Chapter 1

Review: The OSI Reference Model And Routing

Seven layers of the OSI model:

• 7 Application> Provides network services to applications
  
  
• 6 Presentation> Handles code formatting/ data representation, negotiates data transfer syntax
  
  
• 5 Session> Establises/ maintains/ manages sessions between applications
  
  
• 4 Transport> Provides reliable transport/ assembly/ segmentation of data, End-to-end communications
                        windowing/ data transfer/ acknowledgement with retransmission/ TCP
  
• 3 Network> Implements logical addressing scheme, concerned with best path determination
                       IP/ Routing
  
• 2 Data Link> Physical addressing, access to physucal media, error notification, network topology, flow control
                        MAC address/ Hubs, bridges, switches          
  
• 1 Physical> Provides electrical/ mechanical means for activating and maintaining a physical link between systems
                      wiring   

The OSI model simplifies networking functions by dividing the aspects of network operations into less complex elements. Layering prevents changes in one area from effecting other areas.

Routing breaks up broadcast domains and provides beth path determination and switching.
                      The two types of routing are:

     Distance-vector> Uses distance/ direction to determine next hop

     Link-state> Each router contains an exact toplogy of the entire "network"  

-Home-

-Top-