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minheo's avatar
minheo
Icon for Nimbostratus rankNimbostratus
Jun 11, 2025
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Multiple Default Gateways

Hi,   I have a question regarding default gateway configuration. Please refer to the following setup:     We currently have an L4 HA device setup (R2600) in Active-Standby mode, and both uni...
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  • VGF5's avatar
    VGF5
    Jun 11, 2025

    Hi minheo​ 

    It is not possible or supported to configure different default gateways per device in an F5 HA pair (BIG-IP tenants on rSeries/F5OS). The default gateway must be the same on both units, and any change will be synchronized across the HA pair. The supported method for gateway redundancy is to use a floating IP (VRRP/HSRP) on the upstream L3 device.

     

Mike12345's avatar
Mike12345
Icon for Altocumulus rankAltocumulus
Jun 15, 2025

Assuming you're trying to optimise traffic flow in the event of the primary F5 failing.

Lets assume you run HSRP/VRRP as your HA protocol on the LAN. Then you could set up IP SLA L3#1 to track the availability of L4#1 (.5)
L3#1 sends PING request to L4#1 (.5). If the responses stop then the IP SLA object is set to false. This will then trigger :3#1 to lower its HSRP priority and L3#2 will take over ownership of the .1 IP address.

You can also use the IP SLA tracking object to change the OSPF / BGP metrics so that traffic will prefer to route to L3#2 in the reverse direction.

Its not a complex operation. just have a chat with your friendly neighbourhood network engineer.