32 lines
1.2 KiB
Plaintext
32 lines
1.2 KiB
Plaintext
# $FreeBSD$
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# $OpenBSD: ackpri,v 1.3 2006/10/07 04:48:01 mcbride Exp $
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# Use a simple priority queue to prioritize empty (no payload) TCP ACKs,
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# which dramatically improves throughput on (asymmetric) links when the
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# reverse direction is saturated. The empty ACKs use an insignificant
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# part of the bandwidth, but if they get delayed, downloads suffer
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# badly, so prioritize them.
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# Example: 512/128 kbps ADSL. Download is 50 kB/s. When a concurrent
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# upload saturates the uplink, download drops to 7 kB/s. With the
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# priority queue below, download drops only to 48 kB/s.
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# Replace lo0 with your real external interface
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ext_if="lo0"
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# For a 512/128 kbps ADSL with PPPoE link, using "bandwidth 100Kb"
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# is optimal. Some experimentation might be needed to find the best
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# value. If it's set too high, the priority queue is not effective, and
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# if it's set too low, the available bandwidth is not fully used.
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# A good starting point would be real_uplink_bandwidth * 90 / 100.
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altq on $ext_if priq bandwidth 100Kb queue { q_pri, q_def }
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queue q_pri priority 7
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queue q_def priority 1 priq(default)
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pass out on $ext_if proto tcp from $ext_if to any queue (q_def, q_pri)
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pass in on $ext_if proto tcp from any to $ext_if queue (q_def, q_pri)
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