Hitachi US7070447-001 Benutzerhandbuch

Fundamentals of Networking

Doc Part Number, Version Number

5-3

The LLC sublayer defines the logical connection to the upper layer 
services based on a socket or Service Access Point (SAP).  This allows two 
processes on the same network to maintain a “logical connection” with 
each other for the purpose of data exchange.

This layer is where the network provides its routing functionality.  The 
Network Layer uses a packet to transport data from one network to another.  
A 32-bit address is used to define the network’s logical location and is 
referred to as the network address or IP address. 

This layer ensures reliable delivery of data between networks.  All error 
checking, acknowledgments, retransmissions, and data sequencing are 
handled by the Transport Layer.  

This layer provides for the ability for two processes on two different 
stations to form a connection for the purpose of communication with one 
another.  This is often referred to as a dialogue layer.  Host-to-host 
communication is established, managed, and terminated at this layer.

This layer converts the actual data that is being transferred into a readable 
and proper form.  

This layer provides network-based services to a user’s application.  The 
application layer communicates with the end user via programs such as file 
transfers (FTP, TFTP), electronic mail (SMTP), and other applications.