Networks (EdExcel)

Network

Network

Two or more computers or electronic devices connected for communication, using wired (cables) or wireless (Wi-Fi) mediums.

Stand-alone

A computer or device not connected to a network.

Advantages of Using Networks

Benefits include software and file sharing, hardware sharing, communication, roaming access, centralized maintenance, security, user monitoring, and levels of access.

Disadvantages of Networks

Drawbacks include cost, management requirements, spread of malware, and hacking risks.

Local Area Network (LAN)

Geographically confined network within a single site, owned and maintained by the organization.

Wide Area Network (WAN)

Spans a wide geographical area, made up of multiple LANs, used for communication and data sharing.

Wired Networks

Use copper or fiber optic cables for faster data transfer and less interference compared to wireless networks.

Wireless Networks

Use radio signals or infrared light, allowing easy addition of new nodes and user mobility.

Network Data Speeds

Measured in bits per second (bps), with 1 Mbps equal to 1,000,000 bits per second.

Formula for Calculating Transmission Time

time = size of file (in bits) / network speed (in bits).

Protocols

Rules governing communication, including Ethernet, Wi-Fi, TCP/IP, HTTP/HTTPS, and FTP.

Ethernet

A network protocol that is used in wired LANs.

Wi-Fi

A network protocol that is used in wireless LANs.

TCP/IP

A network protocol that is enables communication over the internet.

HTTP/HTTPS

A network protocol that governs web server and client communication; _____ includes secure encryption.

FTP

A network protocol that governs file transmission across a network and the internet.

Network Layering

Involves application, transport, internet, and link layers for message sending components.

SMTP

An email protocol that governs sending email to a mail server.

POP3/IMAP

An email protocol that governs retrieving emails from servers (IMAP is the newer standard).

Layering

Breaking up message sending into components/activities. Has four layers.

Application Layer

Layer in a network that encodes/decodes messages (uses HTTP, FTP, SMTP).

Transport Layer

Layer in a network that breaks messages into packets, and assigns numbers for reassembly.

Internet Layer

Layer in a network that adds IP addresses for routing and is sometimes called the network layer.

Link Layer

Layer in a network that handles physical transfer of packets between nodes.

IP Addressing

Uses IPv4 (32 bits) and IPv6 (128 bits) for node addresses.

Packet Switching

Breaks messages into packets for transmission, consisting of headers and payloads. Has two parts.

Header

Part of a packet that includes sender/recipient IP, packet number, total packets, and protocol details.

Payload

Part of a packet that is a part of the message itself.

Network Topologies

The arrangement, or pattern, in which all nodes on a network are connected together. The major network topologies are Bus, Ring, Star, and Mesh.

Node

Any device connected to a network, either by cables or wirelessly.

Bus Networks

All nodes joined to a single cable. At each end of the cable, a terminator is fitted to stop signals reflecting back down the bus.

Star Networks

Nodes connected through one or more switches/hubs. The switch or hub acts as a central point through which all communications are passed.

Hub

Broadcasts a message across the whole network.

Switch

Sends the message to the intended recipient only.

Mesh Networks

Nodes connected to multiple other nodes without a central connection point, offering reliability and multiple communication routes.