Installation guide

CHAPTER 11 Networking
373
Using Virtual Switches
ESX Server allows you to create abstracted network devices called virtual ethernet
switches. Each virtual switch is a network hub that can be used by virtual machines. A
virtual switch can route traffic internally between virtual machines, or link to external
networks.
Virtual switches can be used to combine the bandwidth of multiple network adapters
and balance communications traffic among them. They can also be configured to
maintain persistent network connections despite link failures for individual adapters.
A virtual switch models a physical ethernet switch. A virtual switch contains 32 logical
ports. You can connect one network adapter of a virtual machine to each port.
Each virtual switch can also have one or more port groups assigned to it. For more
information on port groups, see Creating Port Groups on page 220.
Choosing a Network Label
ESX Server uses network labels to represent network connections to virtual machines.
The network label is intended to be a functional descriptor for the network
connection. ESX Server represents both virtual switches and port groups to virtual
machines by assigning them a network label.
You can only change the network label for a switch when it is not being used by a
virtual machine.
Binding Physical Adapters
You can group physical adapters by “binding” them together. This is the functional
equivalent for NIC teaming in ESX Server. Certain options you can configure through
the Service Console refer to grouped adapters as a “bond”.
You should bind together similar physical adapters whenever possible. ESX Server
uses only features or capabilities common to all adapters when defining the
functionality of a bonded switch. For example, ESX Server can use a hardware
acceleration feature for a bond only if all adapters in the bond include that feature.
Hardware acceleration features supported by ESX Server include:
• VLAN tag handling
• Checksum calculations
• TCP Segmentation Offloading
Binding together identical models of physical adapters ensures that all features of the
adapter can be used by ESX Server.