Fortinet 5003 - Manual (Page 77)

FortiGate-5140 and 5050 base backplane communication Base backplane HA configurations
FortiSwitch-5003A and 5003 Fabric and Base Backplane Communications Guide
01-30000-85717-20081205
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• If interface priorities are not all equal, set the base backplane interface priority
to a higher value than all other interfaces.
• If interface priorities are all equal, set the base backplane interface priority to a
higher value than all other interfaces, or disable interfaces listed above the
base backplane interface in the Heartbeat Interface list. For some FortiGate
models, FortiSwitch slot positions, or configurations of other HA interfaces, this
may mean that no change is required.
8 Select OK.
Choosing the slot position
Depending on the types of communications, HA or other, that you want to pass
through the base channels, you may choose to install FortiSwitch boards in
different slots: base hub/switch slot 1, base hub/switch slot 2, or both.
When using FortiSwitch boards to provide a network connection to the base
channels, hub/switch slot position does not matter. However, you can improve
robustness by installing FortiSwitch boards in both slots and providing a
redundant link.
For all types of communication, using both slots has the advantage of improving
reliability of communications through or to the base backplane because no
FortiSwitch is a single point of failure. Using both slots also provides the option of
separating multiple sensitive or high volume communications, such as HA
communications for multiple clusters.
However, if you install only one FortiSwitch board, in addition to fault tolerance
considerations, the slot position has additional effects specific to HA.
• Inter-chassis HA configurations require that the switch use the same slot
number in each chassis so that each cluster member’s configuration uses the
same heartbeat interface.
• Slot position affects HA heartbeat interface selection and failover order.
Slot position and HA heartbeat interface precedence
When installing only one FortiSwitch board with an HA cluster of FortiGate-5001A
or FortiGate-5005FA2 boards, it is usually preferable to use hub/switch slot 1. This
allows you to connect one or more of the other FortiGate-5001A or
FortiGate-5005FA2 interfaces as backup HA heartbeat interfaces.
The preferred FortiSwitch board slot is different for FortiGate-50051SX and
FortiGate-5001FA2 board HA clusters. In this case, it is usually preferable to use
hub/switch slot 2.
The reason for selecting different slots is related to the mechanism for heartbeat
interface selection, which is indirectly tied to slot number.
During heartbeat interface selection, the heartbeat interface with the highest
priority is selected first. If multiple heartbeat interfaces have highest priority,
including when all have equal priority, the HA cluster chooses a heartbeat
interface using the Heartbeat Interface list.
Note: For HA configurations, you can further improve fault tolerance by adding one or more
non-base backplane interfaces as heartbeat interface failovers.