I see in the my routers settings under Protocol you have three settings Bridging PPPOE and Routing at the moment my HG612 is the modem and using Ethernet as broadband type on brightbox2 it's set to PPPOE, the way it's setup is this a form of bridging ?
Sorry if I waffle on about things that people already know but -
All bridging is from a network perspective is binding 2 or more networks or links together that otherwise would not be connected such that they will then be able to see each other completely and be unaware of the method used to bridge them, i.e. the bridge should be completely transparent to both sides of the bridge.
For example on a server or PC with multiple network ports, you can bind 2 or more of them together to form a bridge, those ports combine together to effectively create a switch, anything connected on those ports be it an entire network or just a singular device will be able to see each other (as long as they on the same VLAN), also in this case a virtual port is created so that the host device bridging the ports has an actual IP address to connect onto the bridge also, this is needed of course because all the physical ports on the bridge lose there IP addresses etc.
A wireless bridge is like connecting 2 switches together with an ethernet cable but the cable in this case is replaced by wireless signal and switches replaced by 2 access points acting in bridge mode, in this scenario there is technically a bridge at each end, each one allowing the bridging of the ethernet connected network to the wireless network, in the access point itself the wireless part and the ethernet part are bound together just like in the server/pc situation above and also like above a virtual port is created for the device to allow remote management via IP etc.
For DSL modems a true bridge is when the dsl and ethernet parts of the network just like above can see each other transparently without being aware of the bridge between them, but just like above the opposite can be true and that bridge can be broken and some modems can be configured to act like routers, for example the HG612 normally acts as a bridged modem but can be configured with custom firmware to act as a router with dhcp and dns and even a firewall etc.
And just like above a DSL router if it has a true bridge mode will do the exact same thing as the modem does albeit in the case of multi port routers then effectively have a switch connected to the modem, which depending on your ISP and whether or not you have dynamically assigned single or multiple IP, single static IP or multiple static IP may nor may not render the switch part useless or not
The only difference between most of these modems and combined modem/routers is the amount of hardware/firmware/software features and how well they are programmed.
And definitely agree on the fact that disabling a few features is not making a bridge mode as no adapters are bound together in such scenario. It is worth pointing out that when you bridge a modem/router, things like DHCP, DNS, Firewall cannot work any more because all these features require an actual IP Address which bridged part does not have any more, hence why modems such as the HG612 have a separate LAN port with a separate IP Address assigned to it so that configuration changes and firmware update can be made etc.
Hope this helps some people, although I don't consider myself a true expert on networking, I have been working as an IT consultant for nearly 17 years now and I find if you know the definitions of most things you can usually figure out what it is actually supposed to do