Comparing the Difference Between Self-IP and Floating IP in the F5

cowboyF5 LTM Technology

To start, it’s easier to explain what a Self IP address does on an F5

Self IP Address

  • Self IP address is the IP address that is used to preform the monitoring in F5.
  • Once you enable Monitors for the Pool members in F5 then source IP address is F5 self IP address and destination IP address is Pool Member IP address.
  • For every VLAN you need to create a separate Self IP address in each of the F5 devices if you are using active/passive or Active/Active in HA.
  • Self IP address will be different fro each F5 device if you are using active/passive or Active/Active HA.
  • In Simple terms, the Self IP address is the Interface IP address that is configured in HSRP/VRRP for Cisco Routers.
  • Self IP address will be assigned to the default traffic group (traffic-group-local-only), if you do not create any other traffic groups.
  • Each and every Self IP address that you create on the F5 automatically gets the MAC address from the Pool.

Floating Self IP address

  • Floating Self IP address is used to initate the traffic to backend servers or pool members if the SNAT automap is used.
  • For every VLAN you need to create the same Floating Self IP address in each of the F5 devices if you are using active/passive or Active/Active HA.
  • Floating Self IP address wil be the same in both of the F5 devices if you are using active/passive or Active/Active HA.
  • In Simple terms, Floating Self IP address is the Virtual IP address that is configured in HSRP/VRRP for Cisco Routers
  • Floating Self IP address will be assigned to the default traffic group (traffic-group-1), if you do not create any other traffic groups.
  • Each and every Self IP address that you create on the F5 automatically gets the MAC address from the Pool.

NOTES

The non-floating self ips on both big-ips will need access to the backend pool members for health monitoring.

The floating self ips, if configured and using SNAT Automap, for example, will be used for application traffic so may also need firewall rules in place. So floating self ips can be used for servers’ default gateways in an inline setup and/or the source address of incoming client traffic if the servers’ default gateways is not the bigips.

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