A.1. Decision Flow
Upon receiving a frame, use the flow chart in Figure 2 and Tables 1 and 2 to decode the protocol type.
| VALUE | PROTOCOL |
|---|---|
| 0x0800 | IP |
| 0x0806 | IP-ARP |
| 0x8035 | IP-RARP (rarely used) |
| 0x8137 | IPX |
| 0x809B | AppleTalk[] |
| 0x80F3 | AppleTalk ARP[] |
| 0x6001, 0x6002 | DEC MOP |
| 0x6003 | DECnet Routing Protocol |
| 0x6004 | DEC LAT |
| 0x6005, 0x6006 | DEC Diagnostics |
| 0x8038 | DEC Spanning Tree |
| 0x803D | DEC Ethernet Encryption |
| 0x803F | DEC LAN Monitor |
| Others | NA |
| [] | |
| [] | |
[] AppleTalk Phase 1 uses Type field encapsulation, with 0x809B as the Type value. AppleTalk Phase 2 uses SNAP encapsulation, with SNAP OUI = 0x08-00-07.
[] AppleTalk ARP Phase 1 uses Type field encapsulation, with 0x80F3 as the Type value. In Phase 2, AppleTalk ARP uses SNAP encapsulation, with SNAP OUI = 0x00-00-00.
Figure A.2. Figure 2 Protocol decision tree flowchart
| VALUE | PROTOCOL |
|---|---|
| 0x06 | IP[] |
| 0x42 | 802.1D spanning tree |
| 0xE0 | IPX/SPX (so-called 802.2 encapsulation) |
| Others | NA |
| [] | |
[] While this format is theoretically permissible, commercial IP devices do not use pure LLC encapsulation with the 0x06 SAP. Stations use either type field encapsulation (on Ethernet LANs) or RFC 1042 (SNAP, with 00-00-00 OUI) encapsulation (on non-Ethernet LANs).
NetBIOS is the only protocol considered that uses LLC Type 2 (connection-oriented LLC), so the parsing of NetBIOS is shown before the check of the LLC Control field. No known protocol uses 0xFFFF for its LLC DSAP ...
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