Same subnet on WAN and OPT for failover

marl_scot

Hi,
I have 2 fiber connections coming in, primary is 1G/1G and backup is 100M/100M
These are configured at the ISPs end as failover.
I have the Primary connected to WAN and the secondary connected to OPT on a SG3100 (21.05.1-RELEASE).
My ISP has given me the following details :

Primary :

Subnet : 109.200.200.152/29
MASK : 255.255.255.248
Network : 109.200.200.152
Gateway : 109.200.200.153
Usable IP : 109.200.200.154-158
Broadcast : 109.200.200.159

Backup :

Subnet : 109.200.200.152/29
MASK : 255.255.255.248
Network : 109.200.200.152
Gateway : 109.200.200.154
Usable IP : 109.200.200.155-158
Broadcast : 109.200.200.159

Using JUST the settings for Primary configured, i have nice fast 1G internet.
I just can't find a way to add the backup to my netgate.

After a lot of back and forth, they have said the interfaces should be configured as :
Primary :

IP : 109.200.200.156/29
GW : 109.200.200.155

Secondary :

IP : 109.200.200.157/29
GW : 109.200.200.155

Both with WAN configured using my original IPs as well as the new ones they gave me, I am unable to configure OPT to use the backup IP details. I keep getting an error about the subnet on OPT overlapping the WAN subnet.

Is anyone able to tell me what i am doing wrong? The ISP is insisting that (in general) having both primary and backup IPs in the same subnet should work.

viragomann

@marl_scot
The networks on different interfaces must not overlapping.
And I don't know any router which is capable to route with that settings.
Maybe the ISP can give some recommendations.

Two IPs within the same subnet with the same gateway is not a real failover set up for my understanding.

If the ISP refuses to change one of the subnets your only one option might be to put a router between the ISP and pfSense and nat the traffic to a different subnet.