hi all,
i would like to maintain my forum urls to the below structure.

forum.<sitename>.com = index page
forum.<sitename>.com/<category-name>/ = category page
forum.<sitename>.com/<category-name>/<forum>/ = forum page
forum.<sitename>.com/<category-name>/<forum>/<topic-name>.html = topic page

is this possible? how can i change/update in my forum. please advise me.