Autodeploy ESXi host fails to boot intermittently with error "Could not chain image: Connection timed out"

Products

• VMware vCenter Server
• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• ESXi hosts fail to boot from Autodeploy with the error on the console:
  
  

Could not chain image: Connection timed out

Fatal error: 34 (Unexpected EOF)

• The management network that ESXi host boots from is shared with other multicast traffic.

Environment

VMware vSphere ESXi 5.1
VMware vSphere ESXi 5.5
VMware vCenter Server 6.0.x
VMware vCenter Server 5.1.x
VMware vCenter Server 5.5.x
VMware vSphere ESXi 6.0

Cause

iPXE acknowledges multicast traffic by default. If there is a large amount of multicast traffic, it slows down iPXE causing connections to time out.

Resolution

This issue is resolved in vCenter Server 5.5 Update 3 and 6.0. These versions include a new version of iPXE that has multicast turned off.

To resolve the issue:

1. Replace the default iPXE (undionly.kpxe.vmw-hardwired) with the iPXE version that has multicast turned off (undionly.kpxe.vmw-hardwired-nomcast) on the TFTP Server. For more information, see VMware vSphere 6.0 Documentation Center.
   
2. Ensure that the DHCP reference is updated to point to the new name of iPXE.