Delay and loss tests using netem on a healthy network

Purpose of this document

We needed a lab environment that can provide a "break on purpose network" to developers to test their code on it. You can add;

• delay
• packet loss
• jitter
• duplicate packets
• unordered flows

to a connection on the fly. To do it we need "netem" modules help.

NETEM

Since kernel 2.6 netem is included in iproute2 package, basically all modern distro's has it now. You can find a documentation on Netem

i am going to explain the required steps here ;

• create a master traffic class on interface ens8

    sudo tc qdisc add dev ens8 root handle 1: prio
  

• Attach a subclass to tc 1: as 3

    sudo tc qdisc add dev ens8 parent 1:3 handle 30: netem delay 1000ms
    sudo tc filter add dev ens8 protocol ip parent 1:0 prio 3 u32 match ip dst 51.195.19.172 flowid 1:3