Differences between the bridging mode and the routing mode

hello .

bridge mode you can consider the ONT as one switch , it works in L2 ,no route function , PC or other terminal obtain IP from uplink DHCP server ,the ONT only forward the packets .

in the route mode , LAN side network you can control by your self , PC or other terminal obtain ip from the router , in this mode ,the ONT can be consider as one router .

by the way , not all the ONT support route mode .

Bridge Mode:You can create HTTP and HTTPS services only.
You cannot configure Network ACL, Source NAT or Destination NAT in this mode.
Instant SSL, etc., are not available in this mode.
Fewer network changes are required since the existing IP Address infrastructure is reused.
Features like Hardware bypass and bypass on failure are only available in this mode.
In bridge mode, services not configured as VIP are allowed to pass through the box by default.

 Routed Mode:

in such an arrangement, the firewall works as a Layer 3 element (much like a router) from the perspective of hosts connecting to it. Each of its interfaces is assigned to a different logical subnet and the packets are conditionally routed between them. In the reference scenario, the inside interface has the IP address 192.168.2.2, whereas the outside uses the address 172.20.20.2. Considering that the hosts are interconnected by the firewall, machines on the inside need to configure the address 192.168.2.2 as their L3 gateway in order to reach outside destinations.