PC Networking: LAN, MAN, and WAN

• PC networking involves two or more connected computers sharing resources like data, printers, or internet connections.

Network Types

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

Local Area Networks (LAN)

• LANs consist of computers, network interface cards, peripherals, networking media, and network devices.
• They enable local file and printer sharing, and internal communication, such as email for businesses.
• LANs tie together data, local communications, and computing equipment.
• LANs operate within a limited geographic area.
• LANs allow high-bandwidth media access to many users.
• LANs provide full-time connectivity to local services.
• LANs connect physically adjacent devices.
• Common LAN technologies include Ethernet, Token Ring, and FDDI.

Metropolitan Area Networks (MAN)

• A MAN spans a metropolitan area like a city or suburban region.
• MANs connect LANs separated by distance but located within a common geographic area.
• MANs interconnect users in a larger geographic area than a LAN but smaller than a WAN.
• MANs connect networks within a city into a single, larger network.

Wide Area Networks (WAN)

• WANs interconnect LANs, providing access to computers or file servers in other locations.
• WANs connect user networks over a large geographic area, enabling business communication across great distances.
• WANs facilitate telecommuting, allowing people to work from home.
• WANs operate over large, geographically separated areas.
• WANs allow users to engage in real-time communication with others.
• WANs provide full-time remote resources connected to local services.
• WANs offer email, WWW, file transfer, and e-commerce services.
• Common WAN technologies include modems, ISDN, and DSL.

Digital Bandwidth

• LANs and WANs use the term bandwidth to describe their capabilities.
• Bandwidth is the amount of information that can flow through a network connection in a given period of time.

Networking Importance

• A computer network connects PCs and other devices for communication and resource sharing.
• Networks vary in size, from single offices to spanning the globe.
• Common network technologies include Ethernet and Fast Ethernet.
• Ethernet operates at 10 Mbps, while Fast Ethernet operates at 100 Mbps.

Network Operations

• Devices communicate by transmitting information in packets.
• Packets contain source and destination addresses.
• Network equipment uses address information to route packets.
• Ethernet and Fast Ethernet networks use CSMA/CD protocol.
• CSMA/CD allows only one device to communicate at a time.
• Collisions are detected, and devices stop transmitting and retry.

Benefits of Networking

• Networking enables the sharing of expensive peripherals like printers.
• Networking facilitates data transfer without floppy disks.
• Networking centralizes key computer programs.
• Networking automates backups of critical files.
• A network facilitates efficient communication through e-mail, instant messaging, chat rooms, and video conferencing.
• Networking allows sharing of hardware; multiple computers can access a shared laser printer on the network.
• Authorized users can access data and information stored on other computers within the network in a networked environment.
• Users connected to a network can access application programs.

Network Components

• A small network typically includes PCs and peripherals, network cables, a hub, and a network operating system.
• Network interface cards (NICs) may be required for PCs to connect to the network.

Network Topology

• Network topology is the arrangement of elements in a computer network.
• Physical topology refers to the placement of components and cable installation.
• Logical topology shows how data flows within the network.

Bus Topology

• The bus topology is typically utilized when a network installation is small, straightforward, or temporary.
• In a bus network, a single cable connects all computers.
• Only one computer can send a message at a time.
• The bus topology is simple, reliable for small networks, easy to use, and understand.
• Bus topology requires the least amount of cable.
• A bus is easy to extend by joining cables with a barrel connector.
• Heavy network traffic can slow a bus considerably.
• Computers don't coordinate transmission times, leading to interruptions.
• Barrel connectors weaken the electrical signal.
• Troubleshooting can be difficult and cable breaks can halt the entire network.

Star Topology

• In the star topology, cables run from computers to a central hub.
• Each computer communicates with the central hub.
• The hub can be active or passive.
• It is easy to modify and add new computers to a star network without disrupting the rest of the network.
• The center of a star network is suitable to diagnose network faults.
• Intelligent hubs can offer centralized monitoring and managment of the network.
• Single computer failures do not disrupt the entire network.
• Several cable types can be used in the same network with a hub.
• If the central hub fails, the whole network will stop operating.
• Star newtorks often require a device at the central point to broadcast or switch network traffic.
• It costs more to cable a star network due to all cables going to a central point.

Ring Topology

• In a ring topology, each computer is connected to the next, forming a circle.
• Each computer retransmits what is received from the prior one.
• Messages flow around the ring in one direction.
• Some ring networks use token passing.
• With token passing, a short message is passed until a computer wishes to send data.
• Equal access to the token prevents monopolization.
• Fair sharing allows graceful degradation as users are added.
• Failure of one computer can affect the whole network.
• Troubleshooting and modifying ring networks can be difficult.

Mesh Topology

• The mesh topology is distinguished by having redundant links between devices.
• A true mesh has a link between each device, making it unmanageable.
• Data can be transmitted from different devices simultaneously.
• Mesh topology can withstand high traffic.
• Alternative routes are available in case of component failure.
• Expansion can be done without disrupting other nodes.
• Mesh networks have high chances of redundancy.
• Overall cost and maintenance are very high.

Open Systems Interconnect (OSI) Reference Model

• The OSI model helps to understand network communication by breaking it into layers.
• It aids in designing, building, and maintaining networks.
• The concept involves analyzing the flow of data and the rules governing the flow.
• The OSI model ensures compatibility and interoperability between different network technologies.
• It is the primary model for network communication guidelines.
• The OSI model defines network functions at each layer.
• The framework facilitates an understanding of information travel throughout a network.
• The OSI reference model has seven numbered layers.

OSI Layers

• Layer 7: Application layer provides network services to user applications, such as email or file transfer by synchronizing and establishing agreements between communication partners.
• Layer 6: Presentation layer ensures data readability between different systems by handling encryption, data conversion (e.g., ASCII to EBCDIC), and graphic/sound standards (e.g., JPEG, MIDI).
• Layer 5: Session layer establishes, manages, and terminates sessions between two communicating hosts; it manages data exchange.
• Layer 4: Transport layer segments data from a sending host and reassembles it as a data stream on the receiving host ensuring delivery of the message.
• Layer 3: Network layer provides connectivity and path selection between two host systems that might be located on geographically separated networks; it concerns logical addressing.
• Layer 2: Data Link layer provides reliable transit of data across a physical link; it manages physical addressing, network topology, and error notification.
• Layer 1: Physical layer defines electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link between end systems like voltage levels, timing changes, physical data rate, cabling and maximum transmission Distance.
• Layering breaks down network communication, standardizes components, allows different hardware and software to communicate, and isolated changes for quicker development.

Networking Devices

• Networking devices directly connect to a network segment and have two types: End user and Network devices.
• End user devices include computers, printers, and scanners.
• Network devices connect end-user devices and allow them to communicate.

Repeaters

• Repeaters exist at Layer1 of the OSI model and regenerate/retime network signals (electrical or light).
• Repeaters are classified as Layer 1 devices because they only act on the bit level.

Hubs

• A hub regenerates and retimes network signals.
• Hubs are common connection points for devices in a LAN and contains multiple ports.
• It copied to the other ports so that all the LAN's segments can see all the packets.
• Hubs amplify and propagate signals through the network.
• Hubs do not require filtering, path determination or switching.
• Hubs are used as network-concentration points.

Network Interface Cards (NICs)

• NICs are Layer 2 devices, because each has a Media Access Control (MAC) address.
• This address controls data communication for the host on the LAN.

Bridges

• Layer 2 devices create LAN segments, each of which is a separate collision domain.
• Bridges filter traffic on a LAN by directing it to local traffic.
• Bridges keep track of which MAC addresses are on each side and make forwarding decisions based on the list.
• They filter network traffic by looking only at the MAC address.
• They can analyze incoming frames and forward (or drop) them based on addressing information.
• Bridges collect and pass pockets between two or more LAN segments.
• More collision domains are created by Bridges, allowing more than one device to transmit simultaneously.
• They maintain MAC address tables.

Switches

• Switches connect LAN segments.
• Switches use a table of MAC addresses.
• Fast data link layer devices that let multiple physical LAN segments interconnect in single larger networks.
• Micro segmentation allows segments on the switch to be private.

Routers

• Routers are internetworking devices that pass packets between networks.
• Routers are based on Layer 3 addresses.
• They make decisions on the best path for delivery of data on the network.
• Routers can make decisions using network addresses not Layer 2 MAC addresses.
• The purpose of a router is to examine incoming packets (Layer 3 data), choose the best path for them through the network, and then switch them to the proper outgoing port.
• Routers are the most important traffic-regulating devices on large networks.

Patch Panels

• Patch panels are convenient groupings of RJ-45 jacks with 12, 24, and 48 ports, and are typically rack-mounted.
• They provide connectivity or conducting paths, and classified as Layer 1 devices.

Workgroups

• A workgroup is Microsoft's designation for a peer-to-peer computer network.
• Microsoft operating systems in the same workgroup may allow access to files, printers, or Internet connection.

TCP/IP

• TCP/IP is the basic communication language or protocol of the Internet.
• TCP/IP can also be used as a communications protocol in a private network.
• TCP manages the assembling of a message or file into smaller packets.
• IP handles the address part of each packet.
• The client/server model of communication is what TCP/IP uses.
• TCP/IP communication is primarily point-to-point.

Network Addressing

• The IP address is a 32-bit number that is entered into a NIC's configuration parameters.
• The IP address is used for connections of multiple networks and when accessing the Internet.
• The IP address is shown using dotted decimal notation.
• Class A addresses have any number from 1 to 126 as the first number.
• Class B addresses have any number from 128 to 191 as the first number.
• Class C addresses have numbers 192 through 223.

IP Address Breakdown

• An IP address is broken into two major parts-the network number and the host number.
• All computers on the same network have the same network number.
• All computers on the same network have unique host numbers.
• A business has two networks connected together with a router.
• On each network, there are computer work-stations and printers.
• Each of the networks must have a unique network number.
• Network device cannot be assigned the IP addresses 193.14.150.255 or 193.14.151.255 because these numbers represent the broad cast address used with each network.

IP Address Class

• Number of bits that are used to represent the network number and the host number depends on which class of IP addresses being used.
• Class A IP addresses, the first eight bits (the first number) represent the network portion and the remaining 24 bits (the last three numbers) represent the host number. Class B IP addresses, the first 16 bits (the first two numbers) represent the network portion and the remaining 16 bits (the last two numbers) represent the host number.
• Class C IP addresses, the first 24 bits (the first three numbers) represent the network portion, and the remaining eight bits (the last number) represent the host number

Subnet Mask

• The subnet mask is a number that the computer uses to determine which part of the IP address represents the network.
• The subnet mask for a Class A IP address is 255.0.0.0.
• The subnet mask for a Class B IP address is 255.255.0.0.
• The subnet mask for a Class C IP address is 255.255.255.0.0.
• Class A address 0 & 127 is reserved for loopback and primarily is a means of testing the transmission of the local computer.

Peer-to-Peer (P2P) Networking

• Resources are shared directly between participants without central coordination.
• Peers act as both suppliers and consumers of resources.

Crimping Tool

• The crimping tool can be used to punch RJ45 and telephone cables.
• Insert the connector in the crimping tool such that the golden lines can face the black edges.

Data Cable Tester

• Tests RJ45 and RJ11 network cables.
• Tests correspondingly double-twisted cables 1, 2, 3, 4, 5, 6, 7, 8 and Ground.
• Puts cables into both main tester and remote tester.

Network Cable Types

• Unshielded Twisted Pair (UTP):
• Relies solely on the cancellation effect produced by the twisted wire pairs, to limit signal degradation caused by EMI- electromagnetic interference and RFI- radio frequency interference.
• Shielded Twisted Pair (STP):
• Combines the techniques of shielding, cancellation, and twisting of wires by wrapping Each pair of wires in metallic foil.
• Screened Twisted Pair (ScTP):
• Also known as Foil Twisted Pair (FTP), SCTP is essentially UTP wrapped in a metallic foil shield.
• Fiber-optic Cable:
• Capable of conducting modulated light transmissions.

RJ-45 Connector

• The standard 10BASE-T termination is the registered jack-45 connector (RJ-45).
• RJ-45 connector reduces noise, reflection, and mechanical stability.

Network Cables

• Straight-Through Cable:
  • Used to connect a computer to a hub or switch.
• Crossover Cable:
  • Used in a peer-to-peer fashion.

Ethernet Cable Tips:

• A straight-thru cable has identical ends.
• A crossover cable has different ends.
• A crossover has one end with the orange set of wires switched with the green set.
• No more than 1/2" of the Ethernet cable should be untwisted otherwise it will be susceptible to crosstalk.