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I'm looking for an app that I can run to test available bandwidth (and error rate) over a LAN. I'm thinking of a pair of programs that run on two computers and send a big known block of data from one computer to another and checks it on the receiving end.

If I were on Linux, I could get somthing working with time, cat, nc and md5 or diff but I'm on Windows.

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There are plenty of network load generators out there. However the error rate should be 0 as tcp will detect any problems and retransmit packets that fail to arrive or arrive with bad checksums. You should be able to find out how many send/receive errors and dropped packets occurred from the hosts involved by looking at the statistics from their NIC. However a managed switch should be able to show you the global picture of these sort of things.

Here's a load generator made for networks:

This is also a nice testing app but its main use is to test a file server. But it will do the job of testing the network connections as well. It can simulate multiple clients and access patterns as well.

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Oh.. I forgot TCP and UDP had checksums. – BCS Sep 30 '09 at 21:50
What exactly are you trying to test? The network is only there to get bits from point a to point b once the bits arrive at their destination it's up to the file system and OS to make sure that the bits make their way to the disk safely. UDP is just a best effort protocol and shouldn't be used where every bit needs to make it across the network. So if your test fails to successfully send a file from client a to client b over UDP all you are going to prove is that UDP isn't a good protocol for the task at hand. – 3dinfluence Sep 30 '09 at 21:52
I want some way to check if some newly installed wires are good. More than just are the right wires connected to the right pins but does it actually pass data with a reasonable error rate. – BCS Oct 1 '09 at 17:21
They make hardware for that. The ones that test the noise and interference on the lines are not cheap. Something like these Otherwise you can detect network issues with a managed switch. They will tell you the link speed negotiated on the port and detailed information about send/receive errors, packet size, fragmentation, etc. – 3dinfluence Oct 1 '09 at 17:59

I've always used NetCPS. If it doesn't immediately meet your needs, it's open-source, so you might be able to extend it.

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That looks like it might work. – BCS Sep 30 '09 at 17:00

IxChariot will transfer a block of your own definition between agents residing on any two hosts of your choice, up to and including the ability to embed agents in custom hardware for WiFi certification testing.

I don't work for the vendor. I don't work for a VAR for the vendor. I have received no compoensation from the endorsement of this exceptionally cool network test tool.

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