Computer Science - Networking Notes

This is genuinely just human bio please kill me now.

DOD TCP/IP model - purposes

• Standardisation of Network Communication

• Reliable Data Transmission

• Routing and Adressing

• Support for a wide range of Services

• Scalability and Flexability

• Foundation for modern internet

DOP TCP/IP model - Standardisation of Network Communication

Provides a standardised set of protocols for transmitting data over networks. Ensures that different computer systems, regardless of their hardware and software configurations can communicate effectively.

DOP TCP/IP model - Reliable Data Transmission

Splits data into packets, transmitting them and then reassembling them at the destination, while also handling error checking and correction.

DOP TCP/IP model - Routing and Addressing

The IP component is responsible for addressing and routing packets to their destination across multiple networks. This is crucial for large-scale networks where the data must traverse various types of networks and devices.

DOP TCP/IP model - Support for a wide range of services

Many types of services and applications from file transfers and email to complex systems for command and control.

DOP TCP/IP model - Scalability and flexibility

Designed to scalable and adaptable to a range to network architectures, from small local networks to global communities.

DOP TCP/IP model - Foundation for the modern internet

Laid the groundwork for the modern Internet, using these protocols universally for all forms of digital communications.

Different types of layers in the DOD TCP/IP model

• Application

• Transport

• Internet

• Network

DOD TCP/IP model - Application Layer

Role and Functions

• Interfaces with user applications, enabling functionalities such as email, file transfers and web browsing.

Key protocols

• SMTP, FTP, HTTP, HTTPS, DCHP, DNS

Devices Required

• Servers and PC’s

DOD TCP/IP model - Transport Layer

Role and Functions

• Manages end-to-end communication, ensuring reliable data transfer for TCP (transition control protocol) and connectionless communication for UDP. Segments and manages data flow.

Key protocols

• TCP, UDP

DOD TCP/IP model - Internet Layer

Role and Functions:

• Handles logical addressing, routing, packet fragmentation and reassembly. Determines optimal packet routing paths.

Key Protocols:

• IPv4, IPv6, ARP, ICMP

Devices:

• Routers

DOD TCP/IP model - Network Layer

Role and Functions:

• Deals with physical and data link issues. Includes bit transmission, frame synchronisation, error handling and MAC addressing.

OSI Model - Physical Layer

Function:

• Handles the physical connection between devices, including bit synchronisation, transmission rate, physical topologies and transmission rates.

Protocols:

• Ethernet cables and fiber optics

Devices:

• Hubs, Repeaters, Modems, Cables, Network adapters

OSI Model - Data Link Layer

Functions:

• Defines the format of data on the network. Provides error detection and correction to ensure packets are free from errors.

Protocols:

• Ethernet (802.3), Wi-fi (802.11)PPP, Frame Relay

Devices:

• Bridges, Network Interface Cards (NICs), Switches, Wireless access points

OSI Model - Network Layer

Function:

• Determines how data is sent to the receiving devices and which route to take. Handles logical addressing, routing and traffic control.

Protocols:

• IP, ARP, RARP, ICMP

Devices:

• Routers, Layer 3 switches, Firewalls

OSI Model - Transport Layer

Functions:

• Manages end-to-end communication, ensuring reliable data transfer for TCP and connectionless communication for UDP. Segments and manages data flow.

Protocols:

• TCP, UDP

Devices:

• Firewalls and Load balancers

OSI Model - Session Layer

Functions:

• Manages sessions between applications. Handles setup, coordination (updating data between different systems/platforms) and termination of conversations between applications.

Protocols:

• netBIOS and RPC

Devices:

• Gateways/Firewalls

OSI Model - Presentation Layer

Function:

• Transforms data to provide a standard interface for the application layer. Handles encryption, compression and translation between data formats.

Protocols:

• SSL, TLS, MIME

Devices:

• Gateways

OSI Model - Application Layer

Function:

• Interacts with end-user software applications (Users interacting with intended software)

Protocols:

• HTTP, FTP, SMTP, Telnet

Devices:

• Gateways, Proxy Servers

Mnemonic for remembering OSI layers

1 → 7: Please Do Not Throw Sausage Pizza Away

Mnemonic for remembering DoD TCP/IP models

1 → 4: Missing In The Action

What is this?

A wired router

What is this?

A wireless router

What is this?

A switch

What is this?

A W.A.P (Wireless access point)

What is this?

A firewall

What is this?

The internet

What is this?

A server

What is a UTP (Unshielded Twisted Pair)?

TCP/IP Layer:

• Network Layer

Function:

• Used for connection network devices and transmitting data with less interference. It is a type of copper cable used in many ethernet networks. It consists of wires twisted together to reduce electromagnetic interference.

Technical Details:

• Categories: Cat 5e, Cat 6, Cat 6a, Cat 7 (each supporting increasing data rates and bandwidth). Typical use in LAN environment

What is a Fiber Optics?

TCP/IP Layer:

• Network Layer

Function:

• Transmits data as light pulses, ideal for long distances and high data rates. It is immune to electromagnetic interference.

Technical Details:

• Types: Single-mode (long distances and high bandwidth) and multimode (short distances and less bandwidth).

• Standards: OS1, OS2 (single mode); OM1, OM2, OM3, OM4, OM5 (multiple modes)

What is the meaning of Wireless as a network component?

TCP/IP Layer:

• Network Layer

Function:

• Uses electromagnetic waves to transmit data, allowing for mobile connections and infrastructure flexibility. It includes radio signals/infrared signals to transmit data across air and no physical wires.

Technical Details:

• Frequencies: 2.4 GHz (wider coverage, slower speed), 5 GHz (faster speed, shorter range).

• Standards: IEEE 802.11a/b/g/n/ac/ax

What is a Router?

TCP/IP Layer:

• Internet Layer

Function:

• Directs data packets between networks based on IP addresses, managic traffic within interconnected networks. It examines the destination IP address of a pocket and determines the best route for it and forwards it accordingly.

Technical Details:

• Routing Protocols: OSPF, BGP, EIGRP. Capable of layer 3 switching, QOS, IPv4 and IPv6 support.

What is a Switch?

TCP/IP Layer:

• Network Layer

Function:

• Connects devices on the same network segment, using MAC addresses to send data packets directly to devices, reducing unnecessary traffic. It is used to connect devices within the same network segment. A switch can identify which device the data needs to be sent to using MAC addresses.

Technical Details:

• Types: Managed (configurable options), unmanaged (plug and play), PoE (Power over Ethernet).

• Standards: IEEE 802.3 (Ethernet), IEEE 802.1D (STP), IEEE 802.1Q (VLAN)

What is a Wireless Access Point (WAP)?

TCP/IP Layer:

• Network Layer

Function:

• Connects wireless clients to a wired network, extending user mobility and network availability. It bridges the gap between a wired network and wireless clients.

Technical Details:

• Modes: Bridge, Repeater, Client mode. Supports security standards like WEP, WPA, WPA2.

What is a Firewall?

TCP/IP Layer:

• Internet Layer

Function:

• Monitors and controls incoming and outgoing network traffic based on security rules, blocking unauthorised access. It can operate at multiple layers and essentially provides a barrier between a secure internal network and the internet.

Technical Details:

• Types: Hardware (stand-alone unit), software (program on computer), UTM (Unified Threat Management).

• Features: Packet filtering, stateful inspection, proxy services and VPN supports.

What is a Gateway?

TCP/IP Layer:

• Internet Layer

Function:

• Provides a point of access between different networks, often using different protocols and allows networked devices to communicate. Gateways are crucial for protocol conversation, data format transformation and routing between different network architectures like between a corporate network and the internet.

Technical Details:

• N/A