17–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
use by offloading certain CPU intensive operations (see
Advanced Networking Properties” on page 298
). In contrast, the ASP 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
particular physical interface. Though the ASP 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 particular hardware feature such as Large
Send Offload.
Types of Teams
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 ASP 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.
Summary of Contents for 8400 Series
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