LAB 3.2

3.1.2
Using Figure 3-1 define each layer of the OSI model in your own words and state what layer provides. Use your textbook or internet to support your answer.
Physical – Device Data Link – Physical address Network – Path determination Transport – End to end connections Session – internet Presentation – typing data Application – games, downloads
3.2.2
Using Figure 3-2 as a basis, complete the diagram to show the intermediate encapsulation provided by each layer.
Application Presentation Session | Data |
Transport | Segment |
Network | Packet |
Data Link | Frame |
Physical | Bit |

3.2.3
Briefly explain the deencapsulation steps in the communication from host B receiving a message from host A destined for an active application.
First the receiving computer synchronizes with the digital signal by reading binary numbers. After synchronizing is complete and it gets the whole frame and passes it to the layer above it which is the Data Link layer. Second the Data Link layer will do a Cyclic Redundancy Check (CRC) on the frame. Checking for errors and then strip off any information or header which was put on by the remote systems Data Link layer and pass the rest to the Network layer. Third the Network layer checks the IP address and if it matches the Network layer header is stripped off from the packet and passed to the Transport layer. Fourth the Transport layer processes the segment and rebuilds the data stream and acknowledges to the transmitting computer that it received each piece. Then sends the data stream to the upper layer Application.

3.2.4
Explain why routing devices do not need the upper layers of the OSI model to route traffic. What is the highest layer of the OSI model used by the router to decide where to forward traffic?
Because routers work primarily at