# $OpenBSD: ackpri,v 1.2 2003/03/10 14:24:33 henning Exp $ # $DragonFly: src/share/examples/pf/ackpri,v 1.1 2005/12/13 01:58:27 corecode Exp $ # Use a simple priority queue to prioritize empty (no payload) TCP ACKs, # which dramatically improves throughput on (asymmetric) links when the # reverse direction is saturated. The empty ACKs use an insignificant # part of the bandwidth, but if they get delayed, downloads suffer # badly, so prioritize them. # Example: 512/128 kbps ADSL. Download is 50 kB/s. When a concurrent # upload saturates the uplink, download drops to 7 kB/s. With the # priority queue below, download drops only to 48 kB/s. # Replace lo0 with your real external interface ext_if="lo0" # For a 512/128 kbps ADSL with PPPoE link, using "bandwidth 100Kb" # is optimal. Some experimentation might be needed to find the best # value. If it's set too high, the priority queue is not effective, and # if it's set too low, the available bandwidth is not fully used. # A good starting point would be real_uplink_bandwidth * 90 / 100. altq on $ext_if priq bandwidth 100Kb queue { q_pri, q_def } queue q_pri priority 7 queue q_def priority 1 priq(default) pass out on $ext_if proto tcp from $ext_if to any flags S/SA \ keep state queue (q_def, q_pri) pass in on $ext_if proto tcp from any to $ext_if flags S/SA \ keep state queue (q_def, q_pri)