Netem

Contents

The following scenario shows how to configure a Network Emulator qdisc.

Test NetEm QDisc

Description

In this scenario, a Network Emulator (NetEm) qdisc is configured in DUT0 to add certain characteristics (like delay or packet loss) to packets leaving the ‘eth0’ interface.

Scenario

Step 1: Set the following configuration in DUT0:

set interfaces ethernet eth0 address 10.0.0.2/24
set interfaces ethernet eth0 traffic control out QDISC
set traffic control QDISC type network-emulator packet-corruption 0.05
set traffic control QDISC type network-emulator network-delay 0.05
set traffic control QDISC type network-emulator packet-loss 0.05

Step 2: Set the following configuration in DUT1:

set interfaces ethernet eth0 address 10.0.0.1/24

Step 3: Ping IP address 10.0.0.1 from DUT0:

admin@DUT0$ ping 10.0.0.1 count 1 size 56 timeout 1

Show output

PING 10.0.0.1 (10.0.0.1) 56(84) bytes of data.
64 bytes from 10.0.0.1: icmp_seq=1 ttl=64 time=0.517 ms

--- 10.0.0.1 ping statistics ---
1 packets transmitted, 1 received, 0% packet loss, time 0ms
rtt min/avg/max/mdev = 0.517/0.517/0.517/0.000 ms

Step 4: Initiate a bandwidth test from DUT0 to DUT1

admin@DUT1$ monitor test performance server port 8080
admin@DUT0$ monitor test performance client 10.0.0.1 duration 5 port 8080

Expect this output in DUT0:

Connecting to host 10.0.0.1, port 8080
[  5] local 10.0.0.2 port 34456 connected to 10.0.0.1 port 8080
[ ID] Interval           Transfer     Bitrate         Retr  Cwnd
[  5]   0.00-1.00   sec  53.5 MBytes   448 Mbits/sec   45   2.15 MBytes
[  5]   1.00-2.19   sec  12.5 MBytes  88.1 Mbits/sec  250   1.79 MBytes
[  5]   2.19-3.09   sec  17.5 MBytes   164 Mbits/sec    1   1.36 MBytes
[  5]   3.09-4.07   sec  65.0 MBytes   555 Mbits/sec   48    382 KBytes
[  5]   4.07-5.01   sec  91.2 MBytes   818 Mbits/sec    0    539 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bitrate         Retr
[  5]   0.00-5.01   sec   240 MBytes   402 Mbits/sec  344             sender
[  5]   0.00-5.01   sec   237 MBytes   398 Mbits/sec                  receiver

iperf Done.

Step 5: Run command traffic control show at DUT0 and check if output contains the following tokens:

netem

Show output

Traffic control for interface 'eth0' - 'egress' mode

------------------------------------------------------------------------
ID   traffic control  type   parent  bytes sent  pkts sent  pkts dropped
------------------------------------------------------------------------
1:0  QDISC            netem  root     261256513     172612             2

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