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CISCO-IP-IF-MIB Support for IP Helper Addresses

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Table Of Contents

CISCO-IP-IF-MIB Support for IP Helper Addresses

Finding Feature Information

Contents

Prerequisites for the CISCO-IP-IF-MIB (IP Helper MIB)

Information About the CISCO-IP-IF-MIB (IP Helper MIB)

Overview of the CISCO-IP-IF-MIB (IP Helper MIB)

How to Configure SNMP and Retrieve the CISCO-IP-IF-MIB (IP Helper MIB)

Configuring the Router to Use SNMP

What to Do Next

Configuration Examples for CISCO-IP-IF-MIB

Additional References

Related Documents

Standards

MIBs

Technical Assistance

Feature Information for the CISCO-IP-IF-MIB

Glossary


CISCO-IP-IF-MIB Support for IP Helper Addresses

First Published: March 31, 2009
Last Updated: March 31, 2009

This module contains information about IP helper MIBs used with interfaces and hardware components. Network architectures are commonly deployed where Cisco routers are used as DHCP relays. Multiple servers are often specified in Cisco IOS router DHCP relay configuration through IP helper addresses. These IP helper addresses are critical because they enable the router to forward DHCP broadcasts, thus eliminating the need for a DHCP server on each network segment. This feature utilizes the CISCO-IP-IF-MIB to enable customers to retrieve all IP helper addresses that are configured on each interface.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for the CISCO-IP-IF-MIB" section.

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

•Prerequisites for the CISCO-IP-IF-MIB (IP Helper MIB)

•Information About the CISCO-IP-IF-MIB (IP Helper MIB)

•How to Configure SNMP and Retrieve the CISCO-IP-IF-MIB (IP Helper MIB)

•Configuration Examples for CISCO-IP-IF-MIB

•Standards

•Feature Information for the CISCO-IP-IF-MIB

•Glossary

Prerequisites for the CISCO-IP-IF-MIB (IP Helper MIB)

Configure Simple Network Management Protocol (SNMP) on the router on which the IP helper MIB feature is to be used. See the "Configuring the Router to Use SNMP" section for more information. For more information on configuring an SNMP server, see the "Configuring SNMP Support" chapter of the Cisco IOS Network Management Configuration Guide.

Information About the CISCO-IP-IF-MIB (IP Helper MIB)

To configure the SNMP and to retrieve all IP helper addresses configured on each interface, you should understand the following concept:

•Overview of the CISCO-IP-IF-MIB (IP Helper MIB)

Overview of the CISCO-IP-IF-MIB (IP Helper MIB)

Network architectures are commonly deployed where Cisco routers are used as DHCP relays. Multiple servers are often specified in Cisco IOS router DHCP relay configuration through IP helper addresses. The IP helper addresses enable routers to forward various types of broadcast traffic. These addresses eliminate the need to deploy DHCP servers on each network segment, thus reducing costs and simplifying DHCP management.

This feature delivers new functionality that enables all IP Helper addresses configured on each interface to be stored (and retrieved via SNMP) in the MIB.

The ciiHelperAddressTable in the CISCO-IP-IF-MIB (the IP helper MIB) enables you to retrieve all IP helper addresses that are configured on each interface to be stored (and retrieved through the SNMP) in the MIB.

The ciiHelperAddressTable in the CISCO-IP-IF-MIB accesses the multiple set of addresses through a network (SNMP) management station. The CISCO-IP-IF-MIB accesses all the configured IP helper addresses on an interface.

How to Configure SNMP and Retrieve the CISCO-IP-IF-MIB (IP Helper MIB)

This section contains the following procedure:

•Configuring the Router to Use SNMP (required)

Configuring the Router to Use SNMP

Note The task described in this section include examples of the SNMP CLI syntax used to set configuration parameters on the router and to read values from MIB objects on the router. These SNMP CLI syntax examples are taken from a Linux workstation using public domain SNMP tools. The SNMP CLI syntax for your workstation might be different. See the documentation that was provided with your SNMP tools for the correct syntax for your network management workstation.

Before you can use the CISCO-IP-IF-MIB feature, you must first configure the router to support SNMP. Perform this task to enable SNMP on the router.

SUMMARY STEPS

1. enable

2. configure terminal

3. snmp-server community string1 ro

4. snmp-server community string2 rw

5. end

DETAILED STEPS

 
Command or Action
Purpose

Step 1 

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2 

configure terminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3 

snmp-server community string1 ro

Example:

Router(config)# snmp-server community public ro

Sets up the community access string to permit access to SNMP.

•The string1 argument is a community string that consists of 1 to 32 alphanumeric characters and functions much like a password, permitting access to the SNMP protocol. Blank spaces are not permitted in the community string.

•The ro keyword specifies read-only access. SNMP management stations that use this string can retrieve MIB objects.

Note The SNMP community read-only (RO) string for the example is public. You should use a more complex string for this value in your configuration.

Step 4 

snmp-server community string2 rw

Example:

Router(config)# snmp-server community private rw

Sets up the community access string to permit access to SNMP.

•The string2 argument is a community string that consists of 1 to 32 alphanumeric characters and functions much like a password, permitting access to the SNMP protocol. Blank spaces are not permitted in the community string.

•The rw keyword specifies read-write access. SNMP management stations that use this string can retrieve and modify MIB objects.

Note The SNMP community read-write (RW) string for the example is private. You should use a more complex string for this value in your configuration.

Step 5 

end

Example:

Router(config)# end

Exits the current configuration mode and returns to privileged EXEC mode.

What to Do Next

Retrieving IP Helper Addresses

After configuring the router to support SNMP, the ciiHelperAddressTable in the CISCO-IP-IF-MIB (the IP helper MIB) is used to retrieve all IP helper addresses configured on each interface and to store the addresses in a configuration file. The IP helper addresses are retrieved each time the router acts as a DHCP relay.

Configuration Examples for CISCO-IP-IF-MIB

The following example shows the list of retrieved IP helper addresses in a configuration file: 

!

interface FastEthernet1/0.1

 encapsulation dot1Q 501

!

interface FastEthernet1/0.2

 encapsulation dot1Q 502

 ip helper-address 209.165.202.129

!

interface FastEthernet1/0.3

 encapsulation dot1Q 503

 ip helper-address 209.165.202.129

!

interface FastEthernet2/0

 ip helper-address 209.165.200.225

 ip helper-address 209.165.200.227

 ip helper-address 209.165.200.254

 ip helper-address 209.165.200.226

 ip helper-address 209.165.202.129

 shutdown

 duplex half

!

interface ATM6/0

 no ip address

 ip helper-address 209.165.201.10

 ip helper-address 209.165.201.5

 shutdown

 no atm enable-ilmi-trap

!

The preceding Cisco IOS configuration provides the following output: 

~> snmpbulkget -v2c -Ob -c public <ip-address> 1.3.6.1.4.1.9.9.309.1.2.1

CISCO-IP-IF-MIB::ciiHelperAddressStatus.4.0.1.4.209.165.200.225 = INTEGER: notInService(2)

CISCO-IP-IF-MIB::ciiHelperAddressStatus.4.0.1.4.209.165.200.226 = INTEGER: notInService(2)

CISCO-IP-IF-MIB::ciiHelperAddressStatus.4.0.1.4.209.165.200.227 = INTEGER: notInService(2)

CISCO-IP-IF-MIB::ciiHelperAddressStatus.4.0.1.4.209.165.200.254 = INTEGER: notInService(2)

CISCO-IP-IF-MIB::ciiHelperAddressStatus.4.0.1.4.209.165.202.129 = INTEGER: notInService(2)

CISCO-IP-IF-MIB::ciiHelperAddressStatus.9.0.1.4.209.165.202.129 = INTEGER: active(1)

CISCO-IP-IF-MIB::ciiHelperAddressStatus.10.0.1.4.209.165.202.129 = INTEGER: active(1)

CISCO-IP-IF-MIB::ciiHelperAddressStatus.15.0.1.4.209.165.201.5 = INTEGER: notInService(2)

CISCO-IP-IF-MIB::ciiHelperAddressStatus.15.0.1.4.209.165.201.10 = INTEGER: notInService(2)

CISCO-IP-IF-MIB::ciiHelperAddressStorage.4.0.1.4.209.165.200.225 = INTEGER: nonVolatile(3)

CISCO-IP-IF-MIB::ciiHelperAddressStorage.4.0.1.4.209.165.200.226 = INTEGER: nonVolatile(3)

CISCO-IP-IF-MIB::ciiHelperAddressStorage.4.0.1.4.209.165.200.227 = INTEGER: nonVolatile(3)

CISCO-IP-IF-MIB::ciiHelperAddressStorage.4.0.1.4.209.165.200.254 = INTEGER: nonVolatile(3)

CISCO-IP-IF-MIB::ciiHelperAddressStorage.4.0.1.4.209.165.202.129 = INTEGER: nonVolatile(3)

CISCO-IP-IF-MIB::ciiHelperAddressStorage.9.0.1.4.209.165.202.129 = INTEGER: nonVolatile(3)

CISCO-IP-IF-MIB::ciiHelperAddressStorage.10.0.1.4.209.165.202.129 = INTEGER: 
nonVolatile(3)

CISCO-IP-IF-MIB::ciiHelperAddressStorage.15.0.1.4.209.165.201.5 = INTEGER: nonVolatile(3)

CISCO-IP-IF-MIB::ciiHelperAddressStorage.15.0.1.4.209.165.201.10 = INTEGER: nonVolatile(3)

Additional References

The following sections provide references related to the CISCO-IP-IF-MIB.

Related Documents

Related Topic
Document Title

SNMP commands, complete command syntax, command reference, command history, defaults, defaults, usage guidelines, and examples

Cisco IOS Network Management Command Reference

SNMP Configuration

"Configuring SNMP Support" chapter of the Cisco IOS Network Management Configuration Guide


Standards

Standard
Title

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

—


MIBs

MIB
MIBs Link

CISCO-IP-IF-MIB

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

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


Technical Assistance

Description
Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/techsupport


Feature Information for the CISCO-IP-IF-MIB

Table 1 lists the release history for this feature.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Note Table 1 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.

Table 1 Feature Information for the CISCO-IP-IF-MIB

Feature Name
Releases
Feature Information

CISCO-IP-IF-MIB Support for IP Helper Addresses

12.2(33)SXI1

The CISCO-IP-IF-MIB support for IP Helper Addresses feature enables you to retrieve all IP helper addresses that are configured on each interface.


Glossary

DHCP—Dynamic Host Configuration Protocol. Provides a mechanism for allocating IP addresses dynamically so that addresses can be reused when hosts no longer need them.

MIB—Management Information Base. Database of network management information that is used and maintained by a network management protocol, such as SNMP or CMIP. The value of a MIB object can be changed or retrieved using SNMP or CMIP commands, usually through a GUI network management system. MIB objects are organized in a tree structure that includes public (standard) and private (proprietary) branches.

SNMP—Simple Network Management Protocol. A network management protocol used almost exclusively in TCP/IP networks. SNMP provides a means to monitor and control network devices and to manage configurations, statistics collection, performance, and security.

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All other trademarks mentioned in this document or website are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (0903R)

Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.

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