Summary Computing Fundamentals

Summary: Computing Fundamentals
Network Models and Protocols

1. Network Models

1.1 Layered Network Models
 Network protocols are organized into layers, known as a 'protocol stack'.
 Each layer provides specific services to the layer above and uses the services of the
layer below.
 This structure allows abstraction, meaning upper layers don't need to know details
about how their data is routed through the network.

1.2 OSI/ISO 7-Layer Reference Model
 Developed by the International Standards Organization (ISO)
 Generic networking model
 Designed in the early 1980s
 Intended for multiple manufacturers and standards
 Originally focused on open systems and interfacing multiple stacks.
 Consists of seven layers, each serving a specific function.
 This model provides a standardized approach to communication across networks.
 Normally, 1 is at the base and 7 is at the top
 Layers:
o 1: Physical – Network hardware and electrical signals
o 2: Data Link – Error detection and packet framing
o 3: Network – Data addressing and delivery between networks
o 4: Transport – End-to-end messaging between applications
o 5: Session – Manages connection terms of a session
o 6: Presentation – Data presentation
o 7: Application – Network services for end-users and applications

 Please Do Not Throw Sausage Pizza Away

2. Network Devices
 Networking hardware
 Physical devices
 Allows hardware on a computer network to communicate and interact with one
another.

,2.1 Repeater
 Operates at the physical layer
 Amplifies signals to extend the transmission distance of signals across the network.
 Regenerates weakened signals and sends them further along.
 Copies bit by bit and regenerates it at its star topology connectors
 2-port device

2.2 Hub
 Multi-port repeater
 Connect multiple wires coming from different branches (fe: connector in star
topology which connect different stations)
 Collision domain of all hosts connected through Hub remains 1
 Doesn’t have the intelligence to find best path for data packets  inefficiencies and
wastage
 Broadcast incoming traffic on all ports, whereas bridges and switches only route
traffic towards their addressed destinations
 Operates at Layer 1

2.3 Bridge
 Operates at the data link layer
 filters traffic by reading the source and destination MAC (media access control)
addresses. This enables it to separate traffic between two LANs efficiently.
 Interconnecting two lans working on the same protocol
 Single input and single output port  2 port device
 Broadcast data to every node (like repeaters and hubs)
 Keeps MAC address up to date as soon as it discovers new segment  only desired
recipient receives subsequent transmission

2.4 Switch
 Multi-port bridge
 Buffer and design that can boost its efficiency(a large number of ports imply less
traffic) and performance
 Operates on the data link layer.
 Performs error checking before forwarding data
 Only sends valid packets to the correct port  divides collision domains of
connected hosts, improving efficiency.
 Broadcast domain remains the same

3. Types of Switches
 Unmanaged switches:
o Basic plug-and-play switches for small networks.
o Do not offer advanced configuration options
o Suitable for small networks or for use as an expansion to a larger network
 Managed switches:

, o Offer advanced features like VLANs, QoS, and link aggregation.
o Suitable for larger, more complex networks and allow for centralized
management
 Smart switches:
o Features similar to managed switches but easier to setup and manage
o suitable for small- to medium-sized networks.
 Layer 2 switches:
o Operate on the data link layer of the OSI
o Responsible for forwarding data between devices on the same network
segment
o suitable for traffic within the same segment.
 Layer 3 switches:
o Operate at the network layer
o Can route between different network segments
o More advanced than layer 2 switches
o Often used in larger, more complex networks
 PoE switches:
o Power over Ethernet capabilities
o supply power to network devices over the same cable that carries data.
 Gigabit switches:
o Support Gigabit Ethernet speeds
o Faster than traditional Ethernet speeds.
 Rack-mounted switches:
o Designed to be mounted in a server rack
o suitable for use in data centers or other large networks.
 Desktop switches:
o Designed for use on a desktop or in a small office
environment
o Typically smaller in size than rack-mounted switches.
 Modular switches:
o Modular design  easy expansion or customization.
o Suitable for large networks and data centers.



4. Routers, Gateways, Brouters and NIC

4.1 Routers
 Device like a switch that routes data packets based on their IP addresses.
 Mainly a Network Layer device.
 Connect LANs and WANs
 Have a dynamically updating routing table based on which they make decisions on
routing the data packets.

,  Divides the broadcast domains of hosts connected through it.




4.2 Gateway
 Passage to connect two networks that may work upon different networking models.
 Work as messenger agents that take data from one system, interpret it, and transfer
it to another system.
 Also called protocol converters and can operate at any network layer.
 More complex than switches or routers.




4.3 Brouter
 Bridging router
 Device that combines features of both bridge and router.
 Can work either at the data link layer or a network layer.
 Working as router capable of routing packets across networks
 Working as bridge capable of filtering local area network traffic

4.4 NIC
 Network interface card
 Network adapter
 Used to connect the computer to the network.
 Installed in the computer to establish a LAN.
 Has a unique id that is written on the chip
 Has a connector to connect the cable to it.
 The cable acts as an interface between the computer and the router or modem.