Layer 1 –
The Physical Layer
The physical layer of the OSI model defines
connector and interface specifications, as well as the medium (cable)
requirements. Electrical, mechanical, functional, and procedural specifications
are provided for sending a bit stream on a computer network.
Components
of the physical layer include:
•
Cabling system components
•
Adapters that connect media to physical interfaces
•
Connector design and pin assignments
•
Hub, repeater, and patch panel specifications
•
Wireless system components
•
Parallel SCSI (Small Computer System Interface)
•
Network Interface Card (NIC)
In
a LAN environment, Category 5e UTP (Unshielded Twisted Pair) cable is generally
used for the physical layer for individual device connections. Fiber optic
cabling is often used for the physical layer in a vertical or riser backbone
link. The IEEE, EIA/TIA, ANSI, and other similar standards bodies developed
standards for this layer.
Note:
The Physical Layer of the OSI model is only part of a LAN (Local
Area Network).
ref: www.globalknowledge.com