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Table of Contents

FortiGate-6000 Handbook

Controlling SNAT port partitioning behavior

You can use the following command to control how the FortiGate-6000 partitions source NAT (SNAT) source ports among FPCs:

config load-balance setting

set nat-source-port {chassis-slots | enabled-slots}

end

chassis-slots this option statically allocates SNAT source ports to all FPCs. The source port distribution is not affected by whether or not an FPC goes down, is disabled, or is taken offline for maintenance or some other purpose.

If an FPC goes down, is disabled, or is taken offline, the SNAT source ports assigned to that FPC will not be re-allocated to the FPCs that are still operating. Fewer source ports will be available, but all FPCs that are still operating will maintain the same SNAT source port allocation and active sessions being processed by the still operating FPCs will not be affected.

enabled-slots SNAT source port partitioning dynamically distributes SNAT source ports to operating FPCs. This is the default behavior and is recommended in most cases.

If an FPC goes down, is disabled, or is taken offline for maintenance or some other purpose, SLBC dynamically re-allocates SNAT source ports among the remaining FPCs. This means that all configured SNAT source ports remain available. If SNAT source ports are re-allocated when the FortiGate-6000 is actively processing traffic, some active sessions may be lost if their source ports are allocated to different FPCs.

Controlling SNAT port partitioning behavior

You can use the following command to control how the FortiGate-6000 partitions source NAT (SNAT) source ports among FPCs:

config load-balance setting

set nat-source-port {chassis-slots | enabled-slots}

end

chassis-slots this option statically allocates SNAT source ports to all FPCs. The source port distribution is not affected by whether or not an FPC goes down, is disabled, or is taken offline for maintenance or some other purpose.

If an FPC goes down, is disabled, or is taken offline, the SNAT source ports assigned to that FPC will not be re-allocated to the FPCs that are still operating. Fewer source ports will be available, but all FPCs that are still operating will maintain the same SNAT source port allocation and active sessions being processed by the still operating FPCs will not be affected.

enabled-slots SNAT source port partitioning dynamically distributes SNAT source ports to operating FPCs. This is the default behavior and is recommended in most cases.

If an FPC goes down, is disabled, or is taken offline for maintenance or some other purpose, SLBC dynamically re-allocates SNAT source ports among the remaining FPCs. This means that all configured SNAT source ports remain available. If SNAT source ports are re-allocated when the FortiGate-6000 is actively processing traffic, some active sessions may be lost if their source ports are allocated to different FPCs.