ARP Optimization
The ARP Optimization feature improves Address Resolution Protocol (ARP) performance by reducing the ARP searching time by using an improved data structure. Previously, the ARP table was organized for easy searching on an entry based on the IP address. However, there are cases, such as interface flapping on the device and a topology change in the network, where all related ARP entries must be refreshed for correct forwarding. This situation could consume a substantial amount of CPU time in the ARP process to search and clean up all the entries. Use the clear arp interface command to clear the entire ARP cache on an interface.
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 ARP Optimization
Benefits of ARP Optimization
The ARP Optimization feature improves Address Resolution Protocol (ARP) performance by reducing the ARP searching time by using an improved data structure. Previously, the ARP table was organized for easy searching on an entry based on the IP address. However, there are cases, such as interface flapping on the device and a topology change in the network, where all related ARP entries must be refreshed for correct forwarding. This situation could consume a substantial amount of CPU time in the ARP process to search and clean up all the entries. Use the clear arp interface command to clear the entire ARP cache on an interface.
How to Configure ARP Optimization
Clearing the ARP Cache
Perform the following tasks to clear the Address Resolution Protocol (ARP) cache of entries associated with an interface and to clear all dynamic entries from the ARP cache, the fast-switching cache, and the IP route cache.
DETAILED STEPS
Configuration Examples for ARP Optimization
Examples: Clearing the ARP Cache
The following example shows how to clear all entries in the ARP cache associated with an interface:
Device# clear arp interface gigabitethernet0/0/0
The following example shows how to clear all dynamic entries in the ARP cache:
Device# clear arp-cache
Additional References
Related Documents
| Related Topic | Document Title |
|---|---|
| Cisco IOS commands |
|
| ARP commands |
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. |
Feature Information for ARP Optimization
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 1 | Feature Information for ARP Optimization |
| Feature Name | Releases | Feature Information |
|---|---|---|
| ARP Optimization |
12.2(15)T 15.0(1)S Cisco IOS XE Release 2.1 Cisco IOS XE Release 3.2SE |
The ARP Optimization feature improves Address Resolution Protocol (ARP) performance by reducing the ARP searching time by using an improved data structure. Previously, the ARP table was organized for easy searching on an entry based on the IP address. However, there are cases, such as interface flapping on the device and a topology change in the network, where all related ARP entries must be refreshed for correct forwarding. This situation could consume a substantial amount of CPU time in the ARP process to search and clean up all the entries. Use the clear arp interface command to clear the entire ARP cache on an interface. The following command was introduced or modified: clear arp interface. |
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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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