SDH/Sonet Label Space
Numbering scheme:
- For SDH, extension of G.707 numbering scheme (K, L, M)
- For SONET, field U = 0 = K (not significant). Only S, L and M fields are significant
- Each letter indicates a possible branch number starting at parent node in multiplex structure (increasing order from top of multiplex structure)
- S - indicates a specific AUG-1/STS-1 inside an STM-N/STS-N multiplex
- U - only significant for SDH, indicates a specific VC inside a given AUG-1
- K - only significant for SDH VC-4 (ignored for HO VC-3), indicates a specific branch of a VC-4.
- L - indicates a specific branch of a TUG-3, VC-3 or STS-1 SPE (not significant for unstructured VC-4 or STS-1 SPE)
- M - indicates a specific branch of a TUG-2/VT Group (not significant for unstructured VC-4, TUG-3, VC-3 or STS-1 SPE (M=0))