Interface mode bridge

Question

Good morning and thank you in advance. 
 Someone could explain: 
 What is it and what are the interfaces in bridge mode for? 
 You can find it in the section Network - Interfaces - Add Interface - Add bridge. 
 Since the first time you start and configure the Sophos XG Firewall, it automatically assigns 3 ports for the LAN zone, the port1 -port3 and port4 and creates an interface in bridge mode (br0) for the 3 physical ports. 
 In addition, port3 and por4 cannot be unlinked, leaving only port 1 for the LAN zone. 
 In summary I would like to know a little more or why sophos creates this configuration. 
 Thank you very much again

LuCar Toni · Answer

Bridges are basically a Ethernet Bridge. 
 https://en.wikipedia.org/wiki/Bridging_(networking) 
 With all his "features" and modes, on the kernel, it is the same mechanism. 
 You are basically expanding your network and building up a Switch. 
 XG wizard does that, to simplify the on boarding process, because it will bridge the interfaces, which you selected, into one bridge. So you get the same IP, no matter what interface you plugged in. 
 You should be able to simply unlink the Bridge interface (which you are not connected to). Means, you are connected to Port1, you should be able to unbind Port3/4 and have only Port1 in the bridge. Afterwards you should be able to delete the bridge. 
 Best way to delete the bridge is by coming from WAN (Or Central Management: https://community.sophos.com/kb/en-us/133432 )

rfcat_vk · Answer

Hi, 
 the bridge mode was configured during installation because you told it too. If you don't want bridge mode you tick the route mode box. 
 If you want access to the ports in the bridge you need to delete the bridge. 
 Ian