What are protocols in networking

Protocols are a set of standards that allow network devices to communicate and exchange information. Protocols define how devices start, manage and end communication; most protocols are described by IETF (Internet Engineering Task Force) as RFC’s (Request for Comments).

Protocols are set of rules for communication. In a computer network, all computers need to use the same protocol for communication. Protocols may include signalling, authentication and error detection and correction capabilities. Protocols address data formats, address formats, error detection techniques, sequence & flow control, routing and other requirements for communication. In a network, multiple protocols are used during communication. Examples of protocols at the network layer are Net BEUI, IPX/SPX, TCP/IP, Apple Talk, etc.

The NetBEUI protocol is used to connect and communicate between computers with Microsoft Windows as the operating system. Similarly Apple Talk protocol is used to connect and communicate among computers with MAC OS. However, when connecting computers with different operating systems you need to use a standardized protocol such as the TCP/IP protocol.

Proprietary & Open Standard Protocols

Proprietary protocols are communications protocol owned by a single organization or individuals. Usually proprietors enforce technical and licensing restrictions through patents to keep the specification as a trade secret. Examples include NETBEUI from Microsoft, IPX/SPX from Novell, AppleTalk from Apple, etc.

Open Standard protocols are communication protocols that are publicly available,have various rights to use associated with it, and may also have various properties of how it was designed. Example, TCP/IP.


NetBEUI is a non-routable protocol used for Microsoft Networks. NetBEUI (NetBIOS Extended User Interface) is ideal for small networks. In this protocol, each device must have a unique name (referred to as the workstation name) of max 15 character length. NetBEUI is not efficient on large networks or routable, hence it is not used much today.


IPX/SPX (Internetwork Packet Exchange/Sequenced Packet Exchange) is a routable protocol used in Novell NetWare networks. IPX operates at the Network Layer and SPX at the Transport Layer. NWLink IPX/SPX is a protocol developed by Microsoft that is compatible with IPX/SPX Protocol.


AppleTalk is a proprietary suite of networking protocols developed by Apple Inc. for their Mac computers. AppleTalk included a number of features that allowed local area networks to be connected with no prior setup or the need for a centralized router or server of any sort. Connecting together AppleTalk equipped systems would automatically assign addresses, update the distributed namespace, and configure any required inter-networking routing. It is a plug-n-play system.


TCP/IP (Transmission Control Protocol/Internet Protocol) is a routable protocol suite that is also known as the Core Protocol of the Internet Protocol Suite. TCP/IP has gained popularity as it is very efficient in very large networks; most operating systems include support for TCP/IP.

Unlike many other protocols, TCP/IP have the following benefits:

  • Open Standard (not tied to any vendor unlike proprietary protocols)
  • Enable communication between different Operating Systems (almost everyoperating system including flavors of Unix, Windows, Mac OS support TCP/IP)
  • Runs on any network framework (Ethernet, Token Ring, Dial-Up connections)
  • Routable & a common addressing scheme.

TCP/IP protocol suite is the most widely used protocol today including LAN’s and .WAN’s. Internet uses TCP/IP as its protocol.


Internet Protocol is the primary communication protocol used for relaying data across network boundaries. Functions include logical addressing and routing. The first major version of IP, Internet Protocol Version 4 (IPv4), is the dominant protocol of the internet. Its successor is Internet Protocol Version 6 (IPv6), which is increasingly being used.


IPv4 is a connectionless protocol for use on packet-switched Link Layer networks (e.g., Ethernet). It operates on a best effort delivery model; in that it does not guarantee delivery, nor does it assure proper sequencing or avoidance of duplicate delivery. These aspects, including data integrity, are addressed by an upper layer transport protocol, such as the Transmission Control Protocol (TCP).

IP (IPv4) use a 32-bit address that will provide 4,294,967,296 (2ยน2) possible addresses and has two parts: Network ID (Portion of the address that represents the network that a device belongs to) and Host ID (Portion of the address that represents the host on a particular network). Network & Host portion of an IP address is decided based on an additional value called the Subnet Mask. Each device on an IP network must have a unique IP address for communication.

IP addresses are binary numbers (image below), but they are usually stored in text files and displayed in human-readable notations such as (image below).

Decimal Notation vs Binary Notation


Internet Assigned Numbers Authority (IANA) is the entity that oversees global IP address allocation, autonomous system number allocation, root zone management in the Domain Name System (DNS), media types, and other Internet Protocol related symbols and numbers. IANA is a department operated by the Internet Corporation for Assigned Names and Numbers, also known as ICANN.

The Internet Assigned Numbers Authority (IANA) manages the IP address space allocations globally and delegates five regional Internet registries (RIRs) to allocate IP address blocks to local Internet registries (Internet service providers) and other entities.

Classful Network

Classful network is an addressing schedule originally introduced in 1981 and used for several years until the introduction of CIDR method. In this method, the 32-bit address space is divided into five addresses classes namely A, B, C, D and E. Each class defines a fixed network size and number of hosts within networks.

Following table summarises the classes of IPv4 addressing:

ClassRangeSubnetNo. Of NetworksNo. Of Hosts / N
A0.0.0.0-, 777,214
B128.0.0.0-,38465, 532
E240.0.0.0- for future use

Examples of Class A IP Addresses:,,

Examples of Class B IP Addresses:,,

Examples of Class C IP Addresses:,,

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