Token-Ring Data Packet
All communication between a local and remote station is accomplished by the transmission of a packet that contains token-ring headers and trailers as well as an encapsulated LLC Link Protocol Data Unit (LPDU).
The DLCTOKEN Frame Encapsulation figure (Figure 1) illustrates the token-ring data packet.
![This diagram shows the DLCTOKEN data packet containing the following: SD, AC, and FC (together with SD and AC consist of 3 bytes), destination address (6 bytes), and source address (6 bytes), routing information (m bytes), LPDU length (n bytes), CRC (4 bytes), ED and FS (together with ED consist of 2 bytes). A second line shows that LPDU consists of the following: DSAP address, SSAP address (together with DSAP address consist of 2 bytes), control field [1 (2) byte], and the information field (p bytes).](figures/qjZ3a0bob.jpg)
The token-ring data packet consists of the following fields:
| Item | Description |
|---|---|
| SD | Starting delimiter |
| AC | Access control field |
| FC | Frame control field |
| LPDU | LLC Link Protocol Data Unit |
| DSAP | Destination service access point (SAP) address field |
| SSAP | Source SAP address field |
| CRC | Cyclic redundancy check or frame-check sequence |
| ED | Ending delimiter |
| FS | Frame status field |
| m bytes | Integer value greater than or equal to 0 and less than or equal to 18 |
| n bytes | Integer value greater than or equal to 3 and less than or equal to 4064 |
| p bytes | Integer value greater than or equal to 0 and less than or equal to 4060 |
Note: SD, CRC, ED, and FS headers are added and deleted by the hardware
adapter.