6.0.1

Table 1‑118. Data Counters
Chart Label Description
Packets Transmitted Number of network packets transmitted across the top ten virtual NIC instances on
the virtual machine. The chart also displays the aggregated value for each NIC.
n
Counter: packetTx
n
Stats Type: Absolute
n
Unit: Number
n
Rollup Type: Summation
n
Collection Level: 3
Packets Received Number of network packets received across the top ten virtual NIC instances on the
virtual machine. The chart also displays the aggregated value for each NIC.
n
Counter: packetRx
n
Stats Type: Absolute
n
Unit: Number
n
Rollup Type: Summation
n
Collection Level: 3
Chart Analysis
Network performance depends on application workload and network configuration. Dropped network
packets indicate a bottleneck in the network. To determine whether packets are being dropped, use esxtop
or the advanced performance charts to examine the droppedTx and droppedRx network counter values.
If packets are being dropped, adjust the virtual machine shares. If packets are not being dropped, check the
size of the network packets and the data receive and transfer rates. In general, the larger the network
packets, the faster the network speed. When the packet size is large, fewer packets are transferred, which
reduces the amount of CPU required to process the data. When network packets are small, more packets are
transferred but the network speed is slower because more CPU is required to process the data.
NOTE In some instances, large packets might result in high network latency. To check network latency, use
the VMware AppSpeed performance monitoring application or a third-party application.
If packets are not being dropped and the data receive rate is slow, the host is probably lacking the CPU
resources required to handle the load. Check the number of virtual machines assigned to each physical NIC.
If necessary, perform load balancing by moving virtual machines to different vSwitches or by adding more
NICs to the host. You can also move virtual machines to another host or increase the host CPU or virtual
machine CPU.
If you experience network-related performance problems, also consider taking the actions listed below.
Table 1‑119. Networking Performance Enhancement Advice
# Resolution
1 Verify that VMware Tools is installed on each virtual machine.
2 If possible, use vmxnet3 NIC drivers, which are available with VMware Tools. They are optimized for high
performance.
3 If virtual machines running on the same host communicate with each other, connect them to the same vSwitch to
avoid transferring packets over the physical network.
4 Assign each physical NIC to a port group and a vSwitch.
5 Use separate physical NICs to handle the different traffic streams, such as network packets generated by virtual
machines, iSCSI protocols, vMotion tasks.
6 Ensure that the physical NIC capacity is large enough to handle the network traffic on that vSwitch. If the capacity
is not enough, consider using a high-bandwidth physical NIC (10Gbps) or moving some virtual machines to a
vSwitch with a lighter load or to a new vSwitch.
7 If packets are being dropped at the vSwitch port, increase the virtual network driver ring buffers where applicable.
vSphere Monitoring and Performance
84 VMware, Inc.