The structure of the communication layer

1 Layer-Based Communication Model - hierarchical structure

- Layer N
   Use the services provided by the (N-1) layer
   Instance with the same hierarchy of communication

- Protocols
    For the communication between the tiers of the same predetermined protocol
 - Service
    The ability to provide the (N +1)-tier hierarchical N
    Also known as the Service Interface.
 - Instance
   Tier one communications protocol that provides services that implement


  2 ISO / OSI Reference Model

- Features
   Presents the abstract model for the communication between the system
   Standards development system for providing an open communication system
   Important feature of the communication system in terms of logical decomposition is recognized.
   Actually in a position to implement because of the complexity of the failed model

- Physical Layer (physical layer)
   Unstructured bit sequences converted to a physical signal transmitted through the media layer

- Data Link Layer (Data Link Layer)
   Transmitter transmits a frame made of data.
   Do not overload the receiver and adjust the flow of data.
   Error detection and re-transmission.
   Protocol: SLIP, PPP, HDLS, ...

- Network Layer (network layer)
  System connectivity between the networks.
   Routing, Fragmenting plays.
   Protocol: IP, ICMP, IGMP, ...

- Transport Layer (Transport Layer)
   Application provide data transfer between
   Exist for the accuracy of the data and to secure the order.
   Protocol: TCP, UDP, ...

- Session Layer (session layer)
   Handling the exchange of structured messages through the transport layer.

- Presentation Layer (presentation layer)
  Control the flow of data between the terminal system.
  The delivery of data in computer and communication systems that do not depend on (independent) regulations.
  Example: ASCII vs Unicode Big endian vs. Little endian

- Application Layer (Application Layer)

 
3 TCP / IP Reference Model

- Interface Layer
   Network adapter drivers and their covers.

- Internet layer
   IP
   ICMP - transfer control and error information
   IGMP - Communications Group

- Transfer layer
   Transfer terminal system applications among responsible
   TCP - connection-oriented, reliable, STREAM
   UDP - connection-oriented, stack light, DGRAM
             Complex (heavy) TCP are increasingly preferred over transfers (such as multimedia)

- Application layer
   Of all tasks associated with the application layer (ISO / OSI model of 5 ~ 7 layers)
   Telnet, FTP, SMTP, DNS, HTTP