186d7f5d3SJohn Marino# $OpenBSD: ackpri,v 1.2 2003/03/10 14:24:33 henning Exp $ 286d7f5d3SJohn Marino# $DragonFly: src/share/examples/pf/ackpri,v 1.1 2005/12/13 01:58:27 corecode Exp $ 386d7f5d3SJohn Marino 486d7f5d3SJohn Marino# Use a simple priority queue to prioritize empty (no payload) TCP ACKs, 586d7f5d3SJohn Marino# which dramatically improves throughput on (asymmetric) links when the 686d7f5d3SJohn Marino# reverse direction is saturated. The empty ACKs use an insignificant 786d7f5d3SJohn Marino# part of the bandwidth, but if they get delayed, downloads suffer 886d7f5d3SJohn Marino# badly, so prioritize them. 986d7f5d3SJohn Marino 1086d7f5d3SJohn Marino# Example: 512/128 kbps ADSL. Download is 50 kB/s. When a concurrent 1186d7f5d3SJohn Marino# upload saturates the uplink, download drops to 7 kB/s. With the 1286d7f5d3SJohn Marino# priority queue below, download drops only to 48 kB/s. 1386d7f5d3SJohn Marino 1486d7f5d3SJohn Marino# Replace lo0 with your real external interface 1586d7f5d3SJohn Marino 1686d7f5d3SJohn Marinoext_if="lo0" 1786d7f5d3SJohn Marino 1886d7f5d3SJohn Marino# For a 512/128 kbps ADSL with PPPoE link, using "bandwidth 100Kb" 1986d7f5d3SJohn Marino# is optimal. Some experimentation might be needed to find the best 2086d7f5d3SJohn Marino# value. If it's set too high, the priority queue is not effective, and 2186d7f5d3SJohn Marino# if it's set too low, the available bandwidth is not fully used. 2286d7f5d3SJohn Marino# A good starting point would be real_uplink_bandwidth * 90 / 100. 2386d7f5d3SJohn Marino 2486d7f5d3SJohn Marinoaltq on $ext_if priq bandwidth 100Kb queue { q_pri, q_def } 2586d7f5d3SJohn Marinoqueue q_pri priority 7 2686d7f5d3SJohn Marinoqueue q_def priority 1 priq(default) 2786d7f5d3SJohn Marino 2886d7f5d3SJohn Marinopass out on $ext_if proto tcp from $ext_if to any flags S/SA \ 2986d7f5d3SJohn Marino keep state queue (q_def, q_pri) 3086d7f5d3SJohn Marino 3186d7f5d3SJohn Marinopass in on $ext_if proto tcp from any to $ext_if flags S/SA \ 3286d7f5d3SJohn Marino keep state queue (q_def, q_pri) 3386d7f5d3SJohn Marino 34