How to understand network protocols?

Question

I work in web development, but I don\'t have a great understanding of network protocols. I recall hearing an analogy that TCP, HTTP, and SSL can be thought of as a series of

Answer 1

Network protocols are formal standards and policies comprised of rules, procedures and formats that define communication between two or more devices over a network. Network protocols govern the end-to-end processes of timely, secure and managed data or network communication.

There are several broad types of networking protocols, including:

• Network communication protocols: Basic data communication protocols, such as TCP/IP and HTTP.

• Network security protocols: Implement security over network communications and include HTTPS, SSL and SFTP.

• Network management protocols: Provide network governance and maintenance and include SNMP and ICMP.

The different layers of the Open Systems Interconnection (OSI) reference model are:

1. Application layer: This is the upper most layer in the OSI reference model. The application layer provides the means by which application processes can access network services, and is therefore associated with services that include direct support for applications.

2. Presentation layer: This layer in the OSI reference model deals with specifying the format which should be utilized to enable network data to be communicated between computers in the network. The presentation layer adds formatting, encryption, and data compression to the packet.

3. Session layer: This layer enables applications that reside on different computers to create and close network sessions. It also manages open network connections, or sessions that are open.

4. Transport layer: The transport layer is responsible for ensuring that data is delivered in sequence, error-free, and efficiently over the network. The transport layer also identifies duplicated packets, and drops them. Transport layer protocols include Transmission Control Protocol (TCP) and Sequenced Packet Exchange (SPX). These protocols open packets at the receiving computer, and reassemble the original messages as well.

5. Network layer: This layer of the OSI reference model provides addressing for messages for all networks. It translates your logical addresses and names to physical addresses, and then identifies the preferred route from the source computer to the destination computer.

6. Data Link layer: The Data Link layer prepares data for the physical connection by defining the means by which software drivers can access the physical medium. The Data Link layer transmits frames from the Network layer to the Physical layer.

7. Physical layer: This layer places the data on the physical medium which is carrying the data. It is responsible for the actual physical connection between two computers on the network that are exchanging data.

The function of protocols at the sending computer is summarized below:

• Segment data into smaller more manageable chunks or packets.

• Append addressing to the packets.

• Ensure that data is ready for sending via the network interface card (NIC) to the network cable

The function of protocols at the receiving computer is summarized below:

• Remove packets from the network cable, and move the packets through the NIC to the computer.

• Remove all information that relate to the sending of the packet. This is information added to the packet by the sending computer.

• Move the packets to the buffer for the reassembly process.

• Convey the data to the particular application.

Internet Protocol :

Internet protocol suite is the set of communication protocols that implement the protocol stack on which the internet runs. The Internet protocol suite is sometimes called the TCP/IP protocol suite, after TCP\IP, which refers to the important protocols in it, the Transmission Control Protocol(TCP) and the Internet Protocol(IP). The Internet protocol suite can be described by the analogy with the OSI model, but there are some differences. Also not all of the layers correspond well.

Protocol Stack:

A protocol stack is the complete set of protocol layers that work together to provide networking capabilities.

Transmission Control Protocol (TCP):

The Transmission Control Protocol is the core protocol of the internet protocol suite. It originated in the network implementation in which it complemented the Internet Protocol. Therefore the entire suite is commonly referred to as TCP/IP. TCP provides reliable delivery of a stream of octets over an IP network. Ordering and error-checking are main characteristics of the TCP. All major Internet applications such as World Wide Web, email and file transfer rely on TCP.

Internet Protocol(IP):

The Internet Protocol is the principal protocol in the Internet protocol suite for relaying data across networks. Its routing function essentially establishes the internet. Historically it was the connectionless datagram service in the original Transmission Control Program; the other being the connection oriented protocol(TCP). Therefore, the Internet protocol suite is referred as TCP/IP.