Echo error detection

The echo method puts a lot of extra traffic onto the network, but it is conceptually a very simple idea. First of all the packet is sent from the source PC to the destination PC. The destination PC will then send the packet straight back. The destination PC will then compare this packet with the one it originally sent. If they are the same then nothing happens. If there is a difference then an error must have occurred. In this case the message is resent.

There are two major problems with this technique. The first is that it dramatically increases network traffic. This means that each packet must be sent at least twice. The second problem is if the error is introduced to the packet as it returns to the source. In this case the destination PC did receive the packet correctly only its response has become corrupted. In this case the message must be resent.