Layer 1 (Physical) (obj 1.1) Flashcards
(17 cards)
What is the Physical Layer
Layer 1
Where transmission of bits across the network occurs and includes physical and electrical network characteristics.
Transition Modulation
If it changes during the clock cycle, then a 1 is represented (otherwise, a o is represented).
Asynchronous
Uses start and stop bits to indicate when transmissions occur from the sender to the receiver.
Synchronous
Uses a reference clock to coordinate the transmissions by both sender and receiver.
Broadband
Divides bandwidth into separate channels.
Baseband
Uses all available frequencies on a medium (cable) to transmit data.
Time-Division Mutiplexing (TDM)
Each session takes a turn, using time slots, to share the medium between all users.
Statistical Time-Division Mutiplexing (StatTDM)
Dynamically allocates the time slots on an as-needed basiis.
What devices operate at the physical layer
- Transceivers
- Repeaters
- Hub
- Media Converters
- Router (In a SOHO network)
Transmission Media
Classified as cabled or wireless
Cable Media (bound media)
Physical signal conductor between two nodes
Copper
Fiber Optic
Wireless (unbound media)
Uses free space between nodes using microwave radio
Physical Interface
Mechanical specification of the network medium
How the cable was constructed and how many pins
Or
Radio transceiver and antenna
Transceiver
The part of a network interface that sends and receives signals over the network media.
Repeater
A device that amplifies an electronic signal to extend the maximum allowable distance for a media type.
Hub
A multiport repeater, deployed as the central point of connection for nodes.
Media Converter
A device that converts one media signaling type to another.
