1. A vision system of a vehicle, said vision system comprising: a plurality of cameras disposed at a vehicle and having respective fields of view exterior of the vehicle; wherein said plurality of cameras comprises a forward viewing camera having at least a forward field of view forward of the vehicle, a rearward viewing camera having at least a rearward field of view rearward of the vehicle, a driver-side sideward viewing camera having at least a sideward field of view at the driver side of the vehicle and a passenger-side sideward viewing camera having at least a sideward field of view at the passenger side of the vehicle; an image processing system operable to process image data captured by said plurality of cameras; wherein, responsive to processing of captured image data, said vision system is operable to synthesize a composite image derived from image data captured by said plurality of cameras; wherein one of said plurality of cameras functions as a master camera and other cameras of said plurality of cameras function as slave cameras, and wherein said vision system, responsive to processing of image data captured by the master camera, determines operating parameters for the master camera; wherein the determined operating parameters for the master camera are used by the other cameras of said plurality of cameras; wherein said cameras capture image data for a bird's-eye view display system of the vehicle; wherein each of said cameras is connected via network connection to a vehicle network, and wherein the vehicle network is selected from the group consisting of (i) a CAN bus, (ii) a LIN bus, (iii) an Ethernet bus, (iv) a wireless network and (v) a UART connection; wherein topology of said network connection comprises star topology or daisy chain topology; wherein a network hub routes commands from the master camera to the slave cameras; wherein said network hub is part of one of (i) a multi-camera electronic control unit, (ii) a vehicle electronic control unit and (iii) the master camera; and wherein, during a reversing maneuver of the vehicle, said vision system selects the rearward viewing camera as the master camera, and wherein, during a forward driving maneuver of the vehicle, said vision system selects the forward viewing camera as the master camera.