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■ Store, manage, and provide client configuration parameters.
As a DHCP server, a Services Router can provide temporary IP addresses from an
IP address pool to all clients on a specified subnet, a process known as dynamic
binding. Services Routers can also perform static binding, assigning permanent IP
addresses to specific clients based on their media access control (MAC) addresses.
Static bindings take precedence over dynamic bindings.
DHCP Options
In addition to its primary DHCP functions, you can also configure the Services Router
to send configuration settings like the following to clients through DHCP:
■ IP address of the DHCP server (Services Router).
■ List of Domain Name System (DNS) and NetBIOS servers
■ List of gateway routers
■ IP address of the boot server and the filename of the boot file to use
■ DHCP options defined in RFC 2132, DHCP Options and BOOTP Vendor Extensions
Compatibility with Autoinstallation
Services Router DHCP server functions are compatible with the autoinstallation
feature. The DHCP server automatically checks any autoinstallation settings for
conflicts and gives the autoinstallation settings priority over corresponding DHCP
settings. For example, an IP address set by autoinstallation takes precedence over
an IP address set by the DHCP server.
(To configure autoinstallation, see “Configuring Autoinstallation” on page 81.)
Conflict Detection and Resolution
A client that receives an IP address from the Services Router operating as a DHCP
server performs a series of Address Resolution Protocol (ARP) tests to verify that the
address is available and no conflicts exist. If the client detects an address conflict, it
informs the DHCP server about the conflict and can request another IP address from
the DHCP server.
The Services Router maintains a log of all client-detected conflicts and removes
addresses with conflicts from the DHCP address pool. To display the conflicts list,
you use the show system services dhcp conflict command. The addresses in the
conflicts list remain excluded until you use the clear system services dhcp conflict
command to manually clear the list.
Interface Restrictions
The Services Router supports DHCP client requests received on Fast Ethernet
interfaces only. However, DHCP requests received from a relay agent are supported
on all interface types.
DHCP Overview ■ 65
Chapter 4: Configuring the Router as a DHCP Server