Various LAN standards

IEEE has specified the following standards
The Institute of Electrical and Electronic Engineers.
LAN standards:
802.1d: Spanning tree.
802.2: LLC.
802.3: MAC ~ Ethernet.
802.5: MAC ~ Token ring.

802.11: Wireless LAN.
Logical Link Control (LLC): Transitions up to the network layer.
Media Access Control (MAC): Transitions down to media.
• LLC serves to communicate upward to Network layer, independent of the specific LAN technology used and Upper layer.
• MAC serves to access and communicate downward to the technology-specific
Physical layer.
LLC: receives a packet from the network layer and attaches a header it is called the PDU protocol data unit and sends to the MAC through the interface it is called the SDU service

data unit and through the service access point SAP. The header will have DSAP d stands for destination and SSAP s stands for the source.
MAC: does the framing and the flow control.
Concept of layer 2
1. Layer 2 uses framing to organize or group the data.
2. Layer 2 uses a flat addressing convention.
3. Layer 2 communicates with the upper-level layers through LLC.
4. Layer 2 uses MAC to choose which computer will transmit binary data, from a group in which all computers are trying to transmit at the same time.