Basic networking terms and definitions

Understanding networking basics is crucial for anyone diving into the IT world. Whether you're a beginner or need a quick refresher, this glossary provides definitions of fundamental networking terms, making complex concepts easy to grasp. It covers key aspects from network infrastructure to data transmission and wireless networks.

IEEE - the Institute of Electrical and Electronics Engineers - the main organization responsible for the creation of networking standards, including Ethernet and wireless standards.

Internet - a network of networks (internetwork), cooperating with each other to exchange information using common standards.

Network Infrastructure - three categories of hardware components: end devices, intermediate devices, and network media.

Clients and Servers

End devices - PCs, laptops, servers, printers, VoIP phones, security cameras, and hand-held devices.

Hosts – end devices, connected to a network, that participate directly in network communication. Computer hosts can act as a client, a server, or both. The software installed on the computer determines which role the computer plays.

Clients - computer hosts with software that enables them to request and display the information obtained from the server.

Servers - hosts that have software installed that enables them to provide information.

Intermediary devices - routers and switches.

Data Transmission

ASCII - American Standard Code for Information Interchange (ASCII) - a commonly used code to represent and interpret letters, numbers, and special characters with bits.

Bit - “binary digit” - the smallest piece of data. Each bit can only have one of two possible values, 0 or 1. A byte – a group of eight bits.

Media - the physical medium on which the signals are transmitted.

Bandwidth - the capacity of a medium to carry data. It measures the amount of data that can flow from one place to another in a given amount of time.

Throughput - a measure of how many units of information a system can process in a given amount of time. Factors that influence throughput: the amount of data being sent and received over the connection; the types of data being transmitted; the latency. It cannot be faster than the slowest link of the path from the sending device to the receiving device.

Latency - the amount of time, including delays, for data to travel from one given point to another.

Networks

Three layers of the hierarchical network design model:

1. Access layer - a connection point for end-user devices to the network. It allows multiple hosts to connect to other hosts through a network.
2. Distribution layer - a connection point for separate networks. It controls the flow of information between the networks.
3. Core layer - a high-speed backbone layer with redundant (backup) connections. It is responsible for transporting large amounts of data between multiple end networks.

Both the physical MAC and logical IP addresses are required for a computer to communicate on a hierarchical network.

Network topology - the arrangement of the network devices and the interconnections between them.

SOHO - Small office/home office (SOHO) networks - networks installed in small offices, or homes and home offices.

Powerline networking - the ability to connect a device to the network using an adapter wherever there is an electrical outlet. The network uses existing electrical wiring to send data.

P2P – A peer-to-peer (P2P) network is a simple network of computers in which two or more PCs run both client and server software at the same time, and share files and access to devices (printers).

1. Advantages of P2P: easy to set up; less complex; good for simple tasks (transferring files, sharing printers).
2. Disadvantages of P2P: no centralized administration; not as secure; not scalable; all devices may act as both clients and servers which can slow their performance.

P2P hybrid system - resource sharing is decentralized, but the indexes that point to resource locations are stored in a centralized directory on an index server.

Wireless Networks (WLAN)

GSM - Global System for Mobile Communication - a standard developed by the European Telecommunications Standards Institute (ETSI) that specifies how 2G (second generation) cellular networks operate.

Wi-Fi Alliance - an organization that is responsible for testing wireless LAN devices from different manufacturers.

Wireless local area network (WLAN) - a self-contained network of two or more computers connected using a wireless connection.

Wi-Fi - a wireless networking technology.

A wireless networking technology uses the 2.4 GHz and 5 GHz bands.

• MIMO - multiple-input multiple-output
• MU-MIMO - multi-User MIMO
• OFDMA - orthogonal frequency-division multiple access

Bluetooth – a wireless technology that allows devices to communicate over short distances. It makes use of the 2.4 GHz band.

NFC - Near Field Communication - a wireless communication technology that enables data to be exchanged by devices that are in very close proximity to each other, usually less than a few centimeters.

SSID - Service set identifier - a sequence of characters that uniquely names a Wi-Fi network. It is a case-sensitive, alphanumeric string that contains up to 32 characters. SSID is sent in the header of all frames transmitted over the wireless local-area network (WLAN).

Hotspot - an area where Wi-Fi signals are available.

Network mode - the type of technology that must be supported (example: 802.11b, 802.11g, 802.11n, Mixed Mode).

RFIDs - Radio frequency identification tags - tags that use electromagnetic fields to automatically identify and track objects.

Wired Networks

EIA - Electronic Industries Alliance maintains standards related to wiring and connectors to ensure cabling interoperability between different devices.

Ethernet protocol - the most commonly implemented wired protocol. Ethernet protocols define how data is formatted and how it is transmitted over the wired network.

The Ethernet standards specify protocols that operate at Layer 1 (physical layer) and Layer 2 (data link layer) of the OSI model. An Ethernet LAN can connect devices using many different types of wiring media.

Ethernet protocols conform to the IEEE 802.2 and 802.3 standards.

Wiring media:

Category 5e - the most common twisted-pair wiring.

The cable is made up of 4 pairs of wires that are twisted to reduce electrical interference. The pairs of wires are colored for easy identification of the same wire at each end.

Typically, in each pair, one of the wires is a solid color and its partner is the same color striped onto a white background.

Coaxial cable – a cable with an inner wire surrounded by a tubular insulating layer, that is then surrounded by a tubular conducting shield. It is used as a high-frequency transmission line to carry high-frequency or broadband signals.

Fiber-optic cables - either glass or plastic. They can carry digital information at very high speeds over long distances.

Fiber is used in backbone networks, large enterprise environments, and large data centers.

ISP (Internet Service Provider) Services

ISP - Internet Service Provider - provides the link between the home network and the internet. It can be the local cable provider, a landline telephone service provider, the cellular network, or an independent provider (leases bandwidth on the physical network infrastructure of another company).

Cable connection - offered by cable television service providers. The data signal is carried on the coaxial cable that delivers cable television. It needs a special cable modem that separates the internet data signal from the other signals carried on the cable.

DSL connection - Digital Subscriber Line - runs over a telephone line, with the line split into three channels.

• One channel - for voice telephone calls.
• A second channel is a faster download channel, used to receive information from the internet.
• The third channel is used for sending or uploading information (usually slightly slower than the download channel).

The quality and speed of the DSL connection depend mainly on the quality of the phone line and the distance from the central office of your phone company. It requires a special high-speed modem that separates the DSL signal from the telephone signal.

Cellular internet access - uses a cell phone network. Performance depends on the capabilities of the phone and the cell tower to which it is connected.

Satellite service - requires a clear line of sight to the satellite.

Dial-up Telephone - an inexpensive option that uses any phone line and a modem.

NIC - a network interface controller - a computer hardware component that connects a computer to a network.

TCP/IP and OSI Models

OSI Model - Open Systems Interconnect Model - internetwork reference model created at the International Organization for Standardization (ISO). It defines seven layers.

TCP/IP Model - Transmission Control Protocol/Internet Protocol Model - the suite of TCP/IP protocols that are used for internet communications. It defines four layers.

Communication Protocols

IANA - The Internet Assigned Numbers Authority - is a standards organization that oversees:

1. global IP address allocation;
2. autonomous system number allocation;
3. root zone management in the Domain Name System (DNS);
4. media types and other internet protocol–related symbols and numbers.

The IANA manages and allocates blocks of IP addresses to the Regional Internet Registries (RIRs). RIRs are responsible for allocating IP addresses to ISPs that provide IPv4 address blocks to organizations and smaller ISPs.

IETF - Internet Engineering Task Force - the body that defines standard operating internet protocols such as TCP/IP.

RFC - Request for Comments – technical documentation from the IETF that includes specifications and notes about topics related to the internet and computer networking.

Protocols - the rules that govern network communications. These protocols include message format, message size, timing, encoding, encapsulation, and message patterns. Some protocols: HTTP, TCP, IP, Ethernet.

Standard - a set of rules that determines how something must be done.

Protocol stack - the interaction between the different protocols on a device. Protocol stack are illustrated as a layered hierarchy, with each higher-level protocol depending on the services of the protocols in the lower levels (TCP/IP and OSI Models).

Encapsulation - the process of adding information to the data at each layer of a protocol stack.

As the data is passed down the layers at the sending computer, delivery information gets added. At the receiving end, the data arrives at the physical layer. Each layer uses this extra information to communicate with its counterpart.

As the data is passed up the protocol stack, the headers and footers are removed. This process is called de-encapsulation.

Network Layer

A default gateway - the IP address assigned to a router or other networking device that serves as the access point for hosts on a local network to communicate with remote networks. It acts as an intermediary that forwards outbound traffic from the local network to other networks, facilitating internet and external communications.

A network prefix - a part of the IP address that identifies the specific network to which the host belongs; it is determined by the number of bits set to '1' in the subnet mask.
A network mask / a subnet mask - a 32-bit number that divides an IPv4 address into network and host portions, specifying which part of the IP address represents the network and which part represents the host within that network.

CIDR notation (Classless Inter-Domain Routing) - a method of assigning IP addresses and routing Internet Protocol packets. It allows for more efficient allocation of IP addresses than the traditional classful network design.

In CIDR notation, an IP address is followed by a slash and a number that indicates the length of the network prefix in bits.

For example, in the IPv4 address 192.0.2.0/24, the “/24” signifies that the first 24 bits are the network part of the address, leaving the remaining bits for host addresses within that network. This notation is essential for the management of address spaces and for routing traffic on the internet and within networks.

Application Layer

URI - Uniform Resource Identifier - a string of characters that identifies specific network resources and services (RESTful APIs).

URI - https://www.example.com/author/book.html#page13 (Protocol + URN + Fragment)

Parts of a URI:

• Protocol/scheme – HTTPS, FTP, SFTP, mailto, and NNTP
• Hostname - www.example.com
• Path and file name - /author/book.html
• Fragment - #page13

URL - Uniform Resource Locator - defines the network location of a specific resource on the network.

URL - https://www.example.com/author/book.html (Protocol + URN)

URN - Uniform Resource Name - This identifies only the namespace of the resource (web page, document, image, etc.) without reference to the protocol.

URN - www.example.com/author/book.html (Hostname + Path and file name)

IP Addressing Services - application layer-specific protocols designed to make it easier to obtain addresses for network devices:

• DHCP automates the assignment of IP addresses, subnet masks, gateways, and other IPv4 networking parameters.
• ARP automates the process for discovering the MAC address of the destination.
• DNS automates the process of discovering the IP address for a domain name.
• NAT automates the translation of private and public IP addresses.

Cloud and Virtualization

Cloud computing - computers, software, servers, network devices, and other services physically held at a remote location.

Virtualization - the ability to run many instances of an OS simultaneously on the same hardware platform. Virtualization is used to provide multiple servers, networks, applications, operating systems, etc. to clients.

Four primary cloud models:

1. Public clouds - cloud-based applications and services are available to the general population.
2. Private clouds - applications and services are intended for a specific organization or entity, such as the government.
3. Hybrid clouds - made up of two or more clouds (example: part private, part public), where each part remains a separate object, but both are connected using a single architecture. Individuals have degrees of access to various services based on user access rights.
4. Community clouds - for exclusive use by a specific community. The differences between public clouds and community clouds are the functional needs that have been customized for the community.

Cloud services include the following:

• SaaS – Software as a service - delivers applications over the web to end users.
• PaaS – Platform as a service - supplies tools and services used to deliver applications to end users.
• IaaS – Infrastructure as a service - provides hardware and software for companies.

Hypervisor - a program, firmware, or hardware that adds an abstraction layer on top of the physical hardware. The abstraction layer is used to create virtual machines that have access to all the hardware of the physical machine. Each of these virtual machines runs a complete and separate operating system.

Type 1 Hypervisor - the “bare metal” approach. The hypervisor is installed directly on the hardware. Type 1 hypervisors have direct access to the hardware resources and, therefore, are more efficient than hosted architectures.

Type 2 Hypervisor - software that creates and runs VM instances. Type 2 hypervisors are also called hosted hypervisors. The hypervisor is installed on top of the existing OS. Then, one or more additional OS instances are installed on top of the hypervisor.