Checking the bridging information in transparent mode

Checking the bridging information is useful when you are experiencing connectivity problems. When FortiGate is set to transparent mode, it acts like a bridge and sends all incoming traffic out on the other interfaces. Each bridge is a link between interfaces.

When traffic is flowing between the interfaces, you can see the bridges listed in the CLI. If no bridges are listed, this is the likely cause of the connectivity issue. When investigating bridging information, check for the MAC address of the interface or device in question.

How to check the bridging information

To view the list of bridge instances in the CLI:

diagnose netlink brctl list

Sample output:

#diagnose netlink brctl list

list bridge information

1. root.b fdb: size=256 used=6 num=7 depth=2 simple=no

Total 1 bridges

How to display forwarding domain information

You can use forwarding domains, or collision domains, in routing to limit where packets are forwarded on the network. Layer 2 broadcasts are limited to the same group. By default, all interfaces are in group 0. For example, if the FortiGate has 12 interf