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SONET/SDH Introduction – What is the Difference Between SONET and SDH?

SONET/SDH Introduction – What is the Difference Between SONET and SDH?. Why SDH/SONET?. SDH (Synchronous Digital Hierarchy) and SONET (Synchronous Optical NETwork) are standards for interfacing optical networks. Simple multiplexing processes

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SONET/SDH Introduction – What is the Difference Between SONET and SDH?

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  1. SONET/SDH Introduction –What is the Difference Between SONET and SDH?

  2. Why SDH/SONET? • SDH (Synchronous Digital Hierarchy) and SONET (Synchronous Optical NETwork) are standards for interfacing optical networks. • Simple multiplexing processes • Easy access to various signals in a multiplexed high bit rate signal • A flexible and efficient way of networking • Network Distribution: Add/Drop capability • Network survivability: APS (Automatic Protection Switching) • Traffic Cross connection: capacity management, bandwidth management and protection route diversity • Support advance Network Management System (OAM&P) – Overhead bits for Fault, Configuration, Performance Monitoring, Security and Accounting management • Standardized interface can support multi vendor interworking, international connection and many different services; i.e. ATM, IP

  3. SONET/SDH Digital Hierarchy

  4. SDH and SONET Bit Rate Bit Rate SDH SONET OC-1(STS-1) STM-0 51Mb/s STM-1 155Mb/s OC-3 STM-4 622Mb/s OC-12 STM-16 2.48Gb/s OC-48 STM-64 9.95Gb/s OC-192

  5. What is different about SDH vs. SONET? • Together they are a set of global standards that interface equipment from different vendors. SDH is basically the international version of SONET, and SONET can be thought of as the North American version of SDH. • There are some slight differences between SONET and SDH. • The main differences are in the basic SDH and SONET frame formats, but SDH and SONET are essentially identical beyond the STS-3 signal level. The base signal for SONET is STS-1 and the base signal for SDH is STM-1. STS-3c is equivalent to STM-1 and the lower tributaries can be mapped interchangeably between the two formats from that point on.

  6. What is different about SDH vs. SONET? (Cont’) • In SDH, both electrical and optical signals are referred to as STM signals. • In SONET, however, electrical signals are called STS and optical signals are referred to as OC.

  7. SONET • Defined by Bellcore and ANSI T1.X committees • Base rate (High Order) is 51.84Mbps (STS-1) • STS-1 Synchronous Payload Envelope (SPE) = 50.112M used for carrying tributaries or a DS3 signal • Tributaries (Low Order) used for SONET are: • VT1.5 (SPE Trib) = 1.728M for carrying DS1 (1.544) • VT2 (SPE Trib) = 2.304M for carrying CEPT (E1, 2.048) • VT6 (SPE Trib) = 6.912M, Never “formalized” same rate as VT Group

  8. x1 Data VT Group x1 xN DS3 Broadband STS-N Payloads (High Order Payloads) Tributaries of Base Signal (Low Order Payloads) x7 STS-NSPE STS-1SPE VT6 SPE x1 x3 VT2 SPE E1 STS-N VT 2 VT 1.5 VT 6 VT1.5 SPE x4 DS1 SONET Hierarchy

  9. STS-1 SPE PayloadDS3 Mapped or7x VTG Mapped STS-1 Frame with VT Mapping 3 bytes 87 bytes STS-1 SPE Section OH 3 1 5 J1 B3 C2 G1 F2 H4 F3 K3 Z3 STS Pointer Line OH ptr VT Group VT Group VT Group VT Group VT Group VT Group VT Group Vx V T 1 5

  10. Points to Remember in SONET • The base layer is the STS-1 SPE • Single pointer to get to the STS-1 SPE (50MB level) • ALL tributary signals multiplex (via Pointer Processing) to the STS-1 SPE • Each STS-1 has it’s own path overhead • TOH is called Section and Line Overhead • SS bits (in H1) is set to 00 • Bellcore (Telcordia) Alarming and GR-820 Performance Monitoring • Other Nuances: • Path Trace is 64bytes, Orderwire is Mu-Law, Z bytes not used, No J2, APS is different

  11. SDH • Defined by ITU-T (previously CCITT) committees • Base rate (High Order) is 155.520 (STM-1) • Virtual Container 4 (VC-4) = 150.336M used for carrying tributaries or an E4 signal (or data) • Tributaries (Low Order) used for SDH are: • VC-11 = 1.728M for carrying DS1 (1.544) (rarely used in AU4) • VC-12 = 2.304M for carrying CEPT (E1) • Also a stuffing option for mapping VC11/1.5M to TU-12 • VC-2 = 6.912M Just gaining acceptance (TU-2-Mc) for data • VC-3 = 50.112M (Same as STS-1 SPE) used for E3 ANDDS3

  12. STM-1 STM-4 STM-64 STM-16 TU-11 TU-12 TU-3 AU-4-64c AU-4-16c TU-2 VC-12 VC-3 VC-4 VC-11 VC-4-16c VC-2 VC-4-64c C-4 C-11 C-2 C-3 C-4-4c C-12 x4 C-4-16c C-4-64c x64 x16 VC-4-4c x16 x4 AU-4 x4 TUG-3 TUG-2 AUG STM-n AUG AU-n VC-n SDH Hierarchy 9039.872Mb/s 2259.968Mb/s AU-4-4c 564.992Mb/s E4: 139.264Mb/s x3 x3 AU-3 High Order Payloads Containers of Base Signal (Low Order Payloads) E3: 34.368Mb/s DS3: 44.736Mb/s VC-3 x7 x7 x1 DS2:6.312 Mb/s Synchronous Transport Module Administrative Unit Group: One or more AU(s) Administrative Unit: VC + pointers Virtual Container: payload + path overhead x3 E1: 2.048Mb/s x4 DS1:1.544Mb/s

  13. STM-1 Frame with AU-4 Mapping 9 bytes 261 bytes Regenerator Section OH 3 1 5 VC-4 Payload:C4 or TUG-3 mapped J1 B3 C2 G1 F2 H4 F3 K3 N1 AU Pointer Multiplex Section OH H1 H2 H3 H1 H2 H3 H1 H2 H3 C-3 Payload C-3 Payload ptr TUG-3 TUG-2/VC12 Muxed J1 B3 C2 G1 F2 H4 F3 K3 N1 J1 B3 C2 G1 F2 H4 F3 K3 N1 Higher Order Path OH V C 1 2 Vx 5 bytes Low Order Path OH

  14. Points to Remember in SDH • The base layer is the VC-4 Container • Single pointer to get to the VC-4 • ALL Low Order (LO) Signals multiplex (via PP) to the VC-4 • Additional pointer to get to VC-3, the STS-1 equivalent: A FUNDAMENTAL DIFFERENCE between SONET and SDH • TUG-3 is NOT the same as an STS-1 • TOH is called Regenerator Section (RS) and Multiplex Section (MS) Overhead • SS bits (in H1) is set to 01 • ITU-T Alarming and ITU-T Performance Monitoring • Other Nuances: • Path Trace (P-API) is 16 or 64 bytes, Orderwire is A-Law, Z (N1) bytes used for TCM, APS is different

  15. SONET Vs. SDH • SONET UPSR = SDH SNCP (Sub-Network Connection Protection) • WTR is up to 12 minutes in 1 minute increments • “Hold-off” timer for SDH – 0-10S in 100mS increments • SONET BLSR = SDH MS-SPRing (Multiplex Section – Shared Protection Ring), SDH does not specify MS-SPRing @ STM-4 (but we allow it) • SONET APS = SDH MSP (Multiplex Section Protection) • SONET Mesh/ Virtual Ring = SDH Same as/Extension of SNCP (and this has been around a while in SDH Networks) • SONET Path Trace = SDH Path Access Point Identifier (P-API, or API) • SONET Alarms: CR, MJ, MN = SDH Alarms PMA (Prompt Maintenance Activity), DMA (Deferred Maintenance Activity): We kept the CR/MJ/MN and added the “-PMA/DMA as a suffix

  16. SONET Vs. SDH (cont…) • SDH Collects Errored Block Seconds, Errored Second “Ratios” • SDH is beginning to use Tandem Connection Monitoring – “Path within a path” • Adds additional Path Trace, BIP, FEBE and RDI to a high or low-order path • SONET, STS-SPE (50.112M) is the base-rate payload – SDH, the base is 155M and the VC-3 (STS equivalent) is a “tributary” to the VC-4 • It’s not a central office, it’s an “Exchange” • It’s not a Class 5/ Class 4, it’s a Local Switch and a Transit Switch • It’s not a DCS, it’s a DXC • SONET uses 3/3s and 3/1s, SDH uses 4/4s and 4/3/1s

  17. Terminology Summary Optical I/O Board Path Type

  18. Terminology Summary Protection Type Overhead Naming

  19. Terminology Summary Alarms

  20. Terminology Summary PM Monitored Types

  21. Terminology Summary PM Monitored Entities

  22. Terminology Summary PM Monitored Entities (Cont.)

  23. Cisco Systems 23 23 23

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