Cisco 802     IOS 12.0 (5)

 

 

ip dhcp-server

To specify which Dynamic Host Configuration Protocol (DHCP) servers to use on your network, specify the IP address of one or more DHCP servers available on the network, use the ip dhcp-server global configuration command. Use the no form of the command to remove a DHCP server's IP address.

ip dhcp-server [ip-address | name]
no ip dhcp-server [ip-address | name]

Syntax Description

ip-address

(Optional) IP address of a DHCP server.

name

(Optional) Name of a DHCP server.

 

 

Default

The IP limited broadcast address of 255.255.255.255 is used for transactions if no DHCP server is specified. This allows automatic detection of DHCP servers.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.0.

A DHCP server temporarily allocates network addresses to clients through the access server on an as-needed basis. While the client is active, the address is automatically renewed in a minimum of 20-minute increments. When the user terminates the session, the interface connection is terminated so that network resources can be quickly reused. You can specify up to ten servers on the network.

In normal situations, if a user's SLIP/PPP session fails (for example if a modem line disconnects), the allocated address will be reserved temporarily to preserve the same IP address for the client when dialed back into the server. This way, the session that was accidentally terminated can often be resumed.

To use the DHCP proxy-client feature, enable your access server to be a proxy-client on asynchronous interfaces by using the ip address-pool dhcp-proxy-client command. If you wish to specify which DHCP servers are used on your network, use the ip dhcp-server command to define up to ten specific DHCP servers.


Note To facilitate transmission, configure intermediary routers (or access servers with router functionality) to use an IP helper address whenever the DHCP server is not on the local LAN and the access server is using broadcasts to interact with the DHCP server. See "Configuring IP Addressing" in the Network Protocols Configuration Guide, Part 1.


The ip address-pool dhcp-proxy-client command initializes proxy-client status to all interfaces defined as asynchronous on the access server. To selectively disable proxy-client status on a single asynchronous interface, use the no peer default ip address interface command.

Example

The following command specifies a DHCP server with the IP address of 129.12.13.81:

ip dhcp-server 129.12.13.81

Related Commands

You can use the master indexes or search online to find documentation of related commands.

ip address-pool dhcp-proxy-client
ip helper address

peer default ip address pool
show dhcp

ip local pool

To configure a local pool of IP addresses to be used when a remote peer connects to a point-to-point interface, or to add a range of addresses to an existing pool, use the ip local pool global configuration command. To remove an address pool, or a range of addresses from a pool, use the appropriate no form of this command.

ip local pool {default | pool-name} low-ip-address [high-ip-address]
no ip local pool {default | pool-name}
no ip local pool {default | pool-name} low-ip-address [high-ip-address]


Note There are two ways to use the ip local pool command and its no forms; see the usage guidelines and examples for more explanation of use.


Syntax Description

default

Default local address pool that is used if no other pool is named.

pool-name

Name of a specific local address pool. (Always use the pool-name argument consistently.)

low-ip-address

Lowest IP address in the pool.

high-ip-address

(Optional) Highest IP address in the pool. If this value is omitted only the low-ip-address IP address is included in the local pool.

 

 

Default

No address pools are configured.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.0. Enhancements to the command were made in Releases 11.3AA and 12.0, to support multiple address ranges.

Use the ip local pool command to create one or more local address pools from which IP addresses are assigned when a peer connects. The default address pool is then used on all point-to-point interfaces after the ip address-pool local global configuration command is issued. To use a specific, named address pool on an interface, use the peer default ip address pool interface configuration command.

Use the shorter no form of the command to remove the entire address pool (default or specific).Use the longer no form of the command with appropriate keywords and arguments to remove a range of addresses from a pool.

These pools can also be used with the translate commands for one-step vty-async connections and in certain AAA/TACACS+ authorization functions. Refer to the "Configuring Protocol Translation and Virtual Asynchronous Devices" chapter in the Dial Solutions Configuration Guide and the "System Management" part of the Configuration Fundamentals Configuration Guide for more information. Pools can be displayed with the show ip local pool command.

Example

The following command creates a local IP address pool by the name of quark, which contains all local IP addresses from 172.16.23.0 to 172.16.23.255:

ip local pool quark 172.16.23.0 172.16.23.255
 

The following example configures a pool of 1024 IP addresses:

 2511(config)#no ip local pool default
 2511(config)#ip local pool default 1.1.1.0 1.1.4.255
 2511(config)#^Z
 2511#show ip local pool
  Pool     Begin           End             Free InUse
  default  1.1.1.0         1.1.4.255       1024  0
 

The following example configures multiple ranges of IP addresses into one pool:

 7206-9(config)#no ip local pool default
 7206-9(config)#ip local pool default 9.1.1.0 9.1.9.255
 7206-9(config)#ip local pool default 9.2.1.0 9.2.9.255
 7206-9(config)#^Z

 7206-9#show ip local pool
  Pool     Begin           End             Free    In use   Cache Size
  default  9.1.1.0         9.1.9.255       2304       0          20
           9.2.1.0         9.2.9.255       2304       0
 

Related Commands

You can use the master indexes or search online to find documentation of related commands.

ip address-pool
show ip local pool