Users Guide

11–QLogic Teaming Services
Teaming Mechanisms
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The actual assignment between adapters may change over time, but any protocol
that is not TCP/UDP based goes over the same physical adapter because only
the IP address is used in the hash.
Performance
Modern network interface cards provide many hardware features that reduce CPU
utilization by offloading specific CPU intensive operations (see “Teaming and
Other Advanced Networking Properties” on page 150). In contrast, the QLASP
intermediate driver is a purely software function that must examine every packet
received from the protocol stacks and react to its contents before sending it out
through a specific physical interface. Though the QLASP driver can process each
outgoing packet in near constant time, some applications that may already be
CPU bound may suffer if operated over a teamed interface. Such an application
may be better suited to take advantage of the failover capabilities of the
intermediate driver rather than the load balancing features, or it may operate more
efficiently over a single physical adapter that provides a specific hardware feature
such as Large Send Offload.
Types of Teams
Team types include switch-independent, switch dependent, and LiveLink.
Switch-Independent
The QLogic Smart Load Balancing type of team allows two to eight physical
adapters to operate as a single virtual adapter. The greatest benefit of the SLB
type of team is that it operates on any IEEE compliant switch and requires no
special configuration.
Smart Load Balancing and Failover
SLB provides for switch-independent, bidirectional, fault-tolerant teaming and load
balancing. Switch independence implies that there is no specific support for this
function required in the switch, allowing SLB to be compatible with all switches.
Under SLB, all adapters in the team have separate MAC addresses. The
load-balancing algorithm operates on Layer 3 addresses of the source and
destination nodes, which enables SLB to load balance both incoming and
outgoing traffic.
The QLASP intermediate driver continually monitors the physical ports in a team
for link loss. In the event of link loss on any port, traffic is automatically diverted to
other ports in the team. The SLB teaming mode supports switch fault tolerance by
allowing teaming across different switches- provided the switches are on the
same physical network or broadcast domain.