Why protocols are necessary for network operation

You will be able to track the progress of the packages while they are in transit, and you may be required to sign for them, which provides acknowledgement of their delivery. You will also be able to contact the seller of the items if any are not delivered to arrange for re-delivery.

The four basic functions of TCP are: Ensuring data segments are delivered in the correct sequence to the correct application layer protocol. Providing flow control, so segments are delivered at a rate the receiving device can handle. Multiplexing of multiple user applications, allowing them to simultaneously access the transmission network. Error checking received segments, and requesting retransmission if segments have been corrupted.

TCP breaks up data received from the application layer into small pieces known as segments. To provide reliable transmission, the segments are numbered before being passed to the IP process, which encapsulates them into packets. TCP tracks the number of segments that are sent to a specific destination device from a specific application layer protocol. If it does not receive acknowledgement within a certain period of time, TCP assumes that the segments have been lost and will retransmit them.

TCP also checks each segment to ensure that the contents have not been changed during transmission across the network media.

This process is referred to as error checking , and is possible because each segment header includes a check-sum, which is a mathematical signature generated by feeding the data in the segment through a cyclical redundancy algorithm. This is placed in the TCP header by the sender, and the receiving device will carry out the same calculation on the data in the received segment.

If the signatures match, TCP will consider the data within the segment as not damaged. If the signatures do not match, TCP will arrange for the data to be retransmitted. TCP can serve multiple application layer protocols simultaneously, processing their data into segments and feeding them to the Internet layer in a process called multiplexing. To allow TCP to deliver received segments to the correct application layer protocol, port numbers are used. Because TCP may receive a significant number of segments, which need to be error-checked, sequenced and delivered to the correct application layer protocol, it needs to be able to control the amount of segments it receives to allow it to operate effectively.

A TCP receiving process will agree a window size with a TCP sender, which dictates the amounts of segments that can be sent before a TCP acknowledgment is sent by the receiver. The TCP receiver can thus control the amount of segments it is sent, a process called flow control. Figure 2. A simplified windowing process is illustrated in the figure below.

In a real TCP exchange, both the client and server would send data and windowing information, but for clarity only the server window size is shown. TCP windowing and flow control process View larger image.

Figure 4. The diagram below shows the same client and server exchange with a window size of However, the second segment, sequence number , is lost during transmission and is not received by the server: View larger image. Each type is necessary to use network devices swiftly and safely, and they work together to facilitate that usage.

Ad hoc networks establish a connection between two devices without an internet connection. Passive optical networks PONs bring high broadband speeds and fiber to end users' doorsteps. IT pros should know what a PON is and how it can provide network solutions. Communication protocols allow different network devices to communicate with each other. They are used in both analog and digital communications and can be used for important processes, ranging from transferring files between devices to accessing the internet.

Network management protocols define and describe the various procedures needed to effectively operate a computer network.

These include delivering a constant flow of messages to one destination called streaming and automatically making copies of a message for delivery to multiple destinations at once called broadcasting. No one protocol exists that supports all the features every computer network needs. Still, each serves as a key that unlocks a given network device or service. Different network protocols have been invented over the years, each attempting to support certain types of network communication.

The three basic characteristics that distinguish one type of protocol from another are:. The common network protocols in public use belong to the Internet Protocol family. IP is the basic protocol that enables home and other local networks across the internet to communicate with each other.

IP works well for moving individual messages from one network to another. It does not support the concept of a conversation a connection over which a stream of messages can travel in one or both directions.

HyperText Transfer Protocol is used by web browsers and servers worldwide. The internet and most other data networks work by organizing data into small pieces called packets.

To improve communication performance and reliability, each large message sent between two network devices is often subdivided into smaller packets by the underlying hardware and software. These packet switching networks require packets to be organized in specific ways according to the protocols the network supports.

This approach works well with the technology of modern networks as these handle data in the form of bits and bytes digital 1s and 0s. Each network protocol defines rules for how its data packets must be organized. Because protocols like Internet Protocol often work together in layers, some data embedded inside a packet formatted for one protocol can be in the format of some other related protocol a method called encapsulation. Protocols typically divide each packet into three parts—header, payload, and footer.

Computer networks provide a communications path within and between businesses of various types in different locations around the world. Computer networks employ various types of equipment, including routers, switches, hubs and network interface cards.

These pieces of equipment come from different vendors, but they must all work together or the network does not operate correctly. Network protocols define the rules that govern network communication. These rules determine things like packet format, type and size. They also determine what happens when an error occurs, and which part of the network is supposed to handle the error and how.