UDP, TCP and VPN

UDP

User Datagram Protocol can be considered a ‘fast and furious’ protocol since it features no error correction once the data packets are sent. This makes UDP very fast – since it’s only receiving and delivering packets without any prior communications – but far less reliable than its opposite, TCP. This Transport Layer member will perform better in streaming videos and playing online games for instance – or improve matters if you suffer with a slow internet connection to begin with – since in these cases it is preferable to have a faster connection rather than a safer one. As we previously covered, using a VPN for online gaming can bring you some benefits regarding (but not limited to) speed so setting OpenVPN with UDP for these cases will most likely suit you best.

TCP

Transmission Control Protocol on the other hand will – as its name suggests – provide a more reliable data packet transmission since it controls their flow. This is done via confirmation requests each time a single packet is transmitted from your computer to the VPN server. In other words, using TCP will ensure guaranteed packet delivery since once one is sent it will wait for confirmation that it has arrived before trying to send another one. If communication fails, TCP will keep trying to resend it until it is accepted. This results in a considerable slowdown effect on your connection since each individual data packet takes much longer than with UDP due to the extra processes. However, this means it is a more reliable transmission too, though the slowdown effect will depend on additional external factors such as the distance to the VPN server, for instance. As distance covered by the packets has a major influence, if your computer is relatively close to the server then there may not even be that much loss of speed.

Additionally there is a little trick you can do with TCP that will allow you to circumvent censorship. By setting OpenVPN on TCP port 443 your online traffic will, in short, become confused with regular SSL connections, making it very hard for websites to detect if you are using OpenVPN or a real SSL connection. This is becoming more common nowadays as many VPN providers allow you to choose TCP port 443 directly on their clients and, for those who don’t, it can be configured manually too.