NOS

segment

back bone

serial

Distributed

Collapsible backbone

parallel

DHCP

Lans

Wan

ICS

SCAD

DCS

PLC'S

7-Application
of the osi model

6- Presentation layer

5- Session layer

4-Transport Layer

3-Network Layer

2- Data Link Layer

1- Physical Layer

IEEE
stabdard

poE

poE+