HP-UX HB v13.00 Ch-09 - Networking Basics

HP-UX Handbook – Rev 13.00 Page 5 (of 27)
Chapter 09 Network Basics
October 29, 2013
The OSI Reference Model illustrates the access of applications to the network. This
implementation is independent (from operating systems and hardware) and helps a lot in
heterogeneous networks. Table 1 shows the standardized terminology; the right column offers
some examples for the respective layer.
7
APPLICATION LAYER
consist of application programs that use the network
(i.e…telnet, ftp, DNS, etc)
6
PRESENTATION LAYER
standardizes data presentation to the application
(i.e…Mime, TLS, SSL, etc)
5
SESSION LAYER
manages sessions between applications
(i.e.. RPC Protocol)
4
TRANSPORT LAYER
provides end-to-end error detection and correction
(TCP or UDP Protocol)
3
NETWORK LAYER
manages connections across the network for the
upper layer
(IP-Adresses, Routing)
2
DATA LINK LAYER
provides reliable data delivery across the physical
link
(MAC-Adresses, Duplex-Mode)
1
PHYSICAL LAYER
defines the physical characteristics of the network
media
(Hardware)
Table 1 - OSI Layer
A network packet (the logical form how the information is transported via a network) contains
separate sections for each of these layers (as long as the layer is used in the specific
communication). Layers 1 through 4 are organized on behalf of the operating system and/or the
TCP/IP protocol. The layers above correspond to the applications.
While layers 1 through 3 are used by all applications, there are big differences in the upper
layers. Layer 4 stands for the method to organize a connection. Ordinarily the protocols UDP
and TCP are used here.