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CWaldon
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Jul 08, 2019

Changing subnet mask of ConfigSync/Failover Address

Hello,

 

I'm in the beginning stages of adding two new devices to an existing BIG-IP LTM cluster. When the initial two devices were configured the ConfigSync/Failover addresses were set up as a point-to-point (/30) subnet on a dedicated VLAN. I'd like to change the subnet mask of these addresses but the IPs will stay the same (e.g. 192.168.100.1/30 will become 192.168.100.1/29) so that there's room in the subnet for new IPs in order to add the two new devices into the cluster but I'm concerned that modifying the mask will cause a failover to trigger. These are production systems so I cannot failover unless I have an appropriate change window but I'm not sure if it's even necessary.

 

Does anyone know if this will cause a failover or flip the active/standby device?

  • Hi CWaldon,

     

    I just tested with a pair of virtual F5s and modifying the subnet of my configsync/failover IPs from 255.255.0.0 to 255.255.255.0 did not cause a fail over or any traffic disruption on that vlan. 

     

    Best,

    Andrew

  • Hi CWaldon,

     

    I just tested with a pair of virtual F5s and modifying the subnet of my configsync/failover IPs from 255.255.0.0 to 255.255.255.0 did not cause a fail over or any traffic disruption on that vlan. 

     

    Best,

    Andrew