V5 byte (VT path overhead)
- The first byte of a VT SPE, provides the functions of error checking, signal label and path status.
- Continuous monitoring of anomalies or defects and payload composition at the path end or along the path
o Bits 1-2 provides error checking (BIP-2)
o Bit 3 is the REI-V (0 = no error, 1 = errors), that is sent back towards an originating VT PTE if errors were
detected by the BIP-2.
o Bit 4 is reserved for mapping-specific functions.
o Bits 5-7 provide the VT signal label
§ 000 Unequipped
§ 001 Equipped (non-specific)
§ 010 Asynchronous mapping for DS1
§ 011 Bit synchronous mapping for DS1
§ 100 Byte synchronous mapping for DS1
o Bit 8 is the VT path RDI-V normally set to zero unless there is an error condition (AIS)
TX150 e-Manual D07-00-023 Rev A02
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