6.5.1

Table Of Contents
n
Protect the environment from DoS attacks in any case by activating the BPDU filter on the ESXi host
or on the physical switch.
n
On a host running ESXi 4.1 Update 3, ESXi 5.0 Patch 04 and later 5.0 releases, and ESXi 5.1
Patch 01 and later, enable the Guest BPDU filter in one of the following ways and reboot the host:
n
In the Advanced System Settings table on the Configure tab for the host in the
vSphere Web Client, set the Net.BlockGuestBPDU property to 1.
n
In an ESXi Shell to the host, type the following vCLI command:
esxcli system settings advanced set -o /Net/BlockGuestBPDU -i 1
n
On a host that does not have the Guest BPDU filter implemented enable the BPDU filter on the
physical switch port to the virtual bridge device.
Network Device Configuration
Distributed or
standard switch
Set the Forged Transmit property of the security policy on the port group to Reject.
Physical switch
n
Keep the Port Fast configuration.
n
Enable the BPDU filter on the individual physical switch port. When a BPDU frame arrives at
the physical port, it is filtered out.
Note Do not enable the BPDU filter globally. If the BPDU filter is enabled globally, the Port Fast
mode becomes disabled and all physical switch ports perform the full set of STP functions.
Low Throughput for UDP Workloads on Windows Virtual
Machines
When a Windows virtual machine in vSphere 5.1 and later transmits large UDP packets, the throughput is
lower than expected or is oscillating even when other traffic is negligible.
Problem
When a Windows virtual machine transmits UDP packets larger than 1024 bytes, you experience lower
than expected or oscillating throughput even when other traffic is negligible. In case of a video streaming
server, video playback pauses.
Cause
For every UDP packet larger than 1024 bytes, the Windows network stack waits for a transmit completion
interrupt before sending the next packet. Unlike for earlier releases, vSphere 5.1 and later releases do not
provide a transparent workaround of the situation.
vSphere Troubleshooting
VMware, Inc. 97