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Wide Area Networks (WAN) - Synchronous Digital Hierarchy (SDH)

Wide Area Networks (WAN) - Synchronous Digital Hierarchy (SDH). AAU Jens H. Sørensen jhaus@tdc.dk 20 Oktober 2005. Table of Contents. Objectives Introduction to WANs Typical WAN Technologies SDH Protocol SDH Equipment SDH Networks SDH Network Management SDH Services (partly 2nd part)

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Wide Area Networks (WAN) - Synchronous Digital Hierarchy (SDH)

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  1. Wide Area Networks (WAN) -Synchronous Digital Hierarchy (SDH) AAU Jens H. Sørensen jhaus@tdc.dk 20 Oktober 2005

  2. Table of Contents • Objectives • Introduction to WANs • Typical WAN Technologies • SDH Protocol • SDH Equipment • SDH Networks • SDH Network Management • SDH Services (partly 2nd part) • WDM/OTN (2nd part) • Network availability, restoration and automatic protection (2nd part) • Next/new Generation SDH and relations to IP, ATM, WDM, Ethernet … (2nd part) • Network Synchronisation (2nd part)

  3. Objectives Discussion of • LAN versus WAN, scaleability issues • WAN technologies, overview • Typical WANs, examples, SDH • Relations to networks based on Ethernet/IP/ATM/DSL … • Upcoming WAN networks

  4. SDH Services

  5. SDH Services • Leased line Services (fixed dedicated bandwidth): • 2 Mbit/s, n x 2 Mbit/s • VC-12, n x VC-12 • 34 Mbit/s, 45 M Mbit/s • VC-3, n x VC-3 • 140 Mbit/s • VC-4 • VC-4-4c, VC-4-16c • Grey fibres / WDM channels • add-on services • Alternative routing, Specific routing, automatic protection, various Service Level Agreements (SLAs)

  6. SDH services - Users

  7. SDH services - Users

  8. SDH services - Users

  9. SDH services - Users

  10. SDH services - Users

  11. Wavelength Division Multiplexing (WDM)

  12. WDM på 5 min WDM systems Passive WDM system- no active electronics- Reach up to appr. 40 km- no e2e management Optical amplified WDM system- Optical amplifiers (end points)- Optional mid-span optical amplifiers- Typical reach up to 700 km- e2e management possible WDM system characterisation- Number of possible channels- No. of channels in use- A channel can be inegrated or open- Geografical reach measured in no. of spans (= mid span amplifiers + 1)

  13. WDM network, 4 STM-N Rings

  14. WDM, OTN • WDM • Dense WDM • Coarse WDM • Optical Transport Networks, OTN • Direct switching of optical signals with specific wavelengths • Optical ADM • Optical XC

  15. Network Availability, Restoration and Automatic Protection • the five 9’s (99,999%)

  16. Alternative Routing and Protection Costumeraddress 1 Costumer address 2 Site 1 Site 2 ( ) Circuits with alternative routes Kunde adresse1 Kunde adresse2 Site 1 Site 2 ( ) Circuits with alternativeroutes (Costumer initiates protection) Costumer equipment Costumer equipment Kunde adresse1 Kunde adresse2 Site 1 Site 2 ( ) Protected Circuit(Service provider responsible for circuit protecion via costumer based equipment) SP equipment SP equipment

  17. Alternative Routes, Alternative Sites Circuit with alternative routes (cable) Circuit with alternative routes and sites

  18. Classification Protection SNC-P Trail Inherent monitoring MS Ring shared dedicated MS Non intrusive monitoring Linear MS shared VC dedicated MS VC

  19. Protection af Network Connections • Linear protection • 1+1 protection (dedicated) • 1 : N protection (dedicated or shared) Working TX RX Protecting RX TX Working RX TX Working RX TX Working Protecting

  20. Sub-network SNCP • Sub Network Connection Protection Protection in a sub-net or end-to-end • Operates at SDH path level (VC-12, VC-4) • simple protection (switching in RX equipment) Sub-network Working Sub-network Sub-network Protecting

  21. Protection af Network connections • Ring protection TX RX

  22. Multiplexer Shared Protection Ring (MSSPRING) Normal Cable fault between Node A1 and Node A6

  23. Eksempel på SNC beskyttelse

  24. Next/new Generation SDH and relations to IP, ATM, WDM, Ethernet …

  25. WAN Transport platforms - relations IP Packet Over Sonet(POS) withContiguous concatenation ATM SDH WDM FIBER 622 Mbit/s 155 Mbit/s 2,5 Gbit/s 34 Mbit/s 10 Gbit/s 40 Gbit/s 2 Mbit/s

  26. Data and SDH Transport "efficiency" Data SDH Efficiency Ethernet 10 Mbit/s C-3 (49.5 Mbit/s) 20% ATM 25 Mbit/s C-3 50% Fast Ethernet 100 Mbit/s C-4 (149 Mbit/s) 67% ESCON 200 Mbit/s C-4-4c (599 Mbit/s) 33% Fibre Channel 400 Mbit/s 800 Mbit/s C-4-4c 67% C-4-16c (2.4 Gbit/s) 33% Gigabit Ethernet 1 Gbit/s C-4-16c 42% 10 Gb Ethernet 10 Gbit/s C-4-64c 100% Solution: Virtual Concatenation

  27. Next Generation SDH • Virtual Concatenation • Generic Frame Procedure (GFP) • Link Capacity Adjustment Scheme (LCAS)

  28. VC-n1 VC-n1 LSP1 LSP1 VCX/VCG VCX/VCG LSP1 LSP1 LSP2 LSP2 VC-n2 VC-n2 Virtuel multiplexing of a block of VC-n's (VCG) STM-N STM-N

  29. X * VC-n = VC-n-Xv 1 C-n 2 C-n C-n-Xc C-n-Xc X C-n Virtual Concatenation VC-n-Xc transport through a VC-n only network 29

  30. Virtual Concatenation Transport efficiencies Data SDH Efficiency Ethernet 10 Mbit/s C-12-5c 92% ATM 25 Mbit/s C-12-12c 98% Fast Ethernet 100 Mbit/s C-12-46c C-3-2c 100% 100% ESCON 200 Mbit/s C-3-4c 100% Fibre Channel 400 Mbit/s 800 Mbit/s C-3-8c C-4-6c 100% 89% Gigabit Ethernet 1 Gbit/s C-4-7c 95% 10 Gb Ethernet 10 Gbit/s C-4-64c 100% 30

  31. Mapping Data • SDH, SONET and OTN provide fixed rate channels, with virtualconcatenation and LCAS to provide the best match • most Data transport is packet based • to map the different types of Data into a fixed rate channel anew mechanism is defined: Generic Framing Procedure (GFP)i.e. ITU-T recommendation G.7041/Y.1303GFP is a generic mechanism to carry any packet signal (Ethernet, Fiber channel, ESCON) over fixed rate channels VC-n, VC-n-Xc, VC-n-Xv and LCAS providing flexible adjustment of a VC-n-Xv channel 31

  32. Generic Framing Procedure FibreChannel other client signals Ethernet IP/PPP FICON ESCON GFP - Client Specific Aspects (payload dependent) GFP - Common Aspects (payload independent) SDH/SONET path other CBR path OTN path 32

  33. Link Capacity Adjustment Scheme (LCAS) • Bandwidth can dynamically change (eg. nxVC-12, nxVC-4) • "Hitless" change og bandwidth • Automatic adjustment of bandwidth in case of failure in one or more VC-n’s • Different up- og down bandwidth is supported • The combination of LCAS and VC enables ”cheap” protection

  34. Upcoming WANs

  35. Network Synchronisation

  36. Consequences in case of lack of synchronisation Slip rate = clock offset x frame rate x 86400 (s) pr. day For 2Mbit/s signals, frame rate = 8K frames/s : • 10-11 = 1 slip in 4.8 months • 10-10 = 1 slip in 14.5 days • 10-9 = 1 slip in 1.45 days • 10-8 = 6.9 slips per day • 10-7 = 2.9 slips per hour • 10-6 = 28.8 slips per hour • 10-5 = 4.8 slips per minute

  37. Necessary accuracy 1 sec per day ~ 1 / 86.400 = 11,6·10-6 Equipment in hold-over ~ 4,6·10-6 SASE oscillator ~ 2·10-10 Cæsium modul ~ < 1·10-11 (10-10 svarer til en nøjagtighed på ½ cm på jordens omkreds)

  38. The effect of Slips • Tale • Uncompressed - 5% slips medfører hørbare klik • Compressed - et slip vil medføre hørbart klik • Fax • Et slip kan fjerne flere linier • Modem • Et slip kan medføre adskillige sekunders drop out • Compressed video • Et slip kan fjerne flere linier • Flere slip kan fryse billedet i sekunder • Encrypted/compressed data protokol • Slip medfører reduceret båndbredde

  39. Netopbygning PRC G.811 Primær forbindelse STM-N Sekundær forbindelse SASE clock G.812 SASE clock G.812 SASE clock G.812 NATIONALT NETLAG STM-N SASE clock G.812 SASE clock G.812 SASE clock G.812 SASE clock G.812 REGIONALT NETLAG STM-N LOKALT NETLAG SASE clock G.812 SASE clock G.812 SASE clock G.812 SASE clock G.812

  40. Referencer • Tidsenhed - sekund (SI-enheden for tid) ”The second is the duration of 9.192.631.770 periods of the radiation corresponding to the transition between the two hyperfine levels of the fundamental state of the Cesium 133 atom” Tidligere anvendte man et sekund defineret som tiden for én jordrotation divideret med 86.400.

  41. Referencer (4) • GPS princip 4 satellitter nødvendig for (x, y, z, t)

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