Fortigate HA Back-to-Back Gotchas

Recently, I had a customer that deployed two sets of HA Fortigates at two separate locations. Additionally, the customer had three Layer 2 Circuits between the sites (200Mbps, 100Mbps and 10Mbps respectively). They were two sets of Fortigate 200E. We were getting all sorts of strange issues with OSPF and overall connectivity. We started a packet capture on one site and pinged across. We got responses but did not see the packets hitting our interface (locally attached). I wanted to see if we were seeing the MAC address of the remote Fortigate or the carrier’s equipment. Low and behold, the two sets of clusters were using the SAME virtual MAC address. By default, when you create the HA cluster, if you do not change the group id, the will use ‘0’ and they will all have the same MAC address.

port10 (00:09:0F:09:00:0D)
port10 (00:09:0F:09:00:0D)

Both firewalls were using port 10 to connect to each location. As you can see above, both port 10’s had the exact same MAC address.

get hardware nic port10

By running the command above, you will be able to see the “real” MAC address and the virtual one being used.

Description :FortiASIC NP6LITE Adapter
Driver Name :FortiASIC NP6LITE Driver
PCI Slot :PCI Bus 0000:06
irq :19
Board :200E
lif id :1
lif oid :65
netdev oid :65
Current_HWaddr 00:09:0f:09:00:0d
Permanent_HWaddr 70:<REMOVED>:07
========== Link Status ==========
Admin :up
netdev status :up
autonego_setting:0
link_setting :1
speed_setting :100
duplex_setting :1
Speed :100
Duplex :Full
link_status :Up
============ Counters ===========
Rx Pkts :15875
Rx Bytes :2630190
Tx Pkts :22792
Tx Bytes :1532910
Host Rx Pkts :15875
Host Rx Bytes :2407940
Host Tx Pkts :22792
Host Tx Bytes :1532910
Host Tx dropped :0

To fix this issues, you need to issue the following command on both boxes:

config system ha
set group-id 2
end

 

This will create a different MAC address. DO NOT USE THE SAME NUMBER as you will have the same issues I experienced.

You can check out the article using the following link.