ALTQ - Allocation By Percentage

example swiped from

altq on $ext_if cbq bandwidth 640Kb queue { def, ftp, udp, \
    http, ssh, icmp }
    queue def bandwidth 18% cbq(default borrow red)
    queue ftp bandwidth 10% cbq(borrow red)
    queue udp bandwidth 30% cbq(borrow red)
    queue http bandwidth 20% cbq(borrow red)
    queue ssh bandwidth 20% cbq(borrow red) { ssh_interactive, \
          ssh_bulk }
          queue ssh_interactive priority 7 bandwidth 20%
          queue ssh_bulk priority 0 bandwidth 80%
    queue icmp bandwidth 2% cbq

pass log quick on $ext_if proto tcp to port ssh \
    queue (ssh_bulk, ssh_interactive)
pass in quick on $ext_if proto tcp to port ftp queue ftp
pass in quick on $ext_if proto tcp to port www queue http
pass out on $ext_if proto udp all queue udp
pass out on $ext_if proto icmp all queue icmp