Network Types and Components

Chapter 1: Network Types and Components

• Peer-to-Peer (P2P) networks allow computers to act as both clients and servers, directly sharing data resources.
• Local Area Networks (LAN) cover small geographical areas.
• Wide Area Networks (WAN) cover large geographical areas, linking multiple LANs.
• An Intranet is a private network exclusively for authorized users within an organization.
• An Extranet allows external users secure access to an organization's data.
• End devices include PCs, printers, and servers.
• Intermediary devices encompass routers, switches, firewalls, and wireless routers.
• Network media consist of copper cables (twisted pair, coaxial), fiber optic cables, and wireless transmission (Wi-Fi, Bluetooth).
• Copper cables are used for short to medium distances at a lower cost and include Ethernet cables like Cat5e and Cat6.
• Fiber optics are suitable for high-speed transmission over long distances and are resistant to electromagnetic interference, often used by internet service providers, offering long range, high bandwidth, immunity to EMI/RFI, and low signal dampening.

Electromagnetic Interference (EMI), Radio Frequency Interference (RFI) and Crosstalk

• EMI/RFI can distort signals due to radio and electrical sources, which can be resolved through shielding and grounding.
• Crosstalk, interference between nearby cables, can be minimized by twisting wire pairs to cancel electromagnetic fields.

Optic Fiber Cabling

• Single-mode fiber (SMF) is used for long-distance data transfer with low dispersion.
• Multimode fiber (MMF) is used for shorter distances with higher dispersion.
• MMF has a higher dispersion rate than SMF, restricting range to 500 meters.

Wireless Transmission

• Utilized for mobility (Wi-Fi, 4G/5G, Bluetooth) and applications like smartphones or IoT devices.

Network Topology

• Physical topology shows the physical placement of devices and cabling.
• Logical topology illustrates how devices are connected and addressed in the network.

Protocols, Security and Availability

• IP (Internet Protocol) governs addressing and routing on the internet.
• TCP/UDP are transport protocols ensuring reliable data transfer.
• Fault tolerance means the network continues to operate despite failures with redundant systems and alternative routes preventing downtime.
• Scalability enables the network to grow without substantial costs or impacting existing systems
• Quality of Service (QoS) prioritizes network traffic based on need.
• Security measures protect data and devices from external and internal threats.
• Security measures include firewalls, VPNs, intrusion prevention systems (IPS), antivirus software, and access control lists (ACL).

Cloud Solutions

• Public cloud offers shared infrastructure and is cost-effective and scalable, available to all.
• Private cloud is dedicated to a single organization for enhanced control and security.
• Hybrid Cloud combines public and private clouds for increased flexibility and optimization.
• Community cloud is shared among organizations with similar requirements offering cost savings and security.

Internet connection types

• Cable offers high bandwidth and availability using the same cable as cable TV.
• DSL, using telephone lines, provides high bandwidth with faster download speeds than upload speeds (ADSL).
• Mobile (Cellular) offers internet access through mobile networks, limited by phone and tower capacity.
• Satellite provides internet access to remote areas requiring a clear view of the satellite.
• Dial-Up is inexpensive but slow internet access using telephone lines, suitable for mobile access during travel.

Chapter 3: Protocols and Delivery Options

• Protocols - Agreed upon rules for communication between devices like HTTP, TCP/IP, and Ethernet.
• Unicast is a one-to-one delivery from a web browser to a web server.
• Multicast is a one-to-many delivery method used in video streaming.
• Broadcast is a one-to-all delivery, for example, ARP requests.
• PDU (Protocol Data Unit) defines a data packet at each layer of the protocol stack (segment, packet, frame).
• Encapsulation/De-encapsulation: Adding or removing headers and trailers as data moves through the protocol stack.
• Application Layer protocols include HTTP, DNS, DHCP, and SMTP.
• Transport Layer protocols include TCP (segment) and UDP (datagram).
• Internet Layer protocols include IPv4/IPv6, ICMP, and OSPF.
• Network Access Layer protocols include Ethernet (frame) Wi-Fi and ARP.

Encapsulation

• Application Layer: Data with no additional information (e.g., HTTP request).
• Transport Layer: Segment/datagram with TCP/UDP header (source/destination ports, sequence number, ACK).
• Network Layer: Packet with IP header (source/destination IP, TTL).
• Datalink Layer: Frame with MAC header + trailer (source/destination MAC, CRC).
• Physical Layer: Bits converted to electrical, optical, or radio signals.

De-encapsulation

• Physical Layer: Receives bits and reconstructs the frame, for example, Ethernet cable converts electrical signals to binary data.
• Datalink Layer: Removes MAC header, checks CRC for errors, and switch uses MAC addresses for forwarding.
• Network Layer: Checks IP address, determines forwarding (route or local), & routers use IP tables for decisions.
• Transport Layer: TCP reconstructs data stream using sequence numbers and UDP delivers datagram directly to application.
• Application Layer: Processes raw data, for example, HTTP response to browser.

Addressing in Networks

• Segmenting increases efficiency by dividing large messages into smaller parts.
• Multiplexing enables multiple communications to share the same network connection.
• Standards (TCP/IP) ensure different devices can communicate.
• Routers use IP addresses to forward packets between networks.
• Switchers use MAC addresses to send frames within a network.

SSH vs Telnet

• SSH is encrypted (port 22) and provides secure remote access.
• Telnet is unencrypted (port 23) and insecure.

Switching and MAC Addresses

• MAC table: The switch learns which port a MAC address belongs to.
• Flooding is when the switch sends the frame out all ports except the incoming port if an unknown MAC address is used. The frame is sent through the gateway (router's MAC).
• Aging time: MAC address entries are deleted due to inactivity often set for 300 seconds.

The role of the physical layer

• Handlesthe translation of raw data into electrical signals, light pulses, or radio waves, allowing data to move physically across a network.

Principal Tasks performed by the Physical Layer

• Transmitting binary bits (as electrical signals through copper, light through fiber, or radio waves through wireless).
• Defining transmission media (cable or wireless)
• Encoding data
• Signaling

Physical Network Cards

• Network Interface Cards (NICs) connect devices to the network.
• Ethernet NICs are utilized to make wired connections.
• Wireless LAN (WLAN) NICs are utilized to make wirless connections

Compnents of physical connection

• Includes signal transmission, representing data using electrical signals, light pulses, or radio waves.
• Included also is hardware, which includes network interface cards, interfaces, contacts, and cables

Copper Cabling Issues

• EMI/RFI refers to electromagnetic interference which manifests as elextromagentic noise
• Crosstalk occurs when signal leak from nearby cables
• This can be mitigated by implementing proper shielding, using sheilded twisted pair cables in addition to the correct cabling techniques

Unshielded Twisted Pair Specification

• Consists of four pairs of color-coded copper wires twisted together
• Often utilized to connect to a local area network due to its compact size and relative ease of istallation
• RJ-45 is utilized to create standards
• signal loss occurs with improper implimentation

Cable Specifications

• Utilize Ethernet Straight Through to connect a client to either a router or switch
• Utilize Ethernet Crossover to connect similar hardware for example a router to a router, or a switch to a switch
• Rollover cables are proprietory to Cisco for console ports

Encoding and Signaling

• Encoding Transforms data bits into distinct signals recognizable by both ends.
• Transmission and voltage indicates 0: High to low voltage shift 1: Low to high voltage shift 1: is a long pulse 0 is a short pulse Mid way through every bit is transition

Network Performance

• Bandwith: Capacity of data transmitted through a communications medium. Bps(bits per second) is the measurement of this medium
• Elements Influencing this quality are the media and signaling attributes
• Latency: Delay experienced due to the movement of data from one source to another through a network.
• Throughput: Quantitative measurement of data actually transmitted over a link, can be restricted by traffic conditions or network
• Goodput - Effective data transmitted over a line, throughput is the measure once overhead is removed goodput>throughout>bandwith