Why is connectionless

In the other hand, connectionless protocol means that we don't need to establish connection to send data. It means the first packet being sent from one host to another could contain data payloads. Of course for upper layer protocols such as UDP, the recipient must be ready first, e. In my knowledge, every layer makes a fool of the one above it. Lets call them data packets. Now, TCP after sending a packet, waits for an acknowledgement packet from the other side.

If it comes, it says the above layer, hey, I have established a connection and now we can communicate! The whole communication process goes on between the TCP layers on both the sides sending and receiving different types of packets with each other such as data packet, acknowledgement packet, synchronization packet , blah blah packet.

It uses other tricks all packet sending to ensure the actual data packets to be delivered in ordered as they were broken and assembled. After assembling, it transfers them to the above application layer.

That fool thinks that it has got an HTTP message in an established connection but in reality, just packets are being transferred. I just came across this question today. It was bouncing around in my head all day and didn't make any sense. IP doesn't handle transport. Why would anyone even think of IP as connectionless or connection oriented? It is technically connectionless because it offers no reliability, no guaranteed delivery.

But so is my toaster. My toaster offers no guaranteed delivery, so why not call aa toaster connectionless too? In the end, I found out it's just some stupid title that someone somewhere attached to IP and it stuck, and now everyone calls IP connectionless and has no good reason for it.

Calling IP connectionless implies there is another layer 3 protocol that is connection oriented, but as far as I know, there isn't and it is just plain stupid to specify that IP is connectionless. MAC is connectionless. LLC is connectionless.

But that is useless, technically correct info. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow.

Learn more. Ask Question. Asked 10 years, 10 months ago. Active 5 years, 3 months ago. Viewed 23k times. Improve this question. There's no real guarantee of packet ordering or delivery in a virtual circuit.

You still need sequence numbers. Add a comment. Active Oldest Votes. By itself, IP gives: no assurance that it'll be delivered no way to find out if it was nothing to let the destination know to expect a packet much of anything else All it does is specify a minimal packet format so you can get some data from one point to another e. Improve this answer.

Jerry Coffin Jerry Coffin k 74 74 gold badges silver badges bronze badges. As you said, establishing a connection involves allocating some memory and some other things happening on both ends. So is that all about connection? Is there anything else involved in the middle of the 2 ends? User Datagram Protocol UDP is a connectionless protocol used for less complex transmissions, TCP is the more complex protocol, used for connection-oriented transmissions based on its stateful design incorporating data stream services and reliable transmission.

Services are the operations that any given layer in the OSI Reference model is able to provide to the layer above it. A service defines the operation itself that a layer can perform, but the service does not specify any details of implementation. In the transport layer, data on the host computers is delivered to the appropriate application processes.

The port numbers together with the source and destination IP addresses constitute a network socket—an address for identification of the process-to-process communication. The session layer supports this function in the OSI model. This means these protocols provide connection-oriented communication using a packet-oriented network. TCP also supports error recovery for end-to-end reliable communication through error detecting code and automatic repeat request ARQ protocol.

The much simpler UDP protocol uses packets called datagrams instead of segments. It does not provide reliable communication or virtual circuits. These differences mean that TCP may be used for various protocols, including email transfer and HTTP web browsing, while UDP is more likely to be used for functions such as broadcasting and multicasting, where retransmission to many hosts is not possible.

Offering shorter latency, higher throughput, lower costs, and other benefits of connectionless communication, UDP is often used when packet loss can occasionally be accepted during real-time multimedia communication—for example, for online computer games, IP-TV, and IP-telephony. Datagrams are referring to connectionless protocols. A connectionless protocol layer lacks an acknowledgment scheme and sequence number, meaning the protocol is connectionless. However, it can also be called datagram.

Clients and servers that use a perfect channel to communicate share a dedicated point-to-point channel—or an illusory version of such a connection. First, the client and server must establish the connection to communicate and transmit the data, afterwards closing the connection. The channel guarantees that all data transmitted over the channel is sent and received in the same order.

When clients and servers use datagrams to communicate, they send and receive completely independent packets over the network. The packets do not have a dedicated point-to-point channel and travel on whatever route is available. In contrast, a connection-oriented protocol layer has an expected acknowledgment process and sequence numbers, and if they are not received, retransmission takes place. This is how connection-oriented protocols guarantee delivery of data.

They are more reliable protocols. TCP works based on a set of rules and uses them to negotiate before establishing a logical connection and sending the data. It is therefore used for applications that demand these types of connections and service features.

By not negotiating and then establishing a connection, the UDP saves time. Applications perform any handshake necessary for ensuring orderly release. Examples of services that use connection-oriented transport services are telnet , rlogin , and ftp. Connectionless protocols, in contrast, allow data to be exchanged without setting up a link between processes. Each unit of data, with all the necessary information to route it to the intended destination, is transferred independent of other data packets and can travel over different paths to reach the final destination.

Some data packets might be lost in transmission or might arrive out of sequence to other data packets. UDP is a connectionless protocol.

It is known as a datagram protocol because it is analogous to sending a letter where you don't acknowledge receipt. Examples of applications that use connectionless transport services are broadcasting and tftp. The application developer must decide which type of protocol works best for the particular application.