Babylon 5, as well as most Earth installations and capital ships, have a complex defense grid in addition to several Star Fury squadrons to fend off attackers. Not only does the grid include offensive weaponry, but also interceptors to stop enemy fire from reaching its intended target.
Babylon 5 received a new defense grid within the past year, so we'll examine the one that is currently on the station.
Anti-Ship
Cannon
Anti-Ship Cannon Firing 
Anti-Fighter
Gun
Anti-Fighter Gun Firing 