just for information. bigip is not like router/switch which forward/route traffic by default. listener object is required to pass traffic from one vlan to another vlan. there are 3 listener objects which are nat, snat and virtual server. you can use either one. nat and snat are source based listner object. virtual server is destination based listen object. the following sol talks about their precedence.
sol9038: The order of precedence for local traffic object listeners
http://support.f5.com/kb/en-us/solutions/public/9000/000/sol9038.html
hope this helps.
Nimbostratus
