Network Tools and Devices

Network Tools and Devices

• A Network Interface Card (NIC) facilitates computer communication over a network.
• NICs use Media Access Control (MAC) addresses to distinguish computers.
• Repeaters are electronic devices used to amplify communication signals.
• Repeaters also filter noise from communication signals.
• A Hub is a connectivity device where network cables connect to form a network segment.
• Hubs retransmit incoming data packets or frames to all connected parts without filtering data.
• A Bridge connects network segments, directing information flow to specific destinations.
• A Switch forwards data, makes forwarding decisions, and filters data communication between ports.
• Switches filter traffic based on the MAC addresses in the packets of information.
• Routers forward packets between networks, processing the information within each packet.
• A Wireless Access Point (WAP) is a networking tool that enables wired networks to connect to wirelessly enabled devices.
• WAPs link wired network infrastructure consisting of routers, switches, and servers with wireless devices like laptops, smartphones, and tablets.
• Firewalls reject network access requests from unsafe sources while allowing requests from safe ones.
• A Patch Panel in a Local Area Network (LAN) is a mounted hardware assembly with ports that connect and manage incoming/outgoing LAN cables.
• A Krone Tool inserts wires into insulation-displacement connectors.
• Krone Tools utilize punch-down blocks, patch panels, keystone modules, and surface mount boxes.
• A Crimping Tool conjoins two pieces of metal by deformation.
• RJ45 (Register Jack 45) is an 8-pin/8-position plug or jack.
• RJ45s are commonly used to connect computers to Ethernet-based local area networks (LAN).
• A Wire Stripper cuts the outer sheath off of Ethernet and other LAN wires.
• Wire strippers are used to remove the outer insulation from LAN cables.
• A LAN Tester confirms and troubleshoots Ethernet network connections.
• LAN Testers are used by network experts and installers to ensure correct cable installation and operation.
• Keystone Jacks are modular connectors used to terminate twisted pair cables, typically Ethernet cables.
• Keystone Jacks are easy to install and repair, snapping into wall plates, patch panels, or surface-mount boxes.

Transmission Mediums

• The transmission medium is the physical path messages travel from sender to receiver.
• Transmission media include both cable media and wireless media.

Cable Media

• Cable media can be divided into twisted pair, coaxial, and fiber optic cable.
• Coaxial cable uses a single central conductor surrounded by a dielectric insulator.
• A conductive shield surrounds the dielectric, serving as the second conductor and protecting against interference.
• Twisted pair cabling is a wiring type where two conductors of a circuit are twisted together to improve electromagnetic compatibility.
• Twisted pair cables are classified by impedance, and whether they are shielded or unshielded.
• Unshielded Twisted Pair cabling has cable wires that are twisted together.
• Unshielded Twisted Pair cabling has relatively high noise and doesn't require grounding.
• Unshielded Twisted Pair cabling has slow data rates, is cheaper, and requires less maintenance.
• Shielded Twisted Pair cabling has twisted pair cables enclosed in foil.
• Shielded Twisted Pair cabling is less susceptible to noise and crosstalk and needs grounding.
• Shielded Twisted Pair cabling provides high data rates, and are moderately expensive.
• Fiber optic cable uses thin glass or plastic strands to send data via light.
• A bundle of optical fibers forms a fiber optic cable.
• Singlemode fiber carries light signals straight without bouncing.
• Light signals are transmitted without bouncing due to the tiny core
• Multimode fiber has a core that is 5-10 times greater in diameter than singlemode fiber.
• Multimode fiber can have multiple light signals flow through it at once.
• Signal distance is restricted due to its width.

Cable Types

• Straight Through Wired Cables are commonly used to connect a host to a client.
• Crossover Wired Cables are commonly used to connect similar devices.
• Rollover Cable is used to connect a computer terminal to a router's console port.
• Rollover cable is a type of null-modem cable

Computer Network Design Considerations

• Budget and cost are important factors to consider right at the start.
• Make a list of everything that needs to be purchased, what is already on hand, and the associated costs.
• Avoid compromising quality.
• Assess the physical location of computers to determine the most suitable locations.
• Account for near-future expansion in the network design, including estimating the number of systems potentially added in the next six months or year.
• Internet Service Provider is a major issue that needs consideration.
• Account for the number of users and a few extra who might access the network simultaneously to decide bandwidth and minimum requirements.
• Security is vital with a good security plan.
• A firewall is important and antivirus protection from threats and bugs is imperative.
• Consider both physical and logical security
• A backup system is vital to protect data.
• How often data needs to be backed up depends on the magnitude and frequency of data change.

Local Area Networks

• LAN networks connect computers over relatively small distances, like within a building.
• Converged Networks handle voice, video, and data.
• In converged networks, Layer 3 devices like routers have complete routing tables for efficient data sending.
• Switch networks complete single-path calculations.

Switch LAN Architecture

• A switched LAN architecture uses a hierarchical design ideal for small to medium businesses.
• Hierarchical network design divides a network into distinct layers.

Hierarchical Network Design

• The Access Layer interfaces with end devices (PCs, printers, IP phones).
• The access layer can include routers, switches, bridges, hubs, and wireless access points.
• The main purpose of the access layer is to provide a means of connecting devices to the network and controlling which devices are allowed to communicate on the network.
• The Distribution Layer aggregates data from access layer switches.
• The distribution layer enables broadcast domain delineation using virtual LANs (VLANs).
• The Distribution Layer transmits to the core layer for routing to a final destination.
• The Core Layer of the hierarchical design is the high-speed backbone, critical for interconnectivity between distribution layer devices.
• The core layer must be highly available and redundant to connect to Internet resources.
• The core aggregates traffic from all distribution layer devices, so it must have the capability of forwarding large amounts of data quickly.
• Borderless Switched Networks combine innovations and design considerations.
• Borderless Switched Networks are designed for organizations to allow anyone, anywhere, at any-time, and on any device securely.
• Hierarchical networks are well-suited for medium-sized businesses with user computers on one floor and server resources on another.
• Scalability in network design involves replicating design elements as the network grows.
• Expansion is easily planned and implemented because of the modularity of the design.
• Redundancy grows in importance as a network expands.
• Network administrators can increase availability through redundant hierarchical network implementations.
• Access layer switches can connect to two different distribution layer switches for path redundancy.
• Performance is enhanced by avoiding data transmission through low-performing, intermediary switches.
• Data is sent through aggregated switch port links from the access layer to the distribution layer at near wire speed in most cases.
• The distribution layer uses high-performance capabilities to forward traffic up to the core for final routing.
• Security is improved and easier to manage.
• Access layer switches can be configured with port security options.
• Manageability is simple on a hierarchical network since layers perform specific functions.
• Changes can be easily repeated without much configuration
• Maintainability is easier in hierarchical networks due to their modular nature and easy scalability. Switch functions are defined at each layer

Defining Networks with the OSI Model

• Standards are sets of rules that ensure the released hardware and software will work together.
• ISO (International Organization for Standardization) is a federation of standards organizations from multiple nations.
• ANSI (American National Standards Institute) coordinates and publishes computer and IT standards in the United States.
• IEEE (Institute of Electrical and Electronics Engineers) is a professional organization for the electrical and electronics field.
• In communication, established standards are called protocols.
• A framework aids in the design of hardware and software for communication.
• The ISO-OSI model serves this purpose and is superior to the TCP/IP model.

TCP/IP Model

• This model only has 4 layers in it
• Application Layer defines TCP/IP application protocols
• Examples include HTTP, Telnet, FTP, SMTP, DNS
• Transport Layer provides communication session management
• Examples include TCP, UDP, RTP
• Internet Layer packages and routes data
• Examples Include IP, ICMP, ARP, RARP
• Network Interface details how data is physically sent through the network
• Examples include Ethernet, Token Ring, Frame Relay

Comparing TCP/IP Model to OSI Model

• OSI Model: Application Layer, Presentation Layer, Session Layer, Transport Layer, Network Layer, Data Link Layer, Physical Layer
• TCP Model: Application Layer, Transport Layer, Internet Layer, Network Access Layer

Open Systems Interconnection (OSI)

• The OSI is used to understand and describe how different networking protocols and technologies interact within a networked system.
• OSI expresses the communication process into structured layers.
• OSI acts as a frame of reference in the design of communications and networking products.
• In the OSI model, Layer 7 (Application) enables users and applications to access network services.
• Layer 6 (Presentation) translates data into a common format.
• Layer 5 (Session) establishes a communication session between devices.
• Layer 4 (Transport) manages message fragmentation and reassembly.
• Layer 3 (Network) manages data routing and creates sub-networks.
• Layer 2 (Data Link) provides error-free transfer of data frames.
• Layer 1 (Physical) defines physical network media and signal methods.

OSI Model: Division of the Layers

• Layer 7, Layer 6, and Layer 5 are considered upper layers.
• Layer 4 is the middle layer.
• Layer 3, Layer 2, and Layer 1 are the lower layers.
• Layer 7, the Application Layer, performs duties for user application and providing application processes to access network services. HTTP, SMTP, and FTP are included.
• Layer 6, the Presentation Layer, is sometimes called the syntax layer. It serves as the data translator for the network. Presentation Layer concepts include character code conversion, data formatting, and data encryption.
• Layer 5 (Session Layer) establishes connection to identify session, negotiate services, send and transfer data, and re-establish services if disconnected. Also acknowledges the recipent of data.
• Layer 4, the Transport Layer, is the dividing line between the upper and lower layers of the OSI model, which sends and receives data utilizing TCP and UDP.
• Transmission Control Protocol (TCP) is connection-oriented and reliable. If a segment is dropped, the protocol detects it and resends the segment.
• User Datagram Protocol (UDP) is connectionless.
• UDP is for unreliable transport of segments. If dropped, the sender is unaware and there is no retransmission. Used for good Audio/Video Streaming.
• Layer 3, the Network Layer, handles switching, logical addressing and routing of packets, connection services, bandwidth, and multiplexing strategy.
  • Switching is the process to forward packets coming in from one port to a port leading towards the destination Connectionless switching forwards data without requiring a pre-established circuit whereas connection oriented switching requires a pre-established circuit.
  • Packet Switching divides data into packets whereas circuit switching has a dedicated communication link is established between two parties.
  • Message switching divides data into messages
• With routing , the router maintains a routing table to forward a packet based on the destination IP address.
• Unicast routing forwards unicasted traffic.
• Multicast routing sends traffic only to devices that wish to receive it.
• Broadcast routing has a host need to send messages to others
• Layer 2, the Data Link Layer is concerned with packaging data into frames and transmitting them. In addition, error detection/correction, and uniquely identifying network devices with MAC address is a function of this layer.
• Includes physical addressing, logical topology, Method of transmitting on the media
• Layer 1 is concerned with the physical properties of the network
• handles the transmission and electrical function of the network. Uses cabling, fiber optics. hubs and repeaters