From a DHCP Server

Learning IP Information From a DHCP Server

Description

You can use the Dynamic Host Configuration Protocol (DHCP) to automatically configure TCP/IP characteristics on the access server and remote clients. DHCP provides dynamic assignment of IP addresses and discovery of IP configuration parameters (for example, subnet mask or default gateways). A DHCP client requests and receives this information from a DHCP server on the network.

Enabling DHCP on the access server allows it to learn some of its IP configuration information from a DHCP server. The access server does not receive its IP address from the DHCP server; you must manually configure it or use a BOOTP server.

Enabling DHCP on the access server also allows remote dial-up clients to receive dynamically assigned IP addresses and IP configuration parameters from the DHCP server. Depending on the situation, the access server acts as a DHCP client or proxy.

By default, the DHCP setting on the access server is ENABLED. If you do not have a DHCP server on your network, disable DHCP. (See the Enabling and Disabling DHCP section in this chapter.)

BOOTP and DHCP Differences

DHCP is an extension of BOOTP; however, using a DHCP server to obtain IP information differs from using a BOOTP server in the following ways:

Using a BOOTP Server

Using a DHCP Server

The access server can learn its IP address from a BOOTP server (or you can configure it directly on the access server).

The access server does not learn its IP address from a DHCP server. The access server can learn the following from a DHCP server:

Domain name

Default gateway

Domain Name System (DNS) servers

Windows Internet Naming Service (WINS) servers

You configure the IP information to be learned in the BOOTP server’s database and associate it with the access server’s hardware address.

You do not configure the DHCP server with any access server or client-specific information. You need only to configure the DECserver with network information (for example, a domain name) and a pool of IP addresses available for assignment.

TCP/IP Network Characteristics 7-27