Traffic simulation tools

[KOM]

Does anyone have any suggestions for tools to simulate or generate network traffic for use with Traffic-shaping testing?  Something that lets you specify duration, bandwidth & ports, and then it spew out random packets of the specified port(s) at the specified bandwidth rate.  Nothing that requires reading a tome to figure out.

[Nullity]

There are quite a few out there for local testing, like netperf or iperf.

Here is a quote from Kenjiro Cho, ALTQ creator ; http://www.iijlab.net/~kjc/software/TIPS.txt

1.4 Traffic Generation
    Even when you have a bottleneck, it is not a simple task to control
    the queue length.
    I recommend to use TCP; a UDP stream just overflows the queue and
    eats up the CPU power and the link bandwidth.
    But a single TCP will not grow the queue length; TCP is clever
    enough!

    You have to run multiple TCP streams to observe some interesting
    traffic dynamics.

    The following simple script works for me.

		#!/bin/sh
		PATH=/bin:/usr/bin:/usr/local/bin
		export PATH

		dest=dest-host-name
		sec=20
		win=48K
		size=8K
		netperf -H $dest -l $sec – -m $size -s $win -S $win &
		sleep 3
		netperf -H $dest -l $sec -- -m $size -s $win -S $win &
		sleep 3
		netperf -H $dest -l $sec -- -m $size -s $win -S $win &
		sleep 3
		netperf -H $dest -l $sec -- -m $size -s $win -S $win

For the testing the dynamics of larger networks, there are things like ns2 and ns3 but they are too complex for anyone but academians.

IMUNES is pretty good, but I did not know enough about FreeBSD virtualization to enable ALTQ, so I gave up, for now.

There are some Linux-based simulators out there but iptables can go to hell, all day, every day, imo.

This site has some good reviews.
http://www.brianlinkletter.com/open-source-network-simulators/

If you find anything interesting, please share! :)

[KOM]

Yeah, I also spent time looking at traffic generators and network simulators.  I didn't find anything that hit the sweet spot.  I don't have the time to learn some massive framework so I was hoping for something not too complex.  Thanks for replying.

[Nullity]

My next venture is to learn more about debugging ALTQ so I can see more stats. I am assuming I will need to resort to a full FreeBSD to get more control of the system though. Learning more about FreeBSD is probably a good idea.

I bet that the bufferbloat/Codel mailing-list has some great info about how to simulate traffic for testing.

I have only played with netperf casually. The few worthwhile tests I ran I did with either multiple sessions of iperf, or multiple sessions of netcat/nc. Netcat is insanely powerful. Every few months since I learned of netcat I am amazed by how powerful the simple tool can be; "netcat host2 port < /dev/zero" to a listening netcat and bam, single stream TCP/UDP traffic. or send a file with the same method. or create a remote shell. That is just the standard uses.

There is gns3, but it is Cisco emulation primarily. Good userbase and polished interface.

There must be a good, simple simulator, right? Call DARPA maybe? ;)