COE768: Computer Networks (Week 3) - Reference Models and Network Layers

Reference Model

Specific modular design chosen for the network

OSI 7 Layer Reference Model

Example of a reference model with 7 layers

OSI

Open Systems Interconnection, developed in 1984

Application Layer

Layer for carrying out functions through protocols

Presentation Layer

Layer for formatting and translating data

Session Layer

Layer for establishing and managing sessions

Transport Layer

Layer responsible for connection control, flow control, error control

Network Layer

Layer for source-to-destination delivery of a packet across different networks

Data Link Layer

Layer for facilitating flow and error control between devices on the same network

Physical Layer

Layer for sending bits at the right frequencies through the medium

Internet Reference Model (TCP/IP)

Reference model used in practice, particularly for the internet

Protocol Data Unit

Name of the units of data on different layers in the TCP/IP reference model

Network Layer Devices

Devices responsible for routing in the network layer

Router

Main IP layer device for transferring packets

Hourglass Architecture

Architecture where the network layer implements minimal functionality for global interconnectivity

NIC Cards

Network interface cards, also known as ethernet cards or network adapters

MAC Address

Physical hardware identifier for network devices

Repeater

Device that provides signal amplification

Switch

Device that operates in layer 2 and uses MAC addresses to send frames

Network Layer Devices

Devices responsible for routing in the network layer

IP Addresses

Numerical labels used to identify hosts and provide their location in the network