SDH

Synchronous digital hierarchy

  • SONET in US, SDH in Europe
  • requires central strict time sync
    • synchronize ≡ same frequency + delay is known = precise time is known
    • syntonize ≡ same frequency only, no phase info
  • PDH data can be encapsulated into SDH
  • no bit stuffing → data can be arbitrary unpacked
  • standardised
  • no upper bound for speed increase
  • TDM
  • 2 directions in ring: primary and backup
    • backup is used only after primary fails
    • 50ms failover (L1 OSI)
levelSpeed
STM-1155520
STM-2622080
STM-32488320
STM-49953280