When is it appropriate to use UDP instead of TCP? [closed]

Answer 1

We have web service that has thousands of winforms client in as many PCs. The PCs have no connection with DB backend, all access is via the web service. So we decided to develop a central logging server that listens on a UDP port and all the clients sends an xml error log packet (using log4net UDP appender) that gets dumped to a DB table upon received. Since we don't really care if a few error logs are missed and with thousands of client it is fast with a dedicated logging service not loading the main web service.

Answer 2

The key question was related to "what kind of situations would UDP be the better choice [over tcp]"

There are many great answers above but what is lacking is any formal, objective assessment of the impact of transport uncertainty upon TCP performance.

With the massive growth of mobile applications, and the "occasionally connected" or "occasionally disconnected" paradigms that go with them, there are certainly situations where the overhead of TCP's attempts to maintain a connection when connections are hard to come by leads to a strong case for UDP and its "message oriented" nature.

Now I don't have the math/research/numbers on this, but I have produced apps that have worked more reliably using and ACK/NAK and message numbering over UDP than could be achieved with TCP when connectivity was generally poor and poor old TCP just spent it's time and my client's money just trying to connect. You get this in regional and rural areas of many western countries....

Answer 3

You want to use UDP over TCP in the cases where losing some of the data along the way will not completely ruin the data being transmitted. A lot of its uses are in real-time applications, such as gaming (i.e., FPS, where you don't always have to know where every player is at any given time, and if you lose a few packets along the way, new data will correctly tell you where the players are anyway), and real-time video streaming (one corrupt frame isn't going to ruin the viewing experience).

Answer 4

Comparing TCP with UDP, connection-less protocols like UDP assure speed, but not reliability of packet transmission. For example in video games typically don't need a reliable network but the speed is the most important and using UDP for games has the advantage of reducing network delay.

Answer 5

I'm a bit reluctant to suggest UDP when TCP could possibly work. The problem is that if TCP isn't working for some reason, because the connection is too laggy or congested, changing the application to use UDP is unlikely to help. A bad connection is bad for UDP too. TCP already does a very good job of minimizing congestion.

The only case I can think of where UDP is required is for broadcast protocols. In cases where an application involves two, known hosts, UDP will likely only offer marginal performance benefits for substantially increased costs of code complexity.

Answer 6

UDP is perfect for VoIP addressed where data packet has to be sent regard less its reliability... Video chatting is an example of UDP (you can check it by wireshark network capture during any video chatting).. Also TCP doesn't work with DNS and SNMP protocols. UDP does not have any overhead while TCP have lots of Overhead