Bridge and ZP IP addresses

hi board
as i believed until now, sonos bridge sets up an own sonos network while connected to a router.

but, as my WLAN/router assigns IP addresses to bridge and zone players (and not the bridge as expected) i am some how confused.
i thought this would be taken over by sonos bridge.

does the bridge do the streaming on a parallell wlan and uses ip addresses of my router ?
what happens if i deny fetching IP's for zone players? will bridge take that over then?

thanks for help