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@mikkorantalainen
Created April 4, 2019 18:20
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#!/bin/bash
# Traffic shaping script (AQM, fq_codel+tbf)
# Copyright 2018 Mikko Rantalainen <mikko.rantalainen@gmail.com>
# License: MIT (X11)
# Usage:
# 21/0.8 Mbps connection (ADSL2): DOWNLINK_RATE=21.7Mbit UPLINK_RATE=0.8Mbit TBF_LATENCY=500ms bin/traffic-shaping start
# 100/100 Mbps connection: ./traffic-shaping
# 1/1 GBps connection: DOWNLINK_RATE=1Gbit UPLINK_RATE=1Gbit TBF_LATENCY=10ms bin/traffic-shaping start
# Note that using low TBF_LATENCY will require powerful CPU.
#
# See also: https://www.bufferbloat.net/projects/codel/wiki/Best_practices_for_benchmarking_Codel_and_FQ_Codel/
# See also: http://www.jfcarter.net/~jimc/documents/voip-qos-1609.html
# TODO: man 7 tc-hfcs (instead of tbf)
# TODO: try to limit bandwidth using fq_codel only (get rid of tbf) - https://gist.github.com/eqhmcow/939373/8d2e8ad745a7e0a8ddb21abde42538034c2ea65b
#
set -e # abort if a command returns non-zero status (failed)
#set -x # verbose execution
DEV="${DEV:=$(ip route | grep "^default " | grep -Po "(?<=dev )[^ ]+" | uniq)}"
# ingress:
DOWNLINK_RATE="${DOWNLINK_RATE:=106000kbit}" # or e.g. "21.5Mbit"
# egress:
UPLINK_RATE="${UPLINK_RATE:=101000kbit}"
CODEL_INTERVAL="${CODEL_INTERVAL:=100ms}" # usually 100ms, high speed links with low latency may need lower values
CODEL_TARGET="${CODEL_TARGET:=5ms}" # unit "us" is also available, usually 5%-10% of CODEL_INTERVAL
CODEL_LIMIT="${CODEL_LIMIT:=1001}" # decrease to reduce latency, too low values will limit throughput
CODEL_FLOWS="${CODEL_FLOWS:=1024}"
# set burst as high as possible without causing dropped packets at the start of the connections
DOWNLINK_BURST="${DOWNLINK_BURST:=6500}"
UPLINK_BURST="${UPLINK_BURST:=6500}"
TBF_LATENCY="${TBF_LATENCY:=14ms}" # set to lower latency to improve control over bandwidth limiting, UPLINK_BURST bytes must be able to be sent in this time
IFB="$DEV.ingress"
INITCWND="${INITCWND:=15}" # initial congestion window, decrease if packet loss is seen
INITRWND="${INITRWND:=40}" # initial receiving window (advertised from client to servers), can be safely pretty high if you have lots of bandwidth (Windows and OS X have this near 40)
# See also: https://www.cdnplanet.com/blog/tune-tcp-initcwnd-for-optimum-performance/
# See also: https://www.acc.umu.se/~maswan/linux-netperf.txt
# See also: http://intronetworks.cs.luc.edu/1/html/newtcps.html
# See also: https://www.ietf.org/proceedings/84/slides/slides-84-iccrg-1.pdf
configure_shaping()
{
# EGRESS (outgoing traffic, "uploads"):
# setup bandwidth limiting:
tc qdisc add dev "$DEV" root handle 1: tbf rate "$UPLINK_RATE" burst "$UPLINK_BURST" latency "$TBF_LATENCY"
# setup fq_codel for bandwidth shaping
tc qdisc add dev "$DEV" parent 1: fq_codel quantum 300 limit "$CODEL_LIMIT" target "$CODEL_TARGET" interval "$CODEL_INTERVAL" flows "$CODEL_FLOWS" noecn
# INGRESS (incoming traffic, "downloads"):
# setup bandwidth limiting (ingress limiting needs IFB or Intermediate Functional Block, see https://wiki.linuxfoundation.org/networking/ifb):
tc qdisc add dev "$DEV" handle ffff: ingress
ip link add name "$IFB" type ifb
tc qdisc add dev "$IFB" root handle 1: tbf rate "$DOWNLINK_RATE" burst "$DOWNLINK_BURST" latency "$TBF_LATENCY"
# setup fq_codel for bandwidth shaping
tc qdisc add dev "$IFB" parent 1: fq_codel quantum 300 limit "$CODEL_LIMIT" target "$CODEL_TARGET" interval "$CODEL_INTERVAL" flows "$CODEL_FLOWS" ecn
ip link set dev "$IFB" up
# connect ingress filtering to actual WAN device
tc filter add dev "$DEV" parent ffff: protocol all prio 10 u32 match u32 0 0 flowid 1:1 action mirred egress redirect dev "$IFB"
# configure initcwnd and initrwnd
ip route change $(ip route | grep ^default) initcwnd "$INITCWND" initrwnd "$INITRWND"
## configure CDG congestion control algorithm
##modprobe tcp_cdg && echo cdg > /proc/sys/net/ipv4/tcp_congestion_control
# cubic seems to be better overall with AQM, let's tune it
echo cubic > /proc/sys/net/ipv4/tcp_congestion_control || true
echo 13 > /sys/module/tcp_cubic/parameters/hystart_low_window
echo 0 > /proc/sys/net/ipv4/tcp_slow_start_after_idle
# TODO: try modprobe tcp_westwood
}
remove_shaping()
{
#set -x
tc qdisc list | grep -q "ingress" && tc qdisc del dev "$DEV" ingress || true
# Note: we need to avoid removing root qdisc in case this kernel defaults to fq_codel, "qdisc list" will output "fq_codel 0:" for root qdisc so we look for something different
tc qdisc list | grep -q "fq_codel [1-9]" && tc qdisc del dev "$DEV" root || true
ip link show | grep -q "$IFB" && ip link del "$IFB" || true
# configure CDG congestion control algorithm
modprobe tcp_cdg && echo cdg > /proc/sys/net/ipv4/tcp_congestion_control || true
#set +x
}
status()
{
echo "─── queue discipline configuration: ──────────────────"
tc qdisc list
echo " TIP: use e.g. 'sudo tc qdisc del dev $DEV ingress' to remove ingress filtering"
echo " TIP: use e.g. 'sudo tc qdisc del dev $DEV root' to remove egress filtering"
echo "─── ip link show: ────────────────────────────────────"
ip link show
echo " TIP: use e.g. 'sudo ip link del $IFB' to remove ingress device"
}
color_status()
{
status | grep --color=auto -E "^|$DEV|$IFB|rate [^ ]+"
}
# handle parameters
ACTION="$1"
shift || true
while [ ! -z "$1" ]
do
case "$1" in
-v|--verbose)
echo "Device: $DEV"
echo "Downlink rate (ingress): $DOWNLINK_RATE"
echo "Uplink rate (egress): $UPLINK_RATE"
set -x
;;
*)
if [ ! -z "$2" ]; then
echo "Unknown parameter: '$2'" 1>&2
exit 1
fi
;;
esac
shift || true
done
case "$ACTION" in
start)
remove_shaping
configure_shaping
;;
stop)
remove_shaping
;;
status)
color_status
;;
restart)
remove_shaping
configure_shaping
;;
*)
echo "Unknown action: $1" 1>&2
echo "Usage: $0 <start|stop|restart|status> [--verbose|-v]" 1>&2
exit 1
esac
@mikkorantalainen
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See also: https://youtu.be/quAaZKBHvs8
See also: man tc-sfq

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