M.I.T = Multimedia IT dept.

1) Add the following lines /etc/pf.conf:

# enable queueing on the external interface to control traffic going to
# the Internet. use the priq scheduler to control only priorities. set
# the bandwidth to 610Kbps to get the best performance out of the TCP
# ACK queue.

altq on fxp0 priq bandwidth 610Kb queue { std_out, ssh_im_out, dns_out, \
tcp_ack_out }

# define the parameters for the child queues.
# std_out - the standard queue. any filter rule below that does not
# explicitly specify a queue will have its traffic added
# to this queue.
# ssh_im_out - interactive SSH and various instant message traffic.
# dns_out - DNS queries.
# tcp_ack_out - TCP ACK packets with no data payload.

queue std_out priq(default)
queue ssh_im_out priority 4 priq(red)
queue dns_out priority 5
queue tcp_ack_out priority 6

2) pfctl -f /etc/pf.conf

REFERENCES:
http://www.openbsd.org/faq/pf/queueing.html#example1