1. TCP/IP Model
2. Application Layer
   1. HTTP, POP3, SMTP
3. Transport
   1. TCP, UDP
      1. Same layer interaction on different computers. i.e. acknowledgemtns
         1. *Two PCs use a protocol for a specific layer.
         2. *The protocol uses a header that is processed by the same layer on another PC.
      2. Adjacent-layer interaction on the same computer. i.e. error recovery where HTTP request TCP to provide this service
4. Internet / Network
   1. IP
   2. Main Function: Addressing and Routing
5. Link Layer / Data Link & Phisical
   1. Ethernet, PPP, Frame Relay, T1
   2. Ethernet
      1. Encapsulates the IP packet between the ethernet header and trailer
      2. Transmits the bits using the electricity flowing in the ethernet cable
   3. Main Functions: * Physical transmission of the data. * The protocols and rules that control the use of the physical media.
6. Data Encapsulation
7. Encapsulation Process
   1. Step 1: Encapsulate the data with application layer header (HTTP OK message is returned in HTTP header).
   2. Step 2: Encapsulate the data from the application layer inside a transport layer header( i.e. HTTP data encapsulated inside TCP sequencing header "for the purpose Acknowledgement")
   3. Step 3: Encapsulate the transport layer data inside a network layer "IP" header ( The source and destination IP address ).
   4. Step 4: Encapsulate the data supplied by the network layer inside a data link layer header and trailer "Ethernet header and trailer"
   5. Step 5: Transmit the bits ( The physical layer encodes a signal into the medium of transmission ).
8. OSI Model
   1. It has 7 layers. Each layer defines a set of networking functions
   2. It can be used as a standard of comparison to other networking models
   3. Everyone uses OSI model when describing IP or any other protocol or networking device such as a switch is a layer 2 device, a router is a layer 3 device.
9. Layers Definition
   1. Application Layer: 1- It provides an interface between the communications software and any application that need to communicate through the network. 2- It defines processes for user authentications.
   2. Presentation Layer: 1- It defines the data formats "i.e. ASCII text, binary, JPEG" 2- It defines Encryption.
   3. Session Layer: 1- It defines how to start, control and end conversations "sessions". This allows presentation leayer to have seamless view of an incoming stream of data
   4. Transport Layer: It focuses on issued related to data delivery "such as error recovery and flow control"
   5. Network Layer: It defines Logical Addressing, Routing "Forwarding" and path determination. * Rouging defines how routers forward packets to their final destination. * Logical Addressing defines how each device can have an IP that that can be used by routing process. * Path Determination refers to the work done by routing protocols to learn all possible routes and choose the best route.
   6. Data Link Layer: 1- It defines the rules that determine when a device can send data over a particular medium. 2- Also defines the format of a header and trailer that allows devices attached to the medium to successfully send and receive data.
   7. Physical Layer: * This layer refers to standards that deal with the physical characteristics of the transmission medium and how to activate and deactivate the physical medium.
10. Types of Network
    1. Enterprise Network
    2. SOHO: Small Office Home Network
11. Networking Models