TCP/UPD Connection Difference?

I've seen some VPN services offer TCP and UDP connections. I've never even been able to connect to the TCP connection, only UDP but, I'm wondering what the difference is.

Thanks

 

TCP is connection oriented, and UDP is connectionless.

TCP is you ask, you wait for an acknowledgement of asking, your get a response, other side waits to acknowledge a response.

UDP is you ask and don't wait for ack or response, and response comes whenever it comes, and doesn't wait for you to ack either. It's throwing things and hoping most of it sticks.

 

If you are streaming audio or video over the internet this will usually be done through UDP packets which are not very reliable but have less overhead, even if some packets go missing when you are streaming audio/video you will not be likely to notice it.

As far as I know TCP is normally used for data packets needing a more reliable connexion, such as acknoledgement of having received the data packet before sending the next one. When you visit a website/forum such as this one the packets you receive and send will be TCP.

If a VPN offers UDP connexion only my guess is that they are mostly targeted to people wanting to watch TV/audio online from abroad.

Pandora radio, Hulu and Crackle TV for example, are only available for US residents, I have been happily listening and watching them for a while even not being in the US, through UDP packets.

 

The connection that a VPN uses from Client to Host is independent of the data you send over it. I can watch streaming YouTube, sending UDP packets that are encapsulated via TCP. It only defines the connection type between you and the host, and does not limit the content or data or datatype that is sent over that connection.

 

Also I can add that UDP doesn't guarantee data integrity while TCP does.

 

for a VPN service UDP transport is almost always preferable. this is because multiple streams of data (of any type) are not bound to the same in-order, reliable, congestion controlled TCP VPN stream.

TCP over TCP encounters many problems due to the nested congestion control algorithms fighting against each other (to put it simply).