Beacon packets are sent even if the vSwitch is not configured to use Beacon Probing for Network Failover Detection

Products

• VMware vSphere ESXi

Issue/Introduction

This article provides steps to disable transmission of Beacon Packets when Beacon Probing is not used for Network Failover Detection.

Symptoms:

• ESXi/ESX sends Beacon Packets when the vNetwork Distributed Switch (vDS) or vSwitch is connected to more than one uplink.
• ESXi/ESX sends a periodic broadcast of Beacon Packets even if the vDS or vSwitch is not configured to use Beacon Probing for Network Failover Detection.
• This issue occurs when these packets have the virtual MAC of the vmnic in the Source MAC Address field.
• LLC Broadcasts with the source MAC as the Virtual MAC of a vmnic is seen in a capture from the upstream switch.

Environment

VMware ESXi 4.0.x Embedded
VMware ESX 4.0.x
VMware ESXi 4.0.x Installable

Resolution

To resolve this issue, disable transmission of Beacon Packets with vSphere Client or in the ESXi/ESX console.

To disable transmission of Beacon Packets in vSphere Client:

1. Log in to vCenter Server or to the ESXi/ESX host using vSphere Client.
2. Select the ESXi/ESX host on which you need to disable Beacon Probing.
3. Click the Configuration tab.
4. Under Software, click Advanced Settings.
5. Under Net, select Net.MaxBeaconsAtOnce .
6. Change the value to 0.
   
   Note: The default is 100.
   
   
7. To apply the changes, reboot the ESXi/ESX host.
   

To disable transmission of Beacon Packets in the ESXi/ESX console:

1. Log in to ESXi/ESX host using an SSH client. For more information, see Connecting to an ESX host using an SSH client (1019852) or Tech Support Mode for Emergency Support (1003677).
2. Run this command:
   
   esxcfg-advcfg -s 0 /Net/MaxBeaconsAtOnce
   
   
3. To apply the changes, reboot the ESXi/ESX host.

Note: This is a global parameter so setting this to 0 stops beacon on all vmnics (regardless of the vSwitch Settings for Network Failover Detection).

Additional Information

In ESXi/ESX 4.1 and 5.x, Beacon Packets are sent only if both of these conditions are met:

• The vSwitch/Port Group is configured to use beacon probing for Network Failover Detection.
• The vSwitch/Port Group has more than one uplink.

Tech Support Mode for Emergency Support
What is beacon probing?
Connecting to an ESX host using an SSH client