Clearing the ARP cache table in ESXi 5.5

Products

• VMware vSphere ESXi

Issue/Introduction

This article provides information on the new esxcli command introduced in vSphere 5.5 to clear the ARP table. ESXi 3.x, 4.x, and ESXi 5.0/5.1 do not include any mechanism to clear the ARP table.

Note: The steps in this article do not apply to ESXi 6.0. Currently, the only supported method to clear the ARP cache in ESXi 6.0 is to reboot the host.

For more information, see Troubleshooting network connection issues using Address Resolution Protocol (ARP) (1008184).

Environment

VMware vSphere ESXi 5.5

Resolution

vSphere 5.5 introduces a new esxcli network ip neighbor remove command to clear the ARP cache table.

To clear the ARP cache table in ESXi 5.5, run this command:

esxcli network ip neighbor remove [options]

Where options include:

• -i string or --interface-name=string
  
  Where string is the name of the VMkernel network interface from which the neighbor entry must be removed. If this option is not specified, the neighbor is removed from all interfaces.
  
  
• -a address or --neighbor-addr=address
  
  Where address is the IPv4/IPv6 address of the neighbor. This is mandatory.
  
  
• -N instance or --netstack=instance
  
  Where instance is the network stack instance. If unspecified, the default netstack instance is used.
  
  
• -v number or --version=number
  
  Where number is the IP version and can either be 4 or 6. This is mandatory.

For example, to delete the ARP entry for address 10.131.0.103:

1. Connect to the ESXi 5.5 host using SSH. For more information, see Using Tech Support Mode in ESXi 4.1 and ESXi 5.x (1017910).
   
   
2. View the current ARP table using this command:
   
   # esxcli network ip neighbor list
   
   You see output similar to:
   
   Neighbor Mac Address Vmknic Expiry State Type
------------ ----------------- ------ ------- ----- -----
10.131.0.103 xx:xx:xx:xx:xx:xx vmk0 908 sec Unknown
10.131.0.179 xx:xx:xx:xx:xx:xy vmk0 1062 sec Unknown
   
   
3. To delete the ARP entry for address 10.131.0.103, run one of these commands:
   
   
   • # esxcli network ip neighbor remove -v 4 -a 10.131.0.103
   • # esxcli network ip neighbor remove --version=4 --neighbor-addr=10.131.0.103
     
     
4. View the ARP table again using this command:
   
   # esxcli network ip neighbor list
   
   You see output similar to:
   
   Neighbor Mac Address Vmknic Expiry State Type
------------ ----------------- ------ ------- ----- -----
10.131.0.179 xx:xx:xx:xx:xx:xz vmk0 750 sec Unknown

Additional Information

For more information, see Displaying the ARP and Neighbor Discovery cache for VMkernel network interfaces (2000130).

Troubleshooting network connectivity issues using Address Resolution Protocol (ARP)
Using Tech Support Mode in ESXi 4.1, ESXi 5.x, and ESXi 6.x
Displaying the ARP and Neighbor Discovery cache for VMkernel network interfaces
ESXi 5.5 での ARP キャッシュ テーブルのクリア
清除 ESXi 5.5 中的 ARP 缓存表