1. Ethernet Standards IEEE802.3
Data Link Layer contains two sub-layers:
Media Access Control (MAC)
Logical Link Control (LLC)
Four generic Ethernet frame standards of IEEE 802.3
Ethernet (Raw) (No LLC information, supports IPX/SPX only)
Ethernet (contains LLC header, supports IPX/SPX and FTAM)
Ethernet II (no LLC header, uses Type instead of Length, supports IPX/SPX, TCP/IP)
Ethernet SNAP (with extended LLC capacities, support TCP/IP, IPX/SPX, AppleTalk Phase 2)
Network Layer
LLC Sub-Layer
MAC Sub-Layer
Physical Layer

2. Ethernet Standards
Not all frame types can support all traffic variants. For example, NetWare IPX/SPX packets are usually transmitted by (Raw) frames. In fact, the (Raw) frame type can only support IPX/SPX traffic. When TCP traffic is generated, the Ethernet II frame is often used. Some desktop LAN analyzers will employ Sub-Network Access Protocol (SNAP) frames.

3. Logical Link Control data
Ethernet/IEEE Frame
Destin
address
Source
address
Logical Link Control data
FCS 4 7 6 6 2
octets
Frame Check
Sequence
Preamble (for synchronization)
(01010…0111)
IEEE LLC standard
for access to higher layers.
PAD may be added to ensure
enough length for Collision
Detection (CD)
Type (Ethernet II, TCP/IP H, IPX H)
Length (IEEE 802.3)
If the value > 0x05-DC (decimal 1500), then Ethernet II

4. Logical Link Control Sub-layer
LLC header
Destin
address
Source
address
Type P A D
Data
FCS
Destination Service Access Point
(DSAP) 1 octet
Source Service Access Point
(SSAP) 1 octet
Control Field 1 octet

5. IEEE 802.2

6. More Ethernet Information