Forum Discussion
NimbostratusMultiple 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 units are in the same subnet. The default gateway is set to 192.168.1.1, which is a VRRP address on the L3 side.
Since F5 devices synchronize route configurations across devices during config sync, any change to the routing table is applied to both units.
Given this, is it possible to configure different default gateways per device in an F5 HA pair? Specifically, I would like to set each unit's default gateway to the real IP of a different L3 device:
Default GW for L4 #1: 192.168.1.2
Default GW for L4 #2: 192.168.1.3
I'd like to hear the opinion of experts on whether this is possible and if there is a supported way to achieve this.
Thank you.
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.
3 Replies
f51Cumulonimbus
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.
- Injeyan_Kostas
Short answer is no, you can't have different default gateway in a HA setup.
Mike12345Altocumulus
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.
