Linux Traffic Control
Using the tc (traffic control) utility in Linux, it is possible to simulate various network conditions, such as latency, packet loss, random conditions, etc.
List existing tc rules:
sudo /usr/sbin/tc -p qdisc ls dev eth0
Delete existing tc rules:
sudo /usr/sbin/tc -p qdisc del dev eth0 root
Add vs. Change
If a rule does not already exist, use the add command option:
sudo /usr/sbin/tc qdisc add dev eth0 root netem delay 10ms
If a rule already exists, use the change command option:
sudo /usr/sbin/tc qdisc change dev eth0 root netem delay 10ms
Simple Delay / Latency
Add 10ms of delay / latency:
sudo /usr/sbin/tc qdisc add dev eth0 root netem delay 10ms
This command simply adds 10ms of delay:
jemurray@shell:~$ ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=57 time=1.57 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=57 time=1.37 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=57 time=1.29 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=57 time=1.29 ms
64 bytes from 8.8.8.8: icmp_seq=5 ttl=57 time=1.25 ms
64 bytes from 8.8.8.8: icmp_seq=6 ttl=57 time=11.4 ms
64 bytes from 8.8.8.8: icmp_seq=7 ttl=57 time=11.4 ms
64 bytes from 8.8.8.8: icmp_seq=8 ttl=57 time=11.4 ms
64 bytes from 8.8.8.8: icmp_seq=9 ttl=57 time=11.3 ms
64 bytes from 8.8.8.8: icmp_seq=10 ttl=57 time=11.5 ms
64 bytes from 8.8.8.8: icmp_seq=11 ttl=57 time=11.4 ms
64 bytes from 8.8.8.8: icmp_seq=12 ttl=57 time=1.31 ms
64 bytes from 8.8.8.8: icmp_seq=13 ttl=57 time=1.43 ms
64 bytes from 8.8.8.8: icmp_seq=14 ttl=57 time=1.35 ms
64 bytes from 8.8.8.8: icmp_seq=15 ttl=57 time=1.32 ms
Random Delay / Latency
sudo /usr/sbin/tc qdisc add dev eth0 root netem delay 20ms 10ms 25%
This command adds 20ms of delay, randomizes by +/- 10ms with a 25% variance:
jemurray@shell:~$ ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=57 time=1.57 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=57 time=1.35 ms
64 bytes from 8.8.8.8: icmp_seq=3 ttl=57 time=1.35 ms
64 bytes from 8.8.8.8: icmp_seq=4 ttl=57 time=1.29 ms
64 bytes from 8.8.8.8: icmp_seq=5 ttl=57 time=1.42 ms
64 bytes from 8.8.8.8: icmp_seq=6 ttl=57 time=11.9 ms
64 bytes from 8.8.8.8: icmp_seq=7 ttl=57 time=17.2 ms
64 bytes from 8.8.8.8: icmp_seq=8 ttl=57 time=19.5 ms
64 bytes from 8.8.8.8: icmp_seq=9 ttl=57 time=27.4 ms
64 bytes from 8.8.8.8: icmp_seq=10 ttl=57 time=28.8 ms
64 bytes from 8.8.8.8: icmp_seq=11 ttl=57 time=30.1 ms
64 bytes from 8.8.8.8: icmp_seq=12 ttl=57 time=20.5 ms
64 bytes from 8.8.8.8: icmp_seq=13 ttl=57 time=19.10 ms
64 bytes from 8.8.8.8: icmp_seq=14 ttl=57 time=12.9 ms
64 bytes from 8.8.8.8: icmp_seq=15 ttl=57 time=14.7 ms
64 bytes from 8.8.8.8: icmp_seq=16 ttl=57 time=20.6 ms
64 bytes from 8.8.8.8: icmp_seq=17 ttl=57 time=16.7 ms
64 bytes from 8.8.8.8: icmp_seq=18 ttl=57 time=16.10 ms
64 bytes from 8.8.8.8: icmp_seq=19 ttl=57 time=22.9 ms
64 bytes from 8.8.8.8: icmp_seq=20 ttl=57 time=26.9 ms
64 bytes from 8.8.8.8: icmp_seq=21 ttl=57 time=25.8 ms
64 bytes from 8.8.8.8: icmp_seq=22 ttl=57 time=17.3 ms
64 bytes from 8.8.8.8: icmp_seq=23 ttl=57 time=22.7 ms
64 bytes from 8.8.8.8: icmp_seq=24 ttl=57 time=20.2 ms
64 bytes from 8.8.8.8: icmp_seq=25 ttl=57 time=29.7 ms
64 bytes from 8.8.8.8: icmp_seq=26 ttl=57 time=30.4 ms
64 bytes from 8.8.8.8: icmp_seq=27 ttl=57 time=13.5 ms
64 bytes from 8.8.8.8: icmp_seq=28 ttl=57 time=29.3 ms
64 bytes from 8.8.8.8: icmp_seq=29 ttl=57 time=26.4 ms
64 bytes from 8.8.8.8: icmp_seq=30 ttl=57 time=12.6 ms
64 bytes from 8.8.8.8: icmp_seq=31 ttl=57 time=1.29 ms
64 bytes from 8.8.8.8: icmp_seq=32 ttl=57 time=1.43 ms
64 bytes from 8.8.8.8: icmp_seq=33 ttl=57 time=1.30 ms
64 bytes from 8.8.8.8: icmp_seq=34 ttl=57 time=1.36 ms
Random packet loss
sudo /usr/sbin/tc qdisc change dev eth0 root netem loss 10% 25%
This command simulates 10% packet loss with a 25% probability of successive loss:
My traceroute [v0.92]
shell (104.131.191.87) 2020-05-04T23:52:38+0000
Keys: Help Display mode Restart statistics Order of fields quit
Packets Pings
Host Loss% Snt Last Avg Best Wrst StDev
1. 104.131.0.254 1.2% 82 0.4 1.4 0.4 20.2 3.0
2. 138.197.248.6 0.0% 82 8.8 1.2 0.5 23.0 2.9
3. 138.197.244.44 1.2% 82 1.0 1.3 0.9 5.7 0.8
4. 162.243.191.243 1.2% 82 3.3 1.4 1.0 8.5 1.1
5. 108.170.248.97 0.0% 82 1.5 1.4 1.3 1.7 0.1
6. 172.253.72.129 0.0% 81 1.5 1.5 1.4 1.8 0.1
7. lga34s15-in-f14.1e100.net 2.5% 81 1.4 1.5 1.4 1.6 0.1
Using tc to manipulate performance testing with iperf3
Baseline test with no tc rules applied:
jemurray@shell:~$ iperf3 -t 10 -i 1 -c 128.252.5.113
Connecting to host 128.252.5.113, port 5201
[ 5] local 104.131.191.87 port 43942 connected to 128.252.5.113 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 62.9 MBytes 527 Mbits/sec 3 5.49 MBytes
[ 5] 1.00-2.00 sec 82.5 MBytes 692 Mbits/sec 0 5.49 MBytes
[ 5] 2.00-3.00 sec 82.5 MBytes 692 Mbits/sec 0 5.49 MBytes
[ 5] 3.00-4.00 sec 81.2 MBytes 682 Mbits/sec 0 5.49 MBytes
[ 5] 4.00-5.00 sec 82.5 MBytes 692 Mbits/sec 0 5.49 MBytes
[ 5] 5.00-6.00 sec 81.2 MBytes 682 Mbits/sec 0 5.49 MBytes
[ 5] 6.00-7.00 sec 82.5 MBytes 692 Mbits/sec 0 5.49 MBytes
[ 5] 7.00-8.00 sec 81.2 MBytes 682 Mbits/sec 0 5.49 MBytes
[ 5] 8.00-9.00 sec 82.5 MBytes 692 Mbits/sec 0 5.49 MBytes
[ 5] 9.00-10.00 sec 82.5 MBytes 692 Mbits/sec 0 5.49 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 802 MBytes 672 Mbits/sec 3 sender
[ 5] 0.00-10.04 sec 801 MBytes 669 Mbits/sec receiver
iperf Done.
sudo /usr/sbin/tc qdisc add dev eth0 root netem loss 10% 25%
Applying 10% packet loss:
jemurray@shell:~$ iperf3 -t 10 -i 1 -c 128.252.5.113
Connecting to host 128.252.5.113, port 5201
[ 5] local 104.131.191.87 port 43946 connected to 128.252.5.113 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 1.28 MBytes 10.7 Mbits/sec 4 22.6 KBytes
[ 5] 1.00-2.00 sec 764 KBytes 6.26 Mbits/sec 5 22.6 KBytes
[ 5] 2.00-3.00 sec 764 KBytes 6.26 Mbits/sec 6 22.6 KBytes
[ 5] 3.00-4.00 sec 382 KBytes 3.13 Mbits/sec 8 11.3 KBytes
[ 5] 4.00-5.00 sec 382 KBytes 3.13 Mbits/sec 4 17.0 KBytes
[ 5] 5.00-6.00 sec 382 KBytes 3.13 Mbits/sec 10 14.1 KBytes
[ 5] 6.00-7.00 sec 382 KBytes 3.13 Mbits/sec 4 21.2 KBytes
[ 5] 7.00-8.00 sec 764 KBytes 6.26 Mbits/sec 6 12.7 KBytes
[ 5] 8.00-9.00 sec 382 KBytes 3.13 Mbits/sec 4 25.5 KBytes
[ 5] 9.00-10.00 sec 382 KBytes 3.13 Mbits/sec 9 12.7 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 5.76 MBytes 4.83 Mbits/sec 60 sender
[ 5] 0.00-10.04 sec 5.08 MBytes 4.25 Mbits/sec receiver
iperf Done.
sudo /usr/sbin/tc qdisc change dev eth0 root netem delay 100ms 10ms 25%
Adding 100ms of latency:
jemurray@shell:~$ iperf3 -t 10 -i 1 -c 128.252.5.113
Connecting to host 128.252.5.113, port 5201
[ 5] local 104.131.191.87 port 43950 connected to 128.252.5.113 port 5201
[ ID] Interval Transfer Bitrate Retr Cwnd
[ 5] 0.00-1.00 sec 4.09 MBytes 34.3 Mbits/sec 4 543 KBytes
[ 5] 1.00-2.00 sec 18.8 MBytes 157 Mbits/sec 0 4.35 MBytes
[ 5] 2.00-3.00 sec 26.2 MBytes 220 Mbits/sec 0 4.35 MBytes
[ 5] 3.00-4.00 sec 22.5 MBytes 189 Mbits/sec 0 4.35 MBytes
[ 5] 4.00-5.00 sec 22.5 MBytes 189 Mbits/sec 0 4.35 MBytes
[ 5] 5.00-6.00 sec 26.2 MBytes 220 Mbits/sec 0 4.35 MBytes
[ 5] 6.00-7.00 sec 23.8 MBytes 199 Mbits/sec 0 4.35 MBytes
[ 5] 7.00-8.00 sec 25.0 MBytes 210 Mbits/sec 0 4.35 MBytes
[ 5] 8.00-9.00 sec 26.2 MBytes 220 Mbits/sec 0 4.35 MBytes
[ 5] 9.00-10.00 sec 26.2 MBytes 220 Mbits/sec 0 4.35 MBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bitrate Retr
[ 5] 0.00-10.00 sec 222 MBytes 186 Mbits/sec 4 sender
[ 5] 0.00-10.13 sec 219 MBytes 182 Mbits/sec receiver
iperf Done.