6.0

Teaming and Failover Policy
NIC teaming lets you increase the network capacity of a virtual switch by including two or more physical
NICs in a team. To determine how the traffic is rerouted in case of adapter failure, you include physical
NICs in a failover order. To determine how the virtual switch distributes the network traffic between the
physical NICs in a team, you select load balancing algorithms depending on the needs and capabilities of
your environment.
NIC Teaming Policy
You can use NIC teaming to connect a virtual switch to multiple physical NICs on a host to increase the
network bandwidth of the switch and to provide redundancy. A NIC team can distribute the traffic between
its members and provide passive failover in case of adapter failure or network outage. You set NIC teaming
policies at virtual switch or port group level for a vSphere Standard Switch and at a port group or port level
for a vSphere Distributed Switch.
NOTE All ports on the physical switch in the same team must be in the same Layer 2 broadcast domain.
Load Balancing Policy
The Load Balancing policy determines how network traffic is distributed between the network adapters in a
NIC team. vSphere virtual switches load balance only the outgoing traffic. Incoming traffic is controlled by
the load balancing policy on the physical switch.
For more information about each load balancing algorithm, see the vSphere Networking publication.
Network Failure Detection Policy
You can specify one of the following methods that a virtual switch uses for failover detection.
Link status only
Relies only on the link status that the network adapter provides. Detects
failures, such as removed cables and physical switch power failures.
However, link status does not detect the following configuration errors:
n
Physical switch port that is blocked by spanning tree or is misconfigured
to the wrong VLAN .
n
Pulled cable that connects a physical switch to another networking
devices, for example, an upstream switch .
Beacon probing
Sends out and listens for Ethernet broadcast frames, or beacon probes, that
physical NICs send to detect link failure in all physical NICs in a team. ESXi
hosts send beacon packets every second. Beacon probing is most useful to
detect failures in the closest physical switch to the ESXi host, where the
failure does not cause a link-down event for the host.
Use beacon probing with three or more NICs in a team because ESXi can
detect failures of a single adapter. If only two NICs are assigned and one of
them loses connectivity, the switch cannot determine which NIC needs to be
taken out of service because both do not receive beacons and as a result all
packets sent to both uplinks. Using at least three NICs in such a team allows
for n-2 failures where n is the number of NICs in the team before reaching an
ambiguous situation.
Chapter 22 Networking Policies
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