HP ProLiant DL380 G5 DPSS, Administration Manual

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Switch-assisted Load Balancing with Fault Tolerance (SLB)
Switch-assisted Load Balancing with Fault Tolerance (SLB) is a team type that allows full transmit and
receive load balancing. SLB requires the use of a switch that supports some form of Port Trunking (for
example, EtherChannel, MultiLink Trunking, and so on). SLB does not support switch redundancy since all
ports in a team must be connected to the same switch. SLB is similar to the 802.3ad Dynamic team type
discussed later.
Transmit Load Balancing with Fault Tolerance (TLB)
Transmit Load Balancing with Fault Tolerance (TLB) is a team type that allows the server to load balance
its transmit traf fi c. TLB is switch independent and supports switch fault tolerance by allowing the teamed
ports to be connected to more than one switch in the same LAN. With TLB, traf fi c received by the server is
not load balanced. The primary teamed port is responsible for receiving all traf fi c destined for the server.
In case of a failure of the primary teamed port, the NFT mechanism ensures connectivity to the server
is preserved by selecting another teamed port to assume the role.
Transmit Load Balancing with Fault Tolerance and Preference Order
Transmit Load Balancing with Fault Tolerance and Preference Order is identical in almost every way to
TLB. The only difference is that this team type allows the server administrator to prioritize the order in
which teamed ports should be the Primary teamed port. This ability is important in environments where
one or more teamed ports are more preferred than other ports in the same team. The need for ranking
certain teamed ports better than others can be a result of unequal speeds, better adapter capabilities (for
example, higher receive/transmit descriptors or buffers, interrupt coalescence, and so on), or preference
for the team’s Primary port to be located on a speci fi c switch.
Network Fault Tolerance Only (NFT)
Network Fault Tolerance (NFT) is the foundation of HP ProLiant Network Adapter Teaming. In NFT mode,
from two to eight teamed ports are teamed together to operate as a single virtual network adapter.
However, only one teamed port—the Primary teamed port—is used for both transmit and receive
communication with the server. The remaining adapters are considered to be stand-by (or secondary
adapters) and are referred to as Non-Primary teamed ports. Non-Primary teamed ports remain idle
unless the Primary teamed port fails. All teamed ports may transmit and receive heartbeats, including
Non-Primary adapters.
The fault-tolerance feature that NFT represents for HP ProLiant Network Adapter Teaming is the only
feature found in every other team type. It can be said that the foundation of every team type supports NFT.
Network Fault Tolerance Only with Preference Order
Network Fault Tolerance Only with Preference Order is identical in almost every way to NFT. The only
difference is that this team type allows the server administrator to prioritize the order in which teamed
ports should be the Primary teamed port. This ability is important in environments where one or more
teamed ports are more preferred than other ports in the same team. The need for ranking certain teamed
ports better than others can be a result of unequal speeds, better adapter capabilities (for example,
higher receive/transmit descriptors or buffers, interrupt coalescence, and so on), or preference for the
team’s Primary port to be located on a speci
fi c switch.
Transmit load balancing methods (algorithms)
All load-balancing team types (TLB, SLB, 802.3ad Dynamic, and Dual Channel) load balance transmitted
frames. There is a fundamental decision that must be made when determining load balancing
mechanisms: whether or not to preserve frame order.
Frame order preservation is important for several reasons—to prevent frame retransmission because
frames arrive out of order and to prevent performance-decreasing frame reordering within OS protocol
stacks. In order to avoid frames from being transmitted out of order when communicating with a target
network device, the team’s load-balancing algorithm assigns outbound conversations to a particular
HP ProLiant DL380 G5 Storage Server 149