Dummynet - Burst Loss

[Harkirat Singh]

Hello!

I want to know is it possible to create a burst of packet loss
using dummynet. I have used Dummynet to create a random packet
loss and quiet familiar with it. However, I did not get any information as
how a burst of packet loss can be created.

I shall be greatfull if someone can guide me about this..

Regards,

harkirat Singh

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[Patrick O'Reilly]

Posting back to Questions only:

The only thought that occurs to me would be to write a two line script to
change the config of the pipe to increase the loss percentage to 80% or 100%
(whatever suits you), then return to 0% or 5% after whatever delay you are
after. This could be triggered manually or even in cron if that's what you
need.

try something like this:
----------
#!/bin/sh
# Assuming your pipe number 99 matches the packet
# stream which you want test with the 'burst loss'
ipfw pipe 99 config plr $2
sleep $1
ipfw pipe 99 config plr 0
----------

If this script is called 'loss-burst' in your current directory, you could
invoke it like such:

# ./loss-burst 3 0.95

This would give you a 95% packet loss rate for 3 seconds. I guess you could
easily add an argument to specify the ipfw pipe number too.

Hope this helps.

Patrick.

[Harkirat Singh]

I appreciate your detailed reply!!

In Dummynet "bandwidth" and "queue" is used, is there a way to use queue
and bandwidth combination for burst packet loss?

Regards,

harkirat