Switch-assiste
dLoadBalancingwithFaultTolerance(SLB)
Switch-assiste
d Load Balancing with Fault Tolerance (SLB) is a team type that allows full transmit and
receive load ba
lancing. SLB requires the use of a switch that suppor ts some form of Port Trunking (for
example, EtherChannel, MultiLink Trunking, and so on). SLB d oes not support switch redundancy since all
ports in a team must be connected to the same switch. S LB is similar to the 802.3ad Dynamic team type
discussed late
r.
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 traffic. 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 LA N. With TLB, trafficreceivedbytheserveris
not load balanced. The primary teamed port is responsible for receiving all traffic 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 team
ed ports should b e the Primar y team ed port. This ability is important in environments where
one or more teamed ports are more p referred tha n other ports in the same team. The nee d for ranking
certain team ed por ts better than others can be a result of une qual speeds, better adapter capabilities (for
example, higher receive/transmit descriptors or buffers, interrupt coalescence, and so on), or p reference
for the team’s Primary port to be located on a specificswitch.
Network Fault Tolerance Only (NFT)
Network Fault Tolerance (NFT) is the foundation of HP P roLiant N etwork Adapter Teaming. In NFT mode,
from two to eight teamed p orts 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-Primar y teamed ports remain idle
unless the Primary teamed port fails. All teamed ports may transmit and receive he artbeats, including
Non-Primary adapters.
The fault-tolerance feature tha t NFT represents for HP P roLiant Network Adapter Teaming is the only
feature found in every other team t ype. It can be said that the foundation of every team type supports NFT.
Network Fault Tolerance Only with Preference Order
Network Fault T olerance Only with Preference Order is identical in almost every way to NFT . The only
diffe
rence is that this team type allows the server administrator to prioritize the order in which teamed
ports should be the Primary team ed 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 team e d
ports better than others can be a result of unequal speeds, better adapter capabilities (for example,
high
er receive/transmit descriptors or buffers, interrupt coalescence, and so on), or preference for the
tea
m’s P rimary port to be located on a specificswitch.
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 bala ncing
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
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