Configuration eBGP // HA cluster //

[khaled88]

Hello,

I have a BGP flapping issue between two Fortigate ISPs in standalone mode and my Fortigate firewall in HA mode. I need your help, and could you please provide the recommended configuration?

Thank you.

[Toshi_Esumi]

If disabling BFD changes the situation, the problem is on the other end. Check if it's even configured.
The command to see the BFD neighbor status seems to be
   "get router info bfd neighbor"

Toshi

[khaled88]

Hello, 

I'm sorry for the delay, the same problem when we disabling the BFD. 

KH

[Toshi_Esumi]

As I said previously, check the status of the other end. You need to troubleshoot with the ISP. At that time, you could open a ticket at TAC and co-op troubleshoot among them.

Toshi

[khaled88]

Hello, 

Thank you for your response. 

Bellow the configuration for the Other End : 
config router bgp
set as "public AS"
set router-id X.X.X.X
set holdtime-timer 240
edit "172.16.20.35"
set soft-reconfiguration enable
set prefix-list-in "PREFIXES_IN"
set prefix-list-out "PREFIXES_OUT"
set remote-as "Private_AS"

[Toshi_Esumi]

As you see BFD is not set. So leave it out on local end. And subnets are different (192.168.20.x and 172.16.20.35). There must be a routing device in between.
This troubleshooting requires getting in the FGTs and see what's going on then test something, which can't do over community posts. You have to open a ticket at TAC then let the TAC person to examine and troubleshoot this.

Toshi