Simulate high speed network connection

Question

I have created a bandwidth meter application to measure total Internet traffic. I need to test the application with relatively high data transfer rates, such as 4 Mbps. I have a slow Internet connection, so I need a simulator to test my application to see the behavior with high throughput rates.

Answer 1

As an option, you can run some HTTP server in one virtual machine with NAT'ed network adapter and test your bandwidth meter against it from the host system or a similar VM.

Answer 2

There are commercial packet generators that do this, and also a few freely available ones like PackETH and Bit-Twist.

There are also other creative solutions. For example, do the packets need to be IP packets for your purpose? If not, you could always get a "dumb" switch or hub (no spanning-tree or other loop protection) and plug a crossover cable into it. (or a straight-through Ethernet cable would work if the switch supports Auto-MDIX) The idea would be that with a loop in your network, the hub/switch will flood the network to 100% for you since it will continually re-forward the same packets.

If you try this, be sure yours is the only computer on the network, since this technique will effectively render it useless. ;-)

You could always send some IP broadcast packets to "seed" the loop. Otherwise, the first thing I think you'd likely see is broadcast ARP packets, which won't help if you're measuring layer 3 traffic only.

Lastly, (and especially if this sounds like too much trouble) I recommend you read up on dependency injection and refactor your code so you can test it without the need for a high-speed interface. Of course, you'll still need to test your code in a real high-speed environment, but doing this will give you much more confidence in your code.