IPv6 Configuration Guide, Cisco IOS XE Release 3S
IPv6 Neighbor Discovery Cache
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Contents

IPv6 Neighbor Discovery Cache

Last Updated: July 31, 2012

The IPv6 neighbor discovery cache feature allows static entries to be made in the IPv6 neighbor cache.

The per-interface neighbor discovery cache limit function can be used to prevent any particular customer attached to an interface from overloading the neighbor discovery cache, whether intentionally or unintentionally.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 table at the end of this module.

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

Information About IPv6 Static Cache Entry for Neighbor Discovery

IPv6 Neighbor Discovery

The IPv6 neighbor discovery process uses ICMP messages and solicited-node multicast addresses to determine the link-layer address of a neighbor on the same network (local link), verify the reachability of a neighbor, and track neighboring devices.

The IPv6 static cache entry for neighbor discovery feature allows static entries to be made in the IPv6 neighbor cache. Static routing requires an administrator to manually enter IPv6 addresses, subnet masks, gateways, and corresponding Media Access Control (MAC) addresses for each interface of each device into a table. Static routing enables more control but requires more work to maintain the table. The table must be updated each time routes are added or changed.

Per-Interface Neighbor Discovery Cache Limit

The number of entries in the Neighbor Discovery cache can be limited by interface. Once the limit is reached, no new entries are allowed. The per-interface Neighbor Discovery cache limit function can be used to prevent any particular customer attached to an interface from overloading the Neighbor Discovery cache, whether intentionally or unintentionally.

When this feature is enabled globally, a common per-interface cache size limit is configured on all interfaces on the device. When this feature is enabled per interface, a cache size limit is configured on the associated interface. The per-interface limit overrides any globally configured limit.

How to Configure IPv6 Neighbor Discovery Cache

Configuring a Neighbor Discovery Cache Limit on a Specified Interface

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    interface type number

4.    ipv6 nd cache interface-limit size [log rate]


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
interface type number


Example:

Device(config)# interface GigabitEthernet 1/0/0

 

Specifies an interface type and number, and places the device in interface configuration mode.

 
Step 4
ipv6 nd cache interface-limit size [log rate]


Example:

Device(config-if)# ipv6 nd cache interface-limit 1

 

Configures a Neighbor Discovery cache limit on a specified interface on the device.

  • Issuing this command overrides any configuration that may have been created by issuing the ipv6 nd cache interface-limit in global configuration mode.
 

Configuring a Neighbor Discovery Cache Limit on All Device Interfaces

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    ipv6 nd cache interface-limit size [log rate]


DETAILED STEPS
 Command or ActionPurpose
Step 1
enable


Example:

Device> enable

 

Enables privileged EXEC mode.

  • Enter your password if prompted.
 
Step 2
configure terminal


Example:

Device# configure terminal

 

Enters global configuration mode.

 
Step 3
ipv6 nd cache interface-limit size [log rate]


Example:

Device(config)# ipv6 nd cache interface-limit 4

 

Configures a neighbor discovery cache limit on all interfaces on the device.

 

Configuration Examples for IPv6 Neighbor Discovery Cache

Example: Configuring a Neighbor Discovery Cache Limit

Device# show ipv6 interface GigabitEthernet2/0/0

Interface GigabitEthernet2/0/0, entries 2, static 0, limit 4 

IPv6 Address               Age Link-layer Addr State  Interface
2001:0db8::94               	 0 aabb.cc00.5d02    REACH  GE2/0/0
FE80::A8BB:CCFF:FE00:5D02  0 aabb.cc00.5d02    DELAY  GE2/0/0

Additional References

Related Documents

Related Topic Document Title

IPv6 addressing and connectivity

IPv6 Configuration Guide

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

IPv6 commands

Cisco IOS IPv6 Command Reference

Cisco IOS IPv6 features

Cisco IOS IPv6 Feature Mapping

Standards and RFCs

Standard/RFC Title

RFCs for IPv6

IPv6 RFCs

MIBs

MIB

MIBs Link

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

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 and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html

Feature Information for IPv6 Neighbor Discovery Cache

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

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

Table 1Feature Information for IPv6 Neighbor Discovery Cache
Feature Name Releases Feature Information

IPv6: Per-Interface Neighbor Discovery Cache Limit

15.1(3)T

Cisco IOS XE Release 2.6

The per-interface neighbor discovery cache limit function can be used to prevent any particular customer attached to an interface from overloading the neighbor discovery cache, whether intentionally or unintentionally.

The following commands were introduced or modified: ipv6 nd cache interface-limit, show ipv6 interface.

IPv6 Static Cache Entry for Neighbor Discovery

12.2(8)T

12.2(17)SX1

12.2(25)SEA

12.2(25)SG

12.2(33)SRA

Cisco IOS XE Release 2.1

15.0(2)SG

3.2.0SG

The IPv6 static cache entry for Neighbor Discovery feature allows static entries to be made in the IPv6 neighbor cache.

The following commands were introduced or modified: ipv6 nd cache interface-limit, show ipv6 interface.

Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned 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. (1110R)

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.

© 2012 Cisco Systems, Inc. All rights reserved.