What makes udp faster than tcp

But that's not really true. The most important thing TCP gives you is congestion control: you can run TCP connections across a DSL link all going at max speed, and all connections will be productive, because they all "sense" the available bandwidth.

Try that with different UDP applications, all pushing packets as fast as they can go, and see how well things work out for you. On a larger scale, this TCP behavior is what keeps the Internet from locking up into "congestion collapse". Group delivery semantics: it's possible to do reliable delivery to a group of people much more efficiently than TCP's point-to-point acknowledgement.

Out-of-order delivery: in lots of applications, as long as you get all the data, you don't care what order it arrives in; you can reduce app-level latency by accepting an out-of-order block.

Unfriendliness: on a LAN party, you may not care if your web browser functions nicely as long as you're blitting updates to the network as fast as you possibly can. You're on the hook for reliability now, and a lot of the things you might do to implement reliability can end up being slower than what TCP already does. This is the case when doing lots of small writes relative to the MTU size.

The reason is because TCP will try and buffer the data and fill a full network segment thus making more efficient use of the available bandwidth. UDP on the other hand puts the packet on the wire immediately thus congesting the network with lots of small packets.

You probably shouldn't use UDP unless you have a very specific reason for doing so. Especially since you can give TCP the same sort of latency as UDP by disabling the Nagle algorithm for example if you're transmitting real-time sensor data and you're not worried about congesting the network with lot's of small packets. Basically, UDP is not "loss tolerant". You can send packets to someone, and they might only get 95 of those packets, and some might be in the wrong order.

For things like video streaming, and multiplayer gaming, where it is better to miss a packet than to delay all the other packets behind it, this is the obvious choice. For most other things though, a missing or 'rearranged' packet is critical.

You'd have to write some extra code to run on top of UDP to retry if things got missed, and enforce correct order.

This would add a small bit of overhead in certain places. Think of it this way: If a packet goes missing, would you rather just get the next packet as quickly as possible and continue use UDP , or do you actually need that missing data use TCP.

The overhead won't matter unless you're in a really edge-case scenario. When speaking of "what is faster" - there are at least two very different aspects: throughput and latency. If speaking about throughput - TCP's flow control as mentioned in other answers , is extremely important and doing anything comparable over UDP, while certainly possible, would be a Big Headache tm.

As a result - using UDP when you need throughput , rarely qualifies as a good idea unless you want to get an unfair advantage over TCP. However, if speaking about latencies - the whole thing is completely different. While in the absence of packet loss TCP and UDP behave extremely similar any differences, if any, being marginal - after the packet is lost, the whole pattern changes drastically.

After any packet loss, TCP will wait for retransmit for at least ms 1sec per paragraph 2. Moreover, with TCP, even those packets which did reach destination host - will not be delivered to your app until the missing packet is received i.

And as ms is more than enough to get you killed in a fast-paced game - well, it is pretty bad for gameplay. In particular, while RUDP libraries usually avoid that "exponential backoff" and use shorter retransmit times - if they are used as a "reliable ordered" stream, they still have to suffer from Head-of-Line Blocking so in case of a double packet loss, instead of that ms we'll get about 1.

Which protocol performs better in terms of throughput - UDP or TCP - really depends on the network characteristics and the network traffic. Robert S. Barnes, for example, points out a scenario where TCP performs better small-sized writes. Senders in the network that are using TCP, will sense the 'congestion' and cut down on their sending rates. However, UDP doesn't have any congestion avoidance or congestion control mechanisms, and senders using UDP would continue to pump in data at the same rate.

Gradually, TCP senders would reduce their sending rates to bare minimum and if UDP senders have enough data to be sent over the network, they would hog up the majority of bandwidth available. So, in such a case, UDP senders will have greater throughput, as they get the bigger pie of the network bandwidth. That way, even though, each TCP connection's throughput might be limited, the sum total of the throughput of all TCP connections may be greater than the throughput for an application using UDP.

Each TCP connection requires an initial handshake before data is transmitted. Also, the TCP header contains a lot of overhead intended for different signals and message delivery detection. For a message exchange, UDP will probably suffice if a small chance of failure is acceptable. If receipt must be verified, TCP is your best option. I will just make things clear. Slow driving because something may happen to the car. While UDP just drives off, full speed no respect to street signs.

Nothing, a mad driver. UDP doesn't have error recovery, If there's an obstacle, it will just collide with it then continue. I hope this is a good example for you to understand, Why UDP is preferred in gaming. Gaming needs speed. TCP is preffered in downloads, or downloaded files may be corrupted. UDP is slightly quicker in my experience, but not by much.

The choice shouldn't be made on performance but on the message content and compression techniques. If it's a protocol with message exchange , I'd suggest that the very slight performance hit you take with TCP is more than worth it.

You're given a connection between two end points that will give you everything you need. Don't try and manufacture your own reliable two-way protocol on top of UDP unless you're really, really confident in what you're undertaking. Keep in mind that TCP usually keeps multiple messages on wire. If you want to implement this in UDP you'll have quite a lot of work if you want to do it reliably.

Your solution is either going to be less reliable, less fast or an incredible amount of work. There are valid applications of UDP, but if you're asking this question yours probably is not. It is an independent transport layer protolol, but it can be used as a library providing additional layer over UDP. The basic unit of communication is a message mapped to one or more UDP packets.

There is congestion control built in. The protocol has knobs and twiddles to switch on. It helps you to create a virtual network when multiple computer networks are connected. It is specifically designed as a model to offer highly reliable and end-to-end byte stream over an unreliable internetwork. UDP is a Datagram oriented protocol. It is used for broadcast and multicast type of network transmission. The UDP protocol works almost similar to TCP, but it throws all the error-checking stuff out, all the back-and-forth communication and deliverability.

A TCP connection is established with the help of three-way handshake. It is a process of initiating and acknowledging a connection. Once the connection is established, data transfer begins, and when the transmission process is finished, the connection is terminated by the closing of an established virtual circuit. UDP uses a simple transmission method without implied hand-shaking dialogues for ordering, reliability, or data integrity. But while TCP is instinctively reliable, its feedback mechanisms also result in a larger overhead, translating to greater use of the available bandwidth on your network.

User Datagram Protocol UDP is a simpler, connectionless Internet protocol wherein error-checking and recovery services are not required. With UDP, there is no overhead for opening a connection, maintaining a connection, or terminating a connection; data is continuously sent to the recipient, whether or not they receive it.

Overall, UDP is a much faster, simpler, and efficient protocol, however, retransmission of lost data packets is only possible with TCP. Another notable discrepancy with TCP vs UDP is that TCP provides an ordered delivery of data from user to server and vice versa , whereas UDP is not dedicated to end-to-end communications, nor does it check the readiness of the receiver requiring fewer overheads and taking up less space.

Requires an established connection to transmit data connection should be closed once transmission is complete. Connectionless protocol with no requirements for opening, maintaining, or terminating a connection. Can guarantee delivery of data to the destination router. Cannot guarantee delivery of data to the destination. Retransmission of lost packets is possible.

No retransmission of lost packets. Extensive error checking and acknowledgment of data. Basic error checking mechanism using checksums. Data is read as a byte stream; messages are transmitted to segment boundaries.

UDP packets with defined boundaries; sent individually and checked for integrity on arrival. Since TCP connection always acknowledges a set of packets whether or not the connection is totally reliable , a retransmission must occur for every negative acknowledgement where a data packet has been lost.

The flow controls from TCP, although dependable, are unable to recover missing data fast enough to be useful in real-time video communications. And while data integrity is important, it has to be balanced with speed to ensure the pace of communication remains unhindered. Additionally, Lifesize employs strategies like error concealment, error correction, and rate controls for robust UDP media connections sans lags or latency.

Lifesize strongly recommends our customers enable access via UDP toward our cloud servers, as this can help achieve the best user experience possible.