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What is TCP/IP, and How Does it Work?



This article will discuss TCP/IP and its Layers, Packet transport, routing, and SYN/ACK flags. Understanding what is TCP/IP and how it works is essential in any modern environment. Therefore, we recommend reading this article before learning about internet protocols for those new to the subject.

Layers of TCP/IP

TCP/IP is an acronym for Transport Control Protocol and Internet Protocol. It allows data packets to travel across the Internet. It is a GPS for the packets passing through gateway computers that forward data to the destination. Layers below the top layer determine how data is sent and received.

TCP/IP works by breaking down the various communication tasks into different layers. Each layer serves a specific purpose. For example, the top layer, TCP, compiles large amounts of data into packets and sends them to another TCP layer for conversion into useful information. After the packets have passed through all four layers, they are reassembled back into the original format for the recipient.


You may be wondering what the purpose of routing in TCP/IP is and how it works. Routing is the process of determining the next hop of a packet. Routers use a table called a routing table to determine the best possible path for a pass is repeated until the packet reaches its final destination. In each process step, the router reads the headers of the packets to determine which route to take.

There are two basic types of routing in TCP/IP. These are static and dynamic. Static routing requires manual maintenance and is helpful for single networks and two-way communication. Dynamic routing uses daemons to update the routing table. These daemons constantly receive and process information from other gateways. This is the more efficient routing method. In large networks, dynamic routing is recommended. In small networks, static routing is usually used.

Packet transport

TCP/IP and packet transport are separate protocols that manage the delivery of data over the Internet. Both protocols pass segments or packets from the physical network to the IP layer. First, the IP protocol prepares components for delivery by formatting them into units called IP datagrams. This step determines which IP addresses belong to the sending and receiving hosts. Next, an IP header is attached to each segment. The IP header contains information such as the datagram’s size, sequence order, and length.

TCP and IP work together to make the Internet work. Without one another, the Internet wouldn’t exist. This is because TCP depends on IP for addressing, allowing long data streams to be separated into packages and sent through the network. While IP works on a best-effort basis, packets can get lost en route or arrive out of sequence. TCP addresses these problems by splitting the data stream into several smaller packets.

SYN/ACK flags

SYN/ACK flags are bits in TCP/IP packets. A server responds to an SYN flag with a sequence number of zero and acknowledges that it received the SYN flag. The next segment, called an ACK, indicates the client has received the SYN flag and expects to receive a response at sequence number 100.

The SYN flag is cleared when the first data byte is received. The ACK flag sets when the following sequence number is expected. After receiving a data byte, the ACK flag indicates the packet is complete, and the receiving application should acknowledge the data. The ACK flag must be set after the client sends the initial SYN packet.

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