Frames
The Fibre Channel protocol transmits data in frames each of which can contain up to 2112 bytes of payload data. The structure of a frame is shown in this table:
| Field | Length |
| SOF - Start Of Frame | 4 |
| Extended header(s) | 0 or more |
| Routing Control | 1 |
| Destination ID | 3 |
| Class-Specific Control / Priority | 1 |
| Source ID | 3 |
| Data Structure Type | 1 |
| Frame Control | 3 |
| Sequence ID | 1 |
| Data Field Control | 1 |
| Sequence Count | 2 |
| Originator Exchange ID | 2 |
| Responder Exchange ID | 2 |
| Parameter | 4 |
| Data field | 0 to 2112 |
| CRC - Cyclic redundancy Check | 4 |
| EOF - End of Frame | 4 |
In addition to data frames, there are non-data frames that are used for setup and messaging purposes. These fall into three categories, link control frames, link service frames, and extended link service frames. The following table lists the most common ones:
| Mnemonic | Frame type | Meaning |
| ABTS | Link service | Abort Sequence |
| ACK | Link control | Acknowledge data frame (success) |
| BA_ACC | Line service | Basic accept |
| BA_RJT | Link service | Basic reject |
| F_BSY | Link control | Fabric busy |
| F_RJT | Link control | Fabric frame reject |
| FLOGI | Extended link service | Fabric login |
| NOP | Link service | No Operation |
| P_BSY | Link control | Port busy |
| P_RJT | Link control | Port frame reject |
| PLOGI | Extended link service | Port login |
| PRLI | Extended link service | Process login |
| PRLO | Extended link service | Process logout |
| PRMT | Link service | Dedicated connection preempted |
| RMC | Link service | Remove connection |
| RSI | Extended link service | Request sequence initiative |
Read more about this topic: Fibre Channel Network Protocols
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