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SmartConnect User’s Guide
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Chapter 3: Switch Virtualization BMD00082, February 2009
Switch failover is disabled by default, but can be enabled for any VSG. When enabled, switch
failover works as follows:
If some (or all) of the links fail in the failover trigger, the switch disables all internal ports
in the VSG. This causes the NIC team on the affected server blades to failover from the
primary to the backup NIC. This process is called a failover event.
When the appropriate number of links return to service, the switch enables the internal
ports in the VSG. This causes the NIC team on the affected server blades to fail back to the
primary switch (unless Auto-Fallback is disabled on the NIC team). The backup processes
traffic until the primary’s internal links come up, which takes up to five seconds.
Setting the Number of Links to Trigger Failover
The Number of Links to Trigger Failover specifies the minimum number of operational links
in the VSG that triggers a failover event. For example, if the limit is four, a failover event
occurs when the number of operational links in the trigger is four or fewer. If the trigger num-
ber is set to zero (0), the switch triggers a failover event only when no links in the VSG are
operational.
Configuring Switch Failover
Figure 3-B is a simple example of switch failover. One switch is the primary, and the other is
used as a backup. In this example, all external ports on the Primary Switch belong to a single
VSG with switch failover enabled, and the number of links to trigger failover set to two. If two
or fewer links in Trigger 1 remain active, the switch temporarily disables all internal server-
blade ports. This action causes a failover event on Server 1 and Server 2.
Figure 3-B Basic Switch Failover
On the BBI, choose Virtual Switch Groups > Settings to enable Switch Failover and to con-
figure the Number of Links to Trigger Failover.
Blade Server Chassis
Server 1
Server 2
Server 3
Server 4
Backup
Switch
Primary
Switch
VLAN 1:
VLAN 2:
Enterprise
Routing Switches
Trigger 1
Trigger 1
Internet