Networking Today Notes

Networks Affect Our Lives

  • Communication relies heavily on networks, connecting us globally.
  • Networks support learning, communication, work, and play without boundaries.

Network Components

  • Host/End Device: Any computer on a network.
  • Servers: Provide information to end devices.
    • Email servers
    • Web servers
    • File servers
  • Clients: Send requests to servers to retrieve information.
    • Web page from a web server
    • Email from an email server

Host Roles - Server Types

  • Email:
    • Description: Email server runs email server software; clients use client software to access email.
  • Web:
    • Description: Web server runs web server software; clients use browser software to access web pages.
  • File:
    • Description: File server stores corporate and user files; client devices access these files.

Peer-to-Peer Networks

  • Devices can function as both client and server.
  • Recommended only for very small networks.
  • Advantages:
    • Easy to set up.
    • Less complex.
    • Lower cost.
  • Disadvantages:
    • No centralized administration.
    • Not as secure.
    • Not scalable.
    • Slower performance.
  • Used for simple tasks like file transfer and printer sharing.

End Devices

  • Message origin or destination.
  • Data originates and arrives at an end device, flowing through the network.

Intermediary Network Devices

  • Interconnect end devices.
  • Examples: switches, wireless access points, routers, firewalls.
  • Roles:
    • Regenerate and retransmit data signals.
    • Maintain information about network pathways.
    • Notify other devices of errors and communication failures.

Network Media

  • Carries communication across a network from source to destination.
  • Media Types:
    • Metal wires (cables): Use electrical impulses.
    • Glass/Plastic fibers (fiber-optic cable): Use pulses of light.
    • Wireless transmission: Uses modulation of specific frequencies of electromagnetic waves.

Network Representations and Topologies

Network Representations

  • Network diagrams (topology diagrams) use symbols to represent devices.
  • Key terms:
    • Network Interface Card (NIC)
    • Physical Port
    • Interface (often used interchangeably with 'port')

Topology Diagrams

  • Physical topology:
    • Illustrates the physical location of intermediary devices and cable installation.
  • Logical topology:
    • Illustrates devices, ports, and the addressing scheme of the network.

Common Types of Networks

Networks of Many Sizes

  • Small Home Networks: Connect a few computers to each other and the Internet.
  • Small Office/Home Office (SOHO): Connects computers within a home or remote office to a corporate network.
  • Medium to Large Networks: Many locations with hundreds or thousands of interconnected computers.
  • World Wide Networks: Connects hundreds of millions of computers worldwide, like the Internet.

LANs and WANs

  • Network infrastructures vary greatly in terms of:
    • Size of area covered
    • Number of users connected
    • Number and types of services available
    • Area of responsibility
  • Two most common types:
    • Local Area Network (LAN)
    • Wide Area Network (WAN)

LANs and WANs (cont.)

  • LAN:
    • Spans a small geographical area.
    • Interconnects end devices in a limited area.
    • Administered by a single organization or individual.
    • Provides high-speed bandwidth to internal devices.
  • WAN:
    • Spans a wide geographical area.
    • Interconnects LANs over wide geographical areas.
    • Typically administered by one or more service providers.
    • Typically provides slower speed links between LANs.

The Internet

  • A worldwide collection of interconnected LANs and WANs.
  • LANs connect to each other using WANs.
  • WANs may use copper wires, fiber optic cables, and wireless transmissions.
  • The Internet is not owned by anyone.
  • Organizations that maintain structure on the internet:
    • IETF
    • ICANN
    • IAB

Intranets and Extranets

  • Intranet: A private collection of LANs and WANs internal to an organization, accessible only to its members or authorized individuals.
  • Extranet: Provides secure access to an organization's network for individuals working for a different organization who need access to their data.

Internet Connections

Internet Access Technologies

  • Various ways to connect users and organizations to the Internet:
    • Broadband cable
    • Broadband digital subscriber line (DSL)
    • Wireless WANs
    • Mobile services
    • Business DSL
    • Leased lines
    • Metro Ethernet

Home and Small Office Internet Connections

  • Cable: High bandwidth, always-on internet via cable television service providers.
  • DSL: High bandwidth, always-on internet over telephone lines.
  • Cellular: Uses a cell phone network.
  • Satellite: For rural areas lacking Internet Service Providers.
  • Dial-up: Inexpensive, low bandwidth option using a modem.

Businesses Internet Connections

  • Corporate business connections often require:
    • Higher bandwidth
    • Dedicated connections
    • Managed services
  • Types of Connection:
    • Dedicated Leased Line: Reserved circuits within the service provider’s network.
    • Ethernet WAN: Extends LAN access technology into the WAN.
    • DSL: Business DSL formats including Symmetric Digital Subscriber Lines (SDSL).
    • Satellite: Use when wired solutions are unavailable.

The Converging Network

  • Before converged networks, organizations used separate cabling for telephone, video, and data.
  • Each network used different technologies, rules, and standards.

The Converging Network (Cont.)

  • Converged data networks carry multiple services on one link including data, voice and video.
  • Converged networks deliver data, voice, and video over the same network infrastructure using the same rules and standards.

Reliable Networks

Network Architecture

  • Technologies that support the infrastructure that moves data across the network.
  • Four basic characteristics needed to meet user expectations:
    • Fault Tolerance
    • Scalability
    • Quality of Service (QoS)
    • Security

Fault Tolerance

  • Limits the impact of failure by limiting the number of affected devices.
  • Requires multiple paths for redundancy.
  • Achieved by implementing a packet-switched network.
    • Packet switching splits traffic into packets routed over a network.
    • Each packet can take a different path to the destination.
    • Not possible with circuit-switched networks which establish dedicated circuits.

Scalability

  • Expand quickly and easily to support new users and applications without impacting existing user services.
  • Network designers follow accepted standards and protocols to make networks scalable.

Quality of Service

  • Ensures reliable delivery of content, especially for voice and live video.
  • Higher expectations for voice and live video transmissions.
  • QoS manages the flow of data and voice traffic when bandwidth demand is high.

Network Security

  • Two main types:
    • Network infrastructure security
      • Physical security of network devices.
      • Preventing unauthorized access.
    • Information Security
      • Protection of data transmitted over the network.
  • Three goals:
    • Confidentiality: Only intended recipients can read the data.
    • Integrity: Data has not been altered during transmission.
    • Availability: Timely and reliable access to data for authorized users.

Network Trends

Recent Trends

  • The role of the network must adjust and continually transform to keep up with new technologies and end-user devices.
  • Several networking trends affecting organizations and consumers:
    • Bring Your Own Device (BYOD)
    • Online collaboration
    • Video communications
    • Cloud computing

Bring Your Own Device

  • Allows users to use their own devices, providing more opportunities and flexibility.
  • Freedom to use personal tools to access information and communicate using laptops, netbooks, tablets, smartphones, e-readers.
  • BYOD means any device, with any ownership, used anywhere.

Online Collaboration

  • Collaboration tools (e.g., Cisco WebEx) allow users to instantly connect and interact.
  • Collaboration is a high priority for businesses and education.
  • Cisco Webex Teams is a multifunctional collaboration tool for sending instant messages, posting images, videos, and links.

Video Communication

  • Video calls can be made to anyone, regardless of location.
  • Video conferencing is a powerful communication tool.
  • Video is becoming a critical requirement for effective collaboration.
  • Cisco TelePresence powers a way of working where everyone, everywhere.

Cloud Computing

  • Allows storage of personal files or data backup on servers over the internet.
  • Applications can also be accessed using the Cloud.
  • Enables businesses to deliver services to any device, anywhere in the world.
  • Made possible by data centers.
  • Smaller companies lease server and storage services from larger data center organizations in the Cloud.

Cloud Computing (Cont.)

  • Four types of Clouds:
    • Public Clouds: Available to the general public through a pay-per-use model or for free.
    • Private Clouds: Intended for a specific organization or entity (e.g., government).
    • Hybrid Clouds: Made up of two or more Cloud types (e.g., custom and public), each remaining distinctive but connected using the same architecture.
    • Custom Clouds: Built to meet the needs of a specific industry (e.g., healthcare or media), can be private or public.

Technology Trends in the Home

  • Smart home technology integrates technology into everyday appliances, allowing them to interconnect with other devices.
  • Ovens communicate with calendars to know when to cook a meal.
  • Smart home technology is being developed for all rooms within a house.

Powerline Networking

  • Allows devices to connect to a LAN where data network cables or wireless communications are not viable.
  • Devices connect to the LAN via electrical outlets, sending data on certain frequencies using a standard powerline adapter.
  • Useful when wireless access points cannot reach all devices in the home.

Wireless Broadband

  • Another option, in addition to DSL and cable, to connect homes and small businesses to the internet.
  • Wireless Internet Service Provider (WISP) connects subscribers to designated access points or hotspots, commonly found in rural environments.
  • Uses the same cellular technology as smartphones.
  • An antenna is installed outside the house, providing wireless or wired connectivity for devices in the home.

Network Security

Security Threats

  • Integral part of networking, regardless of network size.
  • The network security that is implemented must account for the environment while securing the data and also allowing for expected quality of service.
  • Involves protocols, technologies, devices, tools, and techniques to secure data and mitigate threats.
  • Threat vectors: External or internal.

Security Threats (Cont.)

  • External Threats:
    • Viruses, worms, and Trojan horses
    • Spyware and adware
    • Zero-day attacks
    • Threat Actor attacks
    • Denial of service attacks
    • Data interception and theft
    • Identity theft
  • Internal Threats:
    • Lost or stolen devices
    • Accidental misuse by employees
    • Malicious employees

Security Solutions

  • Security must be implemented in multiple layers using more than one security solution.
  • Network security components for home or small office networks:
    • Antivirus and antispyware software on end devices.
    • Firewall filtering to block unauthorized access.

Security Solutions (Cont.)

  • Larger networks have additional security requirements:
    • Dedicated firewall system
    • Access control lists (ACL)
    • Intrusion prevention systems (IPS)
    • Virtual private networks (VPN)
  • The study of network security starts with an understanding of the underlying switching and routing infrastructure.

The IT Professional

CCNA

  • The Cisco Certified Network Associate (CCNA) certification:
    • Demonstrates knowledge of foundational technologies.
    • Ensures relevance with skills needed for the adoption of next-generation technologies.
  • The new CCNA focus:
    • IP foundation and security topics
    • Wireless, virtualization, automation, and network programmability.
  • New DevNet certifications at the associate, specialist, and professional levels to validate software development skills.
  • Specialist certifications validate skills in line with the job role and interests.

Networking Jobs

  • Find employment opportunities by using the Talent Bridge Matching Engine at www.netacad.com.
  • Search for jobs with Cisco, Cisco partners, and distributors seeking Cisco Networking Academy students and alumni.

Summary of Main Teaching Points

  • Explain how multiple networks are used in everyday life.
  • Describe the topologies and devices used in a small to medium-sized business network.
  • Explain the basic characteristics of a network that supports communication in a small to medium-sized business.
  • Explain trends in networking that will affect the use of networks in small to medium-sized businesses.
  • Explain network security threats and its solutions.