Products & Services

Training & Events

Partner Central

Hierarchical Navigation

HOME
- SUPPORT
  - PRODUCT SUPPORT
    - END-OF-SALE AND END-OF-LIFE PRODUCTS
      - CISCO IOS SOFTWARE RELEASES 12.2 T
        CONFIGURE
        FEATURE GUIDES
        DHCP Server - Option to Ignore All BOOTP Requests

Cisco IOS Software Releases 12.2 T

DHCP Server - Option to Ignore All BOOTP Requests

Downloads

DHCP Server - Option to Ignore All BOOTP Requests

Table Of Contents

DHCP Server—Option to Ignore All BOOTP Requests

Feature Overview

Benefits

Restrictions

Related Features and Technologies

Related Documents

Supported Platforms

Supported Standards, MIBs, and RFCs

Configuration Tasks

Configuring the Cisco IOS DHCP Server to Ignore All BOOTP Requests

Verifying DHCP Server—Option to Ignore All BOOTP Requests Feature Configuration

Configuration Examples

Option to Ignore all BOOTP Requests Example

Command Reference

ip dhcp bootp ignore

DHCP Server—Option to Ignore All BOOTP Requests

Feature History

Release

Modification

12.2(8)T

This feature was introduced.

This document describes the DHCP Server—Option to Ignore all BOOTP Requests feature and includes the following sections:

•Feature Overview

•Supported Platforms

•Supported Standards, MIBs, and RFCs

•Configuration Tasks

•Configuration Examples

•Command Reference

Feature Overview

The DHCP Server—Option to Ignore all BOOTP Requests feature introduces a new global configuration command: ip dhcp bootp ignore. This command allows the Cisco IOS Dynamic Host Configuration Protocol (DHCP) server to selectively ignore and not reply to received Bootstrap Protocol (BOOTP) request packets.

This feature is beneficial when there is a mix of BOOTP and DHCP clients in a network segment, and there is a BOOTP server and a Cisco IOS DHCP server servicing the network segment. The BOOTP server is configured with static bindings for the BOOTP clients and the BOOTP clients are intended to obtain their addresses from the BOOTP server. However, because a DHCP server can also respond to a BOOTP request, an address offer may be made by the DHCP server causing the BOOTP clients to boot with the address from the DHCP server, instead of the address from the BOOTP server. Configuring the DHCP server to ignore BOOTP requests means that the BOOTP clients will receive address information from the BOOTP server.

The Cisco IOS software can forward these ignored BOOTP request packets to another DHCP server if the ip helper-address interface configuration command is configured on the incoming interface.

Benefits

This feature is beneficial in network segments where BOOTP and DHCP clients coexist and both a BOOTP server and a Cisco IOS DHCP server service the network segment. The feature ensures that a BOOTP client will not inadvertently accept an address from a DHCP server.

Restrictions

The ip dhcp bootp ignore command applies to all DHCP pools configured on the router. This feature cannot selectively ignore BOOTP requests on a per-DHCP pool basis.

Related Features and Technologies

•BOOTP

•Cisco IOS DHCP server

Related Documents

•Cisco IOS IP Configuration Guide, Release 12.2

•Cisco IOS IP Command Reference, Volume 1 of 3: Addressing and Services, Release 12.2

Supported Platforms

•Cisco 805

•Cisco 820 series

•Cisco 1751

•Cisco 3620

•Cisco 3640

•Cisco 3660

•Cisco 7100 series

•Cisco 7200 series

•Cisco 7500 series

Determining Platform Support Through Cisco Feature Navigator

Cisco IOS software is packaged in feature sets that support specific platforms. To get updated information regarding platform support for this feature, access Cisco Feature Navigator. Cisco Feature Navigator dynamically updates the list of supported platforms as new platform support is added for the feature.

Cisco Feature Navigator is a web-based tool that enables you to quickly determine which Cisco IOS software images support a specific set of features and which features are supported in a specific Cisco IOS image. You can search by feature or release. Under the release section, you can compare releases side by side to display both the features unique to each software release and the features in common.

To access Cisco Feature Navigator, you must have an account on Cisco.com. If you have forgotten or lost your account information, send a blank e-mail to cco-locksmith@cisco.com. An automatic check will verify that your e-mail address is registered with Cisco.com. If the check is successful, account details with a new random password will be e-mailed to you. Qualified users can establish an account on Cisco.com by following the directions at http://www.cisco.com/register.

Cisco Feature Navigator is updated regularly when major Cisco IOS software releases and technology releases occur. For the most current information, go to the Cisco Feature Navigator home page at the following URL:

http://www.cisco.com/go/fn

Supported Standards, MIBs, and RFCs

Standards

No new or modified standards are supported by this feature.

MIBs

No new or modified MIBs are supported by this feature.

To obtain lists of supported MIBs by platform and Cisco IOS release, and to download MIB modules, go to the Cisco MIB website on Cisco.com at the following URL:

http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml

RFCs

No new or modified RFCs are supported by this feature.

Configuration Tasks

See the following section for configuration tasks for the DHCP Server—Option to Ignore all BOOTP Requests feature:

•Configuring the Cisco IOS DHCP Server to Ignore All BOOTP Requests (Required)

•Verifying DHCP Server—Option to Ignore All BOOTP Requests Feature Configuration (Optional)

Configuring the Cisco IOS DHCP Server to Ignore All BOOTP Requests

To allow the Cisco IOS DHCP server to selectively ignore and not reply to received BOOTP requests, use the following command in global configuration mode:

Command

Purpose

Router(config)# ip dhcp bootp ignore

Allows the Cisco IOS DHCP server to selectively ignore and not reply to received BOOTP requests.

Verifying DHCP Server—Option to Ignore All BOOTP Requests Feature Configuration

To verify that the DHCP Server—Option to Ignore all BOOTP Requests feature is configured correctly, use the following command in privileged EXEC mode:

Command

Purpose

Router(config)# more system:running-config

Displays the running configuration.

Configuration Examples

This section provides the following configuration example:

•Option to Ignore all BOOTP Requests Example

Option to Ignore all BOOTP Requests Example

The following example shows two DHCP pools that are configured on the router and that the router's DHCP server is configured to ignore all received BOOTP requests. If a BOOTP request is received from subnet 10.0.18.0/24, the request will be dropped by the router (because the ip helper-address command is not configured). If there is a BOOTP request from subnet 192.168.1.0/24, the request will be forwarded to 172.16.1.1 via the ip helper-address command.
!
version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router 
!
ip subnet-zero
!
ip dhcp bootp ignore
!
ip dhcp pool ABC
   network 192.168.1.0 255.255.255.0
   default-router 192.168.1.3 
   lease 2
!
ip dhcp pool DEF
   network 10.0.18.0 255.255.255.0
!
ip cef
!
interface FastEthernet0/0
 no ip address
 shutdown
 duplex half
!
interface Ethernet1/0
 ip address 10.0.18.68 255.255.255.0
 duplex half
!
interface Ethernet1/1
 ip address 192.168.1.1 255.255.255.0
 ip helper-address 172.16.1.1
 duplex half
!
interface Ethernet1/2
 shutdown
 duplex half
!
interface Ethernet1/3
 no ip address
 shutdown
 duplex half
!
interface FastEthernet2/0
 no ip address
 shutdown
 duplex half
!
ip route 172.16.1.1 255.255.255.255 e1/0 
no ip http server
no ip pim bidir-enable
!
call rsvp-sync
!
mgcp profile default
!
dial-peer cor custom
!
gatekeeper
 shutdown
!
line con 0
line aux 0
line vty 0 4
!
end
Command Reference

This section documents the new ip dhcp bootp ignore command. All other commands used with this feature are documented in the Cisco IOS Release 12.2 command reference publications.

ip dhcp bootp ignore

To allow the Cisco IOS DHCP server to selectively ignore and not reply to received Bootstrap Protocol (BOOTP) request packets, use the ip dhcp bootp ignore command in global configuration mode. To return to the default behavior, use the no form of this command.

ip dhcp bootp ignore
no ip dhcp bootp ignore
Syntax Description

This command has no arguments or keywords.

Defaults

Command Modes

Global configuration

Command History

Release

Modification

12.2(8)T

This command was introduced.

Usage Guidelines

The Cisco IOS software can forward these ignored BOOTP request packets to another DHCP server if the ip helper-address interface configuration command is configured on the incoming interface. If the ip helper-address command is not configured, the received BOOTP request will be dropped by the router.

Examples

The following example shows that the router will ignore received BOOTP requests:
hostname Router 
!
ip subnet-zero
!
ip dhcp bootp ignore
Related Commands

Command

Description

ip helper-address

Forwards UDP broadcasts, including BOOTP, received on an interface.