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 802.3 (Raw) (No LLC information, supports IPX/SPX only) Ethernet 802.2 (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

Ethernet Standards Not all frame types can support all traffic variants. For example, NetWare IPX/SPX packets are usually transmitted by 802.3 (Raw) frames. In fact, the 802.3 (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.

Logical Link Control data Ethernet/IEEE 802.3 Frame Destin address Source address Logical Link Control data FCS 4 7 6 6 2 46 - 1500 octets Frame Check Sequence Preamble (for synchronization) (01010…0111) IEEE 802.2 LLC standard for access to higher layers. PAD may be added to ensure enough length for Collision Detection (CD) Type (Ethernet II, TCP/IP - 0800H, IPX - 8138H) Length (IEEE 802.3) If the value > 0x05-DC (decimal 1500), then Ethernet II

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

IEEE 802.2

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