Technical Tip: Assign the Interfaces on FortiGate-VM in AWS Cloud

[KumarV]

Description	This article describes how to assign the Interfaces on FortiGate-VM in AWS Cloud. This topology has been created to achieve: Public_FG1 -->Port1 an IP from 10.1.1.0/24 Private_FG1-->Port2 an IP from 10.1.2.0/24 HA_FG1       -->Port3 an IP from 10.1.3.0/24 Mgmt_FG1   -->Port4 an IP from 10.1.4.0/24 Port3  is getting the IP from 10.1.4.0/24 Port4  is getting the IP from 10.1.3.0/24
Scope	FortiGate-VM AWS Cloud.
Solution	The reason behind this issue is that AWS assigns the Ports in increasing order which means if the Mgmt_FG1 is attached before HA_FG1 then AWS will map Mgmt_FG1 to port3 and HA_FG1 to Port4. So it is important to follow the correct order while associating the Network interfaces to FortiGate-VM Instance. It will be necessary to first attach the HA_FG1 which has subnet 10.1.3.0/24 to the Instance so that AWS assigns it to Port3 And then to Mgmt_FG1 which has 10.1.4.0/24 subnet to Port4. Steps to follow: Detach HA_FG1 and Mgmt_FG1 from Fortigate VM Instance. Attach HA_FG1 first and then Mgmt_FG1: In the picture below, it is possible to se: Port3 is getting IP from 10.1.3.0/24 subnet Port4 is getting IP from 10.1.4.0/24 subnet