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Internet Protocol (IP)

Internet Protocol (IP) is a fundamental set of rules that governs the format of data sent over the Internet or local networks. The primary function of IP is to deliver packets from the source host to the destination host solely based on the IP addresses in the packet headers. For this reason, IP defines packet structures that encapsulate the data to be delivered, as well as addressing methods that label the datagram with source and destination information.

Internet Protocol Suite: TCP/IP

The Internet Protocol Suite, commonly referred to as TCP/IP, is the conceptual model and set of communications protocols used on the Internet and similar networks. It gets its name from two of its most important protocols: the Transmission Control Protocol (TCP) and the Internet Protocol (IP). This suite is a layered communication protocol suite that organizes protocols into four abstraction layers, which are, from lowest to highest: the link layer, the internet layer, the transport layer, and the application layer.

Layers of the Internet Protocol Suite

  1. Link Layer: This is the lowest layer of the protocol suite and is responsible for the physical transmission of data over network interfaces. It encompasses all the methods used to move data between two devices on the same network.

  2. Internet Layer: The internet layer, primarily consisting of the Internet Protocol, is responsible for packet forwarding, including routing through intermediate routers.

  3. Transport Layer: This layer provides host-to-host communication services for applications. The most commonly used transport protocols are TCP and UDP (User Datagram Protocol). TCP provides reliable, ordered, and error-checked delivery of a stream of data between applications, while UDP offers a simpler, connectionless datagram service.

  4. Application Layer: This layer contains all protocols that support user applications. Common protocols at this layer include HTTP (HyperText Transfer Protocol), FTP (File Transfer Protocol), SMTP (Simple Mail Transfer Protocol), and DNS (Domain Name System).

IP Addressing

An IP address is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. An IP address serves two main functions: identifying the host or network interface and providing the location of the host in the network, thus enabling routing.

Versions of IP

There are two versions of the Internet Protocol in use today:

  • IPv4: This is the first version of IP to be used in production environments. IPv4 uses a 32-bit address scheme, allowing for a total of 2^32 addresses (just over 4 billion addresses).

  • IPv6: Due to IPv4 address exhaustion, IPv6 was developed to enable the expansion of the internet. IPv6 uses a 128-bit address scheme, vastly increasing the number of available addresses.

Network Address Translation

Network Address Translation (NAT) is a method of remapping one IP address space into another by modifying network address information in the IP header of packets while they are in transit across a traffic routing device. This is used to improve security and decrease the number of IP addresses an organization needs.

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