Data Link layer divided into
functionality-oriented sublayers:
Logical Link
Control (LLC)
|
® Responsible
for flow and error control.
|
Media Access Control (MAC)
|
® Responsible
for Multiple Access resolution.
|
The upper sub-layer that is
responsible for flow and error control is called Logical Link Control (LLC)
layer; and the lower sub-layer that is mostly responsible for multiple
access resolution is called the Media Access Control (MAC) layer.
When nodes or stations are connected
and use a common link, called multi point or broadcast link, we need a
multiple access protocol to co-ordinate access to the link.
Multiple Access Protocols
|
||
® Random Access
Protocol
|
® Controlled Access
Protocol
|
® Channelization
Access Protocol
|
1.
ALOHA
2.
CSMA
3.
CSMA/CD
4.
CSMA/CA
|
1.
Reservation
2.
Polling
|
1.
FDMA
2.
TDMA
3.
CDMA
|
