Computer.Networking.A.TopDown.Approach.6th.Edition

1. Lecture 2: Introduction
Dr. Ameer Gouda

2. Contents
1. Layering and Reference Models
2. Encapsulation and PDU

3. Why Using Layer Models
 To visualize the interaction between various protocols,
it is common to use a layered model.
 Benefits of doing so:
Helps break down network function.
Create standard for equipment manufacturing.
Allows vendors to focus in specialized areas of the network.

4. Reference Models
Reference models describe the layers in a network
architecture as follows:
 OSI reference model (7 layer model)»
 TCP/IP reference model (Protocol model 4/5)»
 Model used for this text »

5. OSI Reference Model
 A principled, international standard, seven layer
model to connect different systems
– Provides functions needed by users
– Converts different representations
– Manages task dialogs
– Provides end-to-end delivery
– Determine the best path for packet
– Sends frames of information
– Sends bits as signals

6. TCP/IP Reference Model
 A four layer model derived from experimentation;
omits some OSI layers and uses the IP as the network
layer.

7. Model used in this course
It is based on the TCP/IP (5 layer) model

8. Protocol Data Units (PDU) and Encapsulation

9. Protocol Data Units (PDU) and Encapsulation