WEEK 2

TCP/IP (Transmission Control Protocol/Internet Protocol) - a set of protocols that establishing how

devices should communicate over the internet.

• Looks through how data is

o Formatted

o Addressed

o Transmitted

o Routed

o Received

OSI

1. Physical Layer: Deals with the physical transmission of raw data bits over a communication

medium.

2. Data Link Layer: Establishes, maintains, and terminates a link between two physically connected

devices. Adds MAC addresses.

3. Network Layer: Manages logical addressing and routing (e.g., IP addresses, routers).

4. Transport Layer: Responsible for end-to-end communication, error handling, and flow control.

Protocols: TCP, UDP.

5. Session Layer: Manages sessions between applications. Responsible for setting up, managing,

and tearing down sessions.

6. Presentation Layer: Translates data between the application and the network. Handles data

encryption and compression.

7. Application Layer: Provides services directly to users and applications, such as HTTP, FTP, DNS.

TCP/IP Protocol Layers

1. Application

a. Establishes connection between network services and applications

i. E.x. HTTP, SMTP, FTP

2. Transport

a. Manages delivery of packets between devices and ensures packets are delivered

without error

3. Data Link Layer

a. Seeks how the packets should be dealt with and routed

4. Network Interface

a. Manages how data is transmitted over a network (Ethernet, Wi-fi, etc)

Encapsulation - Adding a header to the data being passed through the layers

Decapsulation - the reverse process of removing the header

Example: encapstulation with sending emails!

• Application

o User types out an email

• Transport Layer

o The email is broken down into segments and given a TCP header

• Network Layer

o Each broken down segment is placed into a packet with an IP address

• Data Link Layer

o Packets are framed with a MAC address

• Physical Layer

o The frame is converted to bits and sent as electrical signals

Example: Decapsulation with receiving emails!

• Physical layer

o Converts bits back to frames

• Data Link Layer

o MAC addresses are removed

• Network Layer

o Frames are grouped up into packets

o IP addresses are removed

• Transport Layer

o Packets are placed into segments

o TCP header removed

• Application Layer

o Email is displayed on email application

Addressing • Require a source address and a destination address

Multiplexing - sending streams of info from multiple signals into a single signal to be transmitted over a

single link

Demultiplexing - seperating a single stream of info into individual signals (opposite of multiplexing)

IPv4 Addresses • 4 octets containing 8 Bits (32 bits total)

• E.x. 00100100|01010101|10101100|00110010