Introduction to Data Networks

• A network involves two or more connected entities.
• Data networks of machines are of primary interest.

Data Network Objectives

• Data and information sharing.
• Resource sharing, including printers and fax machines.
• Facilitating communication.

Data Network Advantages

• Cost reduction.
• Time savings.
• Faster and easier communication.
• Networks enable communication between people.
• The Internet has become essential in daily life.

How Networks Support Communication

• Instant messaging (IM) enables real-time conversations.
• Weblogs (Blogs) offer easily updatable and editable web pages.
• Wikis allow collaborative editing and viewing of web pages.
• Podcasting distributes recordings to a broad audience.
• Collaboration tools facilitate teamwork on shared documents.

How Networks Support Learning

• E-learning, also known as distance learning, expands access to education.
• Online courses are accessible anytime, anywhere.
• Online courseware benefits include:
  • Current training materials.
  • Wide audience availability.
  • Consistent instruction quality.
  • Cost reduction.
• Networks also support online games.

Network Characteristics

• Size refers to the area covered by the network.
• Topology describes the physical and logical arrangement of the network.

Network Size Classifications

• PAN (Personal Area Network)
• LAN (Local Area Network)
• MAN (Metropolitan Area Network)
• WAN (Wide Area Network)

PAN Details

• PANs cover a limited area, like a room or house.
• PANs connect 5 to 10 devices.

LAN Details

• LANs cover a single geographical area such as a building, campus, or region.
• A single organization typically administers LANs.

WAN Details

• WANs link multiple locations separated by significant geographical distances.
• Telecommunications service providers (TSPs) might be needed to connect LANs in a WAN.

Internet Details

• The Internet is a global network of interconnected networks.
• The Internet is the most widely used, publicly accessible internetwork.
• The Internet is created by connecting networks of Internet Service Providers (ISPs).
• ISP networks interconnect to provide access for millions globally.

Intranet and Extranet Details

• Intranets are private networks used by a single company for internal communication and transactions among employees and branches, accessible only to authorized members and employees.
• Extranets are extended internetworks offering limited access to corporate data for suppliers, vendors, and customers.

Network Topology Details

• Physical topology is the network's physical layout and how devices are connected.
• Logical topology defines how devices communicate within the network.

Common Physical Topologies

• BUS
• Star
• Extended Star
• Ring
• Mesh (Full or Partial)
• Tree

Common Logical Topologies

• BUS
• Star
• Ring
• Mesh

Basic Network Elements

• Rules
• Medium
• Messages
• Devices
• Services

Rules and Protocols

• Rules or agreements are established to govern communication.
• Protocols must be followed for successful message delivery and understanding.
• Successful human communication protocols include:
  • Identified sender and receiver.
  • Communication method (face-to-face, telephone, etc.).
  • Common language and grammar.
  • Speed and timing of delivery.
  • Confirmation or acknowledgement requirements.

Medium Types

• Copper medium: Twisted pair telephone wire, coaxial cable, unshielded twisted pair (UTP) cable.
• Optical fibers: Thin strands of glass or plastic that carry light signals.
• Wireless medium: WiFi, satellites, cellular networks.

Criteria for Choosing a Network Medium

• Distance
• Environment
• Data amount to be transmitted and speed
• Cost of media and installation

Messages

• Data is sent in messages across the network medium from source to destination.

Network Devices

• End devices (hosts, peripherals, users).
• Intermediary devices (connecting devices).
• Examples of end devices include computers, laptops, servers, network printers, IP phones, IP cameras, and mobile handheld devices.
• A host can be the source or destination of a message.
• Intermediary devices connect hosts to the network and form internetworks.
• Connecting devices include hubs, switches, wireless access points, routers, modems, and firewalls.

Important Networking Terms

• Network Interface Card (NIC or LAN adapter): Provides the physical network connection at the PC or host device.
• Physical Port: A connector or outlet on a networking device used for media connection.
• Interface: Specialized ports on internetworking devices, such as routers, that connect individual networks.
• Straight-through Cable: UTP copper cable for connecting dissimilar networking devices.
• Crossover Cable: UTP copper cable for connecting similar networking devices.
• Serial Cable: Copper cable suitable for wide area connections.

Network Services

• World Wide Web (www)
• E-Mail
• Instant Messaging (IM)
• IP Telephony (IPT)

Communication Types

• Unicast is data sent from one device to a single destination.
• Multicast is data sent from one device to a group of devices.
• Broadcast is data sent from one device to all devices on the network.

Communication Modes

• Simplex allows one-way signal transmission.
• Half-duplex allows transmission in both directions, but not simultaneously.
• Full-duplex allows simultaneous transmission in both directions.

Converged Networks

• Traditional networks (telephone, radio, television, data) have separate infrastructures.
• Technology enables consolidating these networks onto a single platform, known as a Converged Network.
• Converged Networks eliminate the need for separate networks.

Well-Designed Network Characteristics

• Fault tolerance: Enables the network to continue operating despite component failures.
• Scalability: Allows the network to expand quickly without impacting performance.
• Quality of Service (QoS): Provides good quality and uninterrupted delivery, critical for voice and video.
• Security: Protects information confidentiality and restricts unauthorized access.