IEEE Standards for LANs: IEEE 802.3, 802.4, 802.5, and 802.11
The IEEE (Institute of Electrical and Electronics Engineers) developed the Project 802 standard to standardize local area network communications.
1. The Division of the Data Link Layer (LLC vs. MAC)
In the standard ISO OSI 7-layer model, Layer 2 is the Data Link Layer. The IEEE 802 committee split Layer 2 into two distinct sublayers:
+-------------------------------------------------------------+
| Layer 3: Network Layer (IP) |
+-------------------------------------------------------------+
| Layer 2b: Logical Link Control (LLC - IEEE 802.2) | <--- Upper Sublayer
+-------------------------------------------------------------+
| Layer 2a: Media Access Control (MAC - 802.3 / 802.11) | <--- Lower Sublayer
+-------------------------------------------------------------+
| Layer 1: Physical Layer (Cables, Connectors, Voltages) |
+-------------------------------------------------------------+- Logical Link Control (LLC - IEEE 802.2):
- Independent of the physical cable or medium used.
- Provides a common interface to the Network Layer (IPv4/IPv6). Handles error checking, flow control, and software addressing (SAP - Service Access Points).
- Media Access Control (MAC):
- Directly dependent on the physical hardware and transmission medium.
- Deals with 48-bit physical MAC addresses and collision protocols (CSMA/CD for Ethernet, CSMA/CA for Wi-Fi).
2. The Core IEEE 802 Standards You Must Know for Exams
The Key IEEE 802 Standards
IEEE 802.2
Logical Link Control (LLC) common upper interface
IEEE 802.3
Wired Ethernet LAN using CSMA/CD (10 Mbps to 100 Gbps)
IEEE 802.4
Token Bus LAN (Physical bus with logical token ring)
IEEE 802.5
Token Ring LAN (IBM token ring using star/ring wiring)
IEEE 802.11
Wireless LAN (Wi-Fi) using CSMA/CA protocol
Detailed Summary Table for Exams:
| IEEE Standard | Common Name | Physical Topology | Access Method | Typical Media |
|---|---|---|---|---|
| 802.3 | Ethernet | Star or Bus | CSMA/CD (Collision Detection) | Cat6 Twisted Pair, Optical Fiber |
| 802.4 | Token Bus | Bus | Token Passing | 75-ohm Broadband Coaxial Cable |
| 802.5 | Token Ring | Ring (Wiring Star) | Token Passing | Shielded Twisted Pair (STP) |
| 802.11 | Wi-Fi (WLAN) | Star (via Access Point) | CSMA/CA (Collision Avoidance) | 2.4 GHz, 5 GHz, 6 GHz Radio waves |
💡 DAVV Exam Tip
Question (10 Marks): “Explain the IEEE 802 standard architecture. Why was the Data Link Layer divided into LLC and MAC sublayers? Compare IEEE 802.3, 802.4, and 802.5.”
- Draw the LLC (802.2) and MAC sublayer division diagram.
- Explain LLC role: Software consistency for upper layers.
- Write the 4-row comparison table above.