Network Fundamentals

Exploring the Network

• The Internet enables individuals to create and globally access information.
• Data networks support remote work, reduce travel costs/time, and make training more affordable.
• Networks enhance hobbies/interests through global communities.

Technology Then and Now

• Communication methods include texting, social media, collaboration tools, blogs, wikis and podcasting

Networks of Many Sizes

• Small Home Networks (SHN) connect a few computers with the Internet.
• Small Office/Home Office (SOHO) allows computers in home/remote offices to connect to corporate networks.
• Medium to Large Networks (MN-LN) link locations with hundreds/thousands of interconnected computers.
• World Wide Networks (WWN) connect hundreds of millions of worldwide computers, like the Internet.
• A host/end device refers to every computer connected to a network
• Servers provide information to end devices. Examples: email, web, file servers
• Clients are computers requesting information from servers.
• Client and server software commonly run on separate computers
• Peer-to-peer networks involve a client functioning as the server, common in small businesses/homes.
• Peer-to-peer networks are easy to set up, less complex/costly, but lack centralized administration, security, scalability, and may have slower performance.
• IBM defines networking as two or more computers connected by wired/Wi-Fi for transmitting, exchanging, or sharing data and resources.
• Network infrastructure categories include: devices, media and services
• An end device is where a message originates or is received.
• Data originates with an end device, flows through the network, and arrives at an end device

Intermediary Network Devices

• An intermediary device interconnects end devices in a network, like switches, wireless access points, routers and firewalls
• Intermediary devices manage data flow by regenerating, retransmitting, maintaining pathway information, and notifying errors.
• Communication across a network uses a medium to allow a message to travel from source to destination
• Networks use metallic wires (copper), glass(fiber optic cables), or wireless transmission
• Network diagrams (topology diagrams) use symbols to represent devices
• Key terms to remember are Network Interface Card (NIC), physical port, and interface.

Types of Networks

• Local Area Network (LAN) spans a small geographic area, owned/operated by an individual or IT department.
• Wide Area Network (WAN) spans a large area, typically involving a telecommunications service provider.
• Other network types: Metropolitan Area Network (MAN), Wireless LAN (WLAN), Storage Area Network (SAN).
• LAN characteristics: small area (home, school), administered by a single entity, and provides high-speed bandwidth.
• WAN characteristics: interconnects LANs over wide areas, administered by multiple providers, and offers slower links between LANs.
• The Internet consists of interconnected LANs and WANs using copper wires, fiber optic cables, and wireless transmissions.
• No single entity owns the Internet, but organizations like IETF, ICANN, and IAB help maintain its structure.
• Intranet is a private LAN/WAN collection internal to an organization, accessible only to authorized users.
• Extranets offer secure network access to external individuals working for a different organization

Internet Access Technologies

• Options for home/small offices: broadband cable, DSL, wireless WANs, and mobile services.
• Organizations need faster connections to support IP phones, video conferencing, and data center storage
• Business-class interconnections: business DSL, leased lines, and Metro Ethernet.
• Ethernet WAN extends LAN access to the WAN
• Business DSL has variations like Symmetric Digital Subscriber Lines (SDSL).
• Satellite connections are available where wired solutions don't exist.

Home and Small Office Internet Connections

• Cable provides high bandwidth and is always on, offered by cable television providers.
• DSL also provides high bandwidth, always on, runs via telephone lines.
• Cellular connections use cell phone networks, available where there is a signal.
• Satellite is a major benefit to rural areas lacking Internet Service Providers.
• Dial-up uses a modem and is an inexpensive, low bandwidth option.

Business Internet Connections

• Corporations require managed, dedicated and higher bandwidth connections

Traditional Separate Networks

• Schools once used separate cabling for data, telephone, and video networks with different technologies and standards

Converged Networks

• Converged networks carry multiple services (data/voice/video) over a single link
• Converged networks, unlike dedicated ones, can deliver data, voice, and video between different types of devices over the same infrastructure using the same rules/ standards

Network Architecture

• Network architecture refers to technologies supporting the infrastructure that moves data across the network.
• It should meet user expectations with: fault tolerance, scalability, QoS, and security.

Fault Tolerance

• Fault tolerant networks limit the impact of failures by limiting the number of affected devices
• Multiple paths are required for fault tolerance.
• Reliable networks use packet switching for redundancy
• Packet switching divides traffic into packets routed over a network
• Each packet can take a different path to the destination
• Circuit-switched networks can not do this as they are which establish dedicated connections

Scalability

• Scalable networks expand quickly to support new users/applications without service impact.
• Scalable networks are made according to accepted standards and protocols

Quality of Service

• Voice and live video need reliable delivery, which is prevented when bandwidth is low and QoS isn't configured.
• Quality of Service (QoS) helps reliably deliver content
• With a QoS policy, routers can manage data/voice traffic flow easier.

Security

• Key areas to address: infrastructure and information security
• Physical security involves protecting network devices, preventing unauthorized software access and information/data transmitted

Network Security Goals

• Confidentiality: ensuring only intended recipients can read the data
• Integrity: assurance that the data has not been altered with during transmission
• Availability: providing timely/reliable data access to authorized users.

New Trends

• Networks must adjust to accommodate new technologies and user devices that effect organizations and consumers
• Emerging trends include "Bring Your Own Device" (BYOD), online collaboration, video communications, and cloud computing.
• BYOD is when users use their own devices and allows opportunities and flexibility.
• BYOD allows users personal tools to access information and communicate
• Devices include: laptops, netbooks, tablets, smartphones, and e-readers.
• Online collaboration lets users work together on joint projects.
• Collaboration tools like Cisco WebEx connect users for instant communication, interaction, and goal achievement.
• Collaboration is a high priority for businesses and education.
• Cisco TelePresence powers face-to-face meetings, enabling productive anywhere
• Organizations are transforming their customer experiences.

Cloud Computing

• Cloud computing lets users store files/backups on remote servers
• Apps such as word processors and photo editors are accessible using the Cloud
• Cloud computing extends business capabilities on demand from any device
• Data centers that are smaller companies that can't afford their own data centers, lease server and storage services from larger Cloud organizations

Four Types of Clouds

• Public Clouds: apps/services available to the general public, pay-per-use or free;
• Private Clouds: apps/services for specific organizations like the government
• Hybrid Clouds: mix of two or more cloud types(custom and public)
• Custom Clouds: unique architectures

Technology Trends in the Home

• Smart homes integrate technology into appliances for interconnectivity.
• Ovens can communicate with calendars to schedule cooking.

Powerline Networking

• Powerline networking connects devices to a LAN without network cables or wireless, through electrical outlets.
• Standard powerline adapters enable LAN connections via electrical outlets.
• Wireless broadband (besides DSL/cable) connects homes/small businesses.
• Wireless Internet Service Providers (WISPs) connect subscribers to designated access points/hotspots, in rural areas

Security Threats

• Internal threats are show to cause the most security breaches and BYOD strategies make corporate data more vulnerable.
• Robust security employs multiple layers of defence

Network Security Components

• Include antivirus/antispyware on devices, and firewall filtering to block unauthorized access
• Larger networks need dedicated firewalls, Access Control Lists (ACLs), Intrusion Prevention Systems (IPS),and Virtual Private Networks (VPNs) for secure remote access.

Cisco Network Architecture

• Networks require a standard architecture to efficiently connect people, devices, and information.
• Network architecture involves integrated devices, connections, and products for supporting the technologies and applications Routers and switches are the foundation of all network architectures
• CCENT and CCNA certifications: Cisco Certified Network and Routing and Switching Certification Associate to pass two exams, includes Cisco Certified Entry Network Technician (CCENT), and the Second exam focuses on IPv4 and IPv6 routing and WAN technologies as well as LAN switching and infrastructure services/maintenance

Communication Fundamentals

• Communication requires a source, destination, and a channel
• Rules/protocols govern all methods

Rules Establishment

• Effective communication protocols use: identified sender/receiver, language, delivery speed/timing, and confirmation/acknowledgment requirements
• Protocols define message encoding, delivery, formatting, encapsulation, timing and size.

Message Encoding

• Encoding between hosts must be in format for the medium
• Messages are converted to bits by the sending host-Bits are encoded into sound, light or electrical patterns based on the network medium.
• The destination hosts then receives and decodes the data

Message Formatting and Encapsulation

• There is set format for data and addressing
• Data is encapsulated.
• Computer messages are framed before transmitting-Frames provide addresses for source and destination.

Message Size

• Messages are broken into sized sentences
• Broken down pieces travel through the network
• Each is sent separately
• Each frame has unique addressing

Message Timing

• Access Method-Hosts need to know when to start sending data for proper data delivery to avoid collisions
• Flow Control balances source and host speeds
• Response Timeout-Hosts use rules for action taken when response time has been exceeded and what action to take.

Protocol Suites

• Protocol suites such as TCP/IP provides comprehensive service
• Protocols provide specifications or develop vendors
• The TCP/IP protocols are standard that available to vendors to implement.
• The Internet came out of ARPANET which was founded by U.S. Department of defence for use by universities and research

Communication Process

• Web servers prep HTML pages for HTTP transfer
• Data is broken down into TCP segments
• The TCP/IP is encapsulated with source and destination IP
• Ethernet is encapsulated with source and destination addresses

Open Communication

• Standard that promote innovation
• Vendor Neutral Standards
• Standard development to promote innovation

Internet Standards

• Internet Society(ISOC) promotes open development

Internet Architecture Board

• IAB-Management and Development for ISOC Standards

Internet Engineering Task Force

• Maintains Internet and TCP/IP technologies

Internet Research Task Force (IRTF)

• focused on long-term research

Internet Cooperation Numbering-ICANN-coordination for IP and Addresses

Electronics and Communications

• IEEE-Dedicated to advance technological innovation

Electronic Industries -Alliances EIA-Standard for Eletrical Wiring

Telecommunications Industry-Voice over IP devices and Satellite

The Benefits of Using a Layered Model

Helps assist to organize and design better protocols Provides support and competitions and different vendor Prevent technology changes from affecting other layers Provides a common language for networking

OSI Reference Model

• Contains protocols used for Process-to-process Provide common representation of data Provide Session Transmitting data Provide exchanging of data Physical connectivity of devices Also called OSI model Provide framework for model TCP/IP model Consist of Networking Protocols