Network Connectivity Issues with Virtual Network Adapters in Promiscuous Mode

Products

• VMware vSphere ESXi

Issue/Introduction

A  network sniffer inside the guest operating system or have an application, service, or driver that puts the virtual network adapter into promiscuous mode. The following symptoms are seen.

• Virtual machine does not reply to multicast or broadcast pings.
• Guest operating system is not receiving ARP requests. Unable to ping the virtual machine from a different machine. However, the other machine is pingable from the VM.
• Once the other machine is pinged from the VM, the VM gains connectivity.
• The guest operating system is not receiving a DHCP response from the DHCP server or is unable to renew a DHCP lease.
• The DHCP server on the virtual machine is not receiving DHCP requests and is not leasing IP addresses.
• The sniffer doesn't detect any broadcast or multicast packets.

 

Environment

VMware ESXi 7.x

VMware ESXi 8.x

Resolution

If you run a network packet sniffer or other application inside the guest operating system that puts the virtual network adapter into promiscuous mode, your guest operating system may not receive multicast and broadcast frames if you do not have the virtual switch configured in promiscuous mode.

To use a virtual network adapter in promiscuous mode, you must also put the virtual switch to which it connects in promiscuous mode. For more information, see Configuring promiscuous mode on a virtual switch or portgroup (1004099).

Note: In the guest operating system, bring down and bring back up the virtual network adapter to have the changes take effect. If your virtual machine is running Windows NT 4, you must reboot the virtual machine.