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Traffic generators: overview

	tcpblast	ttcp	iperf	AB	Linbot & wget	ping
TCP	YES	YES	YES	YES	YES	NO
UDP	YES	YES	YES	YES	NO	NO
ICMP	NO	NO	NO	NO	NO	YES
client-server (1)	NO	YES	YES	NO	NO	NO
Multiple streams	NO	YES	YES	YES	YES	NO
Full BandWidth? (2)	YES	YES	NO (UDP:YES)	NO	NO	NO
MTU (3)	NO	NO	YES	NO	NO	NO

(1): ttcp and iperf are server/client programs. So you have to start on 1 PC the server and an other PC can act as client and connects to the server and send the data.

(2): tcpblast, ttcp and iperf (TCP) are sending as much data they can. When iperf sends UDP you can specify a rate. AB and Linbot are querying a web-server so they generate as much as the webserver can deliver and as much the scripts can proces. You can start several pings in the background to generate the rate you want or you can specify the -f parameter to flood the destination host.

(3): With iperf you can specify the TCP maximum segment wich is MTU - 40bytes. You can also specify the TCP window size.

tcpblast

local copy: I found this little program in the contrib area of MRTG (Multi Router Traffic Grapher).

# ./tcpblast --help
 
 usage: ./tcpblast [options] destination nblocks
  
  tcpblast/udpblast is a simple tool for probing network and estimating its
  through output. It sends nblocks of 1024 B blocks of data to specified
  destination host

I'm using this program to generate the traffic and not to measure the bandwidth. But tcpblast is only a client program. It can kill the destination server because it's overloading the server by sending random traffic on a port.

ttcp

local copy: This is a server-client program that generates traffic between them. It works great and I choose it above tcpblast. With ttcp you don't risk to overload the destination server.

Starting the server on poort POORT1:

while true; do ttcp -r -s -p $POORT1; done

Connecting with a client to server SERVER:

while true ;do ttcp -t -s $SERVER -p $POORT1; done

client-server setup: you can split on destination port
Only one parallel connection, so one big data stream
Allways tries to generate as much traffic as possibility

iperf

local copy (Home page): This is also a client-server program that measured the bandwidth. It has more options than ttcp. It can also generates parallel connections.

client-server setup: you can split on destintaion port
Possibility to generate parallel connections to the same destination port in one big data stream
Allways tries to generate as much traffic as possibility. When you use UDP, you can specify a limit to the transmitted traffic.

Apache Benchmark & linbot & wget

Apache Benchmark

Tool to test web-server so lot of small connections to one destination port
Possibility to generate parallel connections to the same destination port
Generates about 20KByte/s to my test server (Linux, P120Mhz, 32MB Ram)

As results, a lot of small connectionts are generated. This is the results of the netstat command when I generated 8 parallel connections.

$ netstat | grep kriek:www
tcp        0      1 192.168.1.128:4279      kriek:www               SYN_SENT
tcp        0      1 192.168.1.128:4278      kriek:www               LAST_ACK
tcp        0      0 192.168.1.128:4277      kriek:www               CLOSE
tcp        0      0 192.168.1.128:4276      kriek:www               CLOSE
tcp        0      0 192.168.1.128:4275      kriek:www               CLOSE
tcp        0      0 192.168.1.128:4274      kriek:www               CLOSE
tcp        0      0 192.168.1.128:4273      kriek:www               CLOSE

Linbot & wget

Linbot is a tool to test the html pages of web-servers. It queries all the pages of the web-servers and looks for broken links. So it generates a lot of small connections to download different files. I think this is the best tool you can get to generate real traffic.

An other tool that can be used is wget. This downloads all the files from a web-server.

ping

Starting ping with the option -f, floods the destination hosts and creates a lot of bandwitdh.