4.1. Set traffic control (tcset command)

tcset is a command to add traffic control rule to a network interface (device).

You can delete rule(s) from a network interface by Delete traffic control (tcdel command).

4.1.1. tcset command help

usage: tcset [-h] [–version] [–tc-command | –tc-script] [–debug | –quiet]
(–device DEVICE | -f CONFIG_FILE) [–overwrite | –change | –add] [–direction {outgoing,incoming}] [–rate BANDWIDTH_RATE] [–delay NETWORK_LATENCY] [–delay-distro LATENCY_DISTRO_MS] [–loss PACKET_LOSS_RATE] [–duplicate PACKET_DUPLICATE_RATE] [–corrupt CORRUPTION_RATE] [–reordering REORDERING_RATE] [–network DST_NETWORK] [–port DST_PORT] [–src-port SRC_PORT] [–ipv6] [–shaping-algo {tbf,htb}] [–iptables] [–src-network SRC_NETWORK]
optional arguments:
-h, --help show this help message and exit
--version show program’s version number and exit
--tc-command display tc commands to be executed and exit. these commands are not executed.
--tc-script generate a script file that described tc commands which equivalent with execution tcconfig command. the script can be execute without tcconfig package installation.
--debug for debug print.
--quiet suppress execution log messages.
--device DEVICE
 network device name (e.g. eth0)
-f CONFIG_FILE, --config-file CONFIG_FILE
 setting traffic controls from a configuration file. output file of the tcshow.
--overwrite overwrite existing traffic shaping rules.
--change change existing traffic shaping rules to the new one. this option reduces the shaping rule switching side effect (such as traffic spike) compared to –overwrite option. note: the tcset command fail when there are no existing shaping rules.
--add add a traffic shaping rule in addition to existing rules.
Traffic Control:
–direction {outgoing,incoming}
the direction of network communication that impose traffic control. incoming requires Linux kernel version 2.6.20 or later. (default = outgoing)
--rate BANDWIDTH_RATE, --bandwidth-rate BANDWIDTH_RATE
 network bandwidth rate [bit per second]. valid units are either: K/M/G/Kbps/Mbps/Gbps e.g. –rate 10Mbps
 round trip network delay [ms]. the valid range is 0 to 3600000. (default=0)
--delay-distro LATENCY_DISTRO_MS
 distribution of network latency becomes X +- Y [ms] (normal distribution). Here X is the value of –delay option and Y is the value of –delay-dist option). network latency distribution is uniform, without this option.
 round trip packet loss rate [%]. the valid range is 0 to 100. (default=0)
 round trip packet duplicate rate [%]. the valid range is 0 to 100. (default=0)
 packet corruption rate [%]. the valid range is 0 to 100. packet corruption means single bit error at a random offset in the packet. (default=0)
--reordering REORDERING_RATE
 packet reordering rate [%]. the valid range is 0 to 100. (default=0)
--network DST_NETWORK, --dst-network DST_NETWORK
 target IP address/network to control traffic
--port DST_PORT, --dst-port DST_PORT
 target destination port number to control traffic.
--src-port SRC_PORT
 target source port number to control traffic.
--ipv6 apply traffic control to IPv6 packets rather than IPv4.
–shaping-algo {tbf,htb}
shaping algorithm. defaults to htb (recommended).
--iptables use iptables to traffic shaping.
--src-network SRC_NETWORK
 set traffic shaping rule to specific packets that routed from –src-network to –dst-network. this option required to execute with the –iptables option. the shaping rule only affect to outgoing packets (no effect to if you execute with “–direction incoming” option)

Issue tracker: https://github.com/thombashi/tcconfig/issues

4.1.2. Basic usage

Examples of outgoing packet traffic control settings are as follows. e.g. Set a limit on bandwidth up to 100Kbps

# tcset --device eth0 --rate 100k e.g. Set 100ms network latency

# tcset --device eth0 --delay 100 e.g. Set 0.1% packet loss

# tcset --device eth0 --loss 0.1 e.g. All of the above at once

# tcset --device eth0 --rate 100k --delay 100 --loss 0.1 e.g. Specify the IP address of traffic control

# tcset --device eth0 --delay 100 --network e.g. Specify the IP network and port of traffic control

# tcset --device eth0 --delay 100 --network --port 80

4.1.3. Advanced usage Traffic control of incoming packets

Execute tcset command with --direction incoming option to set incoming traffic control. Other options are the same as in the case of the basic usage. e.g. Set traffic control both incoming and outgoing network

# tcset --device eth0 --direction outgoing --rate 200K --network
# tcset --device eth0 --direction incoming --rate 1M --network Requirements

Incoming packet traffic control requires additional ifb module, Which need to the following conditions:

  • Equal or later than Linux kernel version 2.6.20
  • Equal or later than iproute2 package version 20070313 Set latency distribution

Latency setting by --delay option is a uniform distribution. If you are using --delay-distro option, latency decided by a normal distribution. e.g. Set 100ms +- 20ms network latency with normal distribution

# tcset --device eth0 --delay 100 --delay-distro 20 Multiple traffic shaping rules per interface

You can set multiple shaping rules to a network interface with --add option.

tcset --device eth0 --rate 500M --network
tcset --device eth0 --rate 100M --network --add Using IPv6

IPv6 addresses can be used at tcset/tcshow commands with --ipv6 option.

# tcset --device eth0 --delay 100 --network 2001:db00::0/24 --ipv6
# tcshow --device eth0 --ipv6
    "eth0": {
        "outgoing": {
            "dst-network=2001:db00::/24, protocol=ipv6": {
                "delay": "100.0",
                "rate": "1G"
        "incoming": {}
} Get tc commands

You can get tc commands to be executed by tcconfig commands by executing with --tc-command option (no tc configuration have made to the execution server by this command).

# tcset --device eth0 --delay 10 --tc-command
tc qdisc add dev eth0 root handle 1f87: htb default 1
tc class add dev eth0 parent 1f87: classid 1f87:1 htb rate 1000000kbit
tc class add dev eth0 parent 1f87: classid 1f87:2 htb rate 1000000Kbit ceil 1000000Kbit
tc qdisc add dev eth0 parent 1f87:2 handle 2007: netem delay 10.0ms
tc filter add dev eth0 protocol ip parent 1f87: prio 1 u32 match ip dst flowid 1f87:2 Generate a tc script file

--tc-script option generates an executable script which includes tc commands to be executed by tcconfig commands. The created script can execute at other servers where tcconfig not installed (however, you need the tc command to run the script).

# tcset --device eth0 --delay 10 --tc-script
[INFO] tcconfig: written a tc script to 'tcset_eth0.sh'
# ./tcset_eth0.sh