Network Simulation

• Linux Network emulator linuxfoundation

• Delay all packets out eth0

  •    # tc qdisc add dev eth0 root netem delay 100ms

• Delay + 10ms variation, each 25% correlated to previous value.

  •    # tc qdisc change dev eth0 root netem delay 100ms 10ms 25%

• Other options
  • loss 0.3% 25% (% loss and correlation)
  • duplicate 1%

  • corrupt 0.1% << corrupts single bit

Rate control

• There is no rate control built-in to the netem discipline, use Token Bucket Filter (TBF) to limit output.

   # tc qdisc add dev eth0 root handle 1:0 netem delay 100ms
   # tc qdisc add dev eth0 parent 1:1 handle 10: tbf rate 256kbit buffer 1600 limit 3000
   # tc -s qdisc ls dev eth0
   qdisc netem 1: limit 1000 delay 100.0ms
     Sent 0 bytes 0 pkts (dropped 0, overlimits 0 )
   qdisc tbf 10: rate 256Kbit burst 1599b lat 26.6ms
     Sent 0 bytes 0 pkts (dropped 0, overlimits 0 )

• To check status

   tc -s qdisc

• To remove the delay from eth0

   tc qdisc del dev eth0 root