The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.
Contents
The IPv6 highly scalable neighbor discovery feature optimizes IPv6 neighbor discovery by providing Neighbor Discovery (ND) cache autorefresh, unsolicited NA gleaning, and neighbor unreachability detection (NUD) exponential retransmit. This feature makes ND more robust in a large-scale deployment
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.
Neighbor discovery (ND) protocol enforces neighbor unreachability detection (NUD), which can detect failing nodes or routers and changes, to link-layer addresses. NUD is used to maintain reachability information for all paths between hosts and neighboring nodes, including host-to-host, host-to-router, and router-to-host communication.
The neighbor cache maintains mapping information about the IPv6 link-local or global address to the link-layer address. The neighbor cache also maintains the neighbor's reachability state, which is updated using NUD. Neighbors can be in one of the following five possible states:
Use the ipv6 nd na glean command to configure ND to glean an entry from an unsolicited neighbor advertisement (NA).
Use the ipv6 nd nud retry command to configure ND to maintain an ND cache entry for a neighbor during network disruption.
Use the ipv6 nd cache expire refresh command to configure the neighbor to maintain an ND cache entry, when no traffic is sent to the neighbor.
1.
enable
2.
configure
terminal
3.
interface
type
number
4.
ipv6
nd
nud
retry base
interval
max-attempts
[final-wait-time]
5.
ipv6
nd
cache
expire
expire-time-in-seconds [refresh]
6.
ipv6 nd na glean
7. end
In the following example, IPv6 ND NA gleaning is enabled and the IPv6 ND cache expiry is set to 7200 seconds (2 hours):
interface Port-channel189 no ip address ipv6 address FC07::789:1:0:0:3/64 ipv6 nd nud retry 1 1000 3 1000 ipv6 nd na glean ipv6 nd cache expire 7200 no ipv6 redirects
Related Topic |
Document Title |
---|---|
IPv6 addressing and connectivity |
IPv6 Configuration Guide |
Cisco IOS commands |
|
IPv6 commands |
Cisco IOS IPv6 Command Reference |
Cisco IOS IPv6 features |
Standard/RFC |
Title |
---|---|
RFCs for IPv6 |
IPv6 RFCs |
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: |
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. |
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.
Feature Name |
Releases |
Feature Information |
---|---|---|
Enhanced IPv6 Neighbor Discovery Cache Management |
12.2(33)SXI7 Cisco IOS Release 15.2(1)E |
The IPv6 highly scalable neighbor discovery feature optimizes IPv6 neighbor discovery by providing ND cache autorefresh, unsolicited NA gleaning, and NUD exponential retransmit. The following commands were introduced or modified: ipv6 nd cache expire, ipv6 nd na glean, ipv6 nd nud retry. |