The ETH-CSF protocol data unit (PDU) structure is detailed below.
The format of the CSF PDU used to support the ETH-CSF function is shown in the following figure.
The fields of the CSF PDU format are described in the following table.
| Field | Description |
|---|---|
| MEG Level | 3-bit field to carry the local MEG level |
| Version | 0 |
| OpCode | PDU type is CSF (52) |
| Flags | 3-bit Type sub-element and a 3-bit Period sub-element |
The format of the Flags field is illustrated in the following figure.
The Type field uses bits 6 through 4 to indicate the CSF type, with values as shown in the following table.
| Flags [6:4] | Type | Description |
|---|---|---|
| 000 | LOS | Client loss of signal |
| 001 | FDI/AIS | Client forward defect indication |
| 010 | RDI | Client reverse defect indication |
| 011 | DCI | Client defect clear indication |
The Period field uses bits 3 through 1 to indicate the transmission period, with values as shown in the following table.
| Flags [3:1] | Type | Description |
|---|---|---|
| 000 | Invalid value | Invalid value for CSF PDUs |
| 001 | For further study | For further study |
| 010 | For further study | For further study |
| 011 | For further study | For further study |
| 100 | 1 second | 1 frame per second |
| 101 | For further study | For further study |
| 110 | 1 minute | 1 frame per minute |
| 111 | For further study | For further study |
TLV Offset is set to 0.
End TLV is an all-zeroes octet value.