1. DWDM - OTN/ROADM Be smart when you plan your Network
Krzysztof Bondarczuk, PhD, MSc, Eng.
Network Implementation Engineer

2. Content Introduction to DWDM and OTN technologies
12/30/ :05 PM
Content
Introduction to DWDM and OTN technologies
OTN switching capability
OTN supported DWDM Network
Introduction to ROADM
Key ROADM elements
Example ROADM configurations
Conclusions
Key Message
SharePoint can be discussed using the feature set.
© 2008 Microsoft Corporation. All rights reserved. This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.

3. DWDM – Dense Wavelength Division Multiplexing
DWDM defines:
Transmission medium: Optical Fiber (SMF/LEAF)
All-optical signal regeneration 1R – Reamplificaiton (EDFA/RAMAN)
Channels multiplexing process
Transmitted frequencies/wavelengths (ITU Grid 40λ/80 λ /160 λ)
Optical modulation formats (NRZ, DRZ, ODB, DQPSK, PDM-BPSK, ePDM-QPSK)

4. OTN – Optical Transport Network
OTN is a technology defining mapping of numerous types of legacy protocols into a single optical signal - OTU (Optical Transport Unit) to support long haul DWDM transmission
Supports popular services: Ethernet, SONET/SDH, Fiber Chanel, ATM
Fully transparent to the transmitted protocols.
Supports transmission rates from 2.5G up to 100G ( shortly 400G)
Enhances long-haul transmission by implementing Forward Error Correction (FEC)

5. OTN Hierarchy

6. OTN Hierarchy
OTN provides separate layers between Client interfaces (Optical Data Unit layer) and DWDM Line interfaces (Optical Transport Unit Layer). Each layer has its own overhead containing separate set of alarms and communication bits

7. OTN Supported DWDM Network
Tributary cards map client services into ODU signal
Crossconnection card provides flexible switching matrix between tributary cards and line cards
Line cards convert ODU signal onto OTU signal prior to transmission
Service remains within OTU/ODU layers until its final destination.

8. OTU Frame Structure 1 7 8 14 15 16 17
3824
3825
4080
Alignm
OTUK
FEC
OTUk OH
OPU k payload
OPUk OH
Client signal
mapped in
OPUk payload
ODUk OH
Optical Payload Unit (OPU) Overhead– contains information about transported data type
Optical Data Unit (ODU) Overhead contains client side alarms and performance monitoring bits, provides communication bits between client side interfaces
Optical Transport Unit (OTU) Overhead contains line side alarms and performance monitoring bits, provides another set of communication bits between line interfaces
and FEC section contains redundant information for errors correction at the receiver side

9. OTU Frame Stape-by-Step

10. Forward Error Corretion
Forward Error Correction (FEC) is a technique of error control for data transmission, where the sender adds systematically generated redundant data to its messages
The carefully designed redundancy allows the receiver to detect and correct a limited number of errors occurring anywhere in the message without the need to ask the sender for additional data
FEC significantly improve OSNR range of the transmitted signal to maintain designated BER of the transmitted services over long haul distances

11. Forward Error Correction

12. OTN Cross-connections Capability

13. OTN Power Consumption
60A
60A
60A
60A
Total Maximum Power consumption in this configuration: 3261W (68A)
Hypothetical Maximum consumption 100A
Recommended configuration (2+2)63A on the power plant
Power Plants upgrades might be necessary
1Tbit/s (100x 10G) transmission
200 fibers to ODF
20 fibers to Mux/Dmux
Proper fiber management is a MUST

14. OTN Fiber Management
Single cabinet is designed to support 320 (2mm) internal fibers and 720 external cables
Power cable separation from optical fibers is strongly recommended (e.g. under floor electrical cabling and top fiber raceways)
Slack should be managed on the ODF not within cabinet
Additional side fiber management cabinets will significantly simplify day by day operation

15. OTN Fiber Management

16. OTN Summary
OTN technology allows for services grooming at the electrical level offering enhanced network flexibility and better bandwidth utilization.
OTN hierarchy allows for efficient data aggregation from access to the backbone layer
OTN naturally integrates with DWDM providing flexible scalable neworks
OTN Supports long haul transmission by implementing FEC

17. ROADM – Remote Optical Add/Drop Multiplexer
ROADM is a new approach for DWDM network design allowing for remote optical channels switching between multiple directions in order to reduce need for manual on-site intervention for new channels provisioning.
Key element of ROADM is Wavelength Selective Switch (WSS) replacing Arrayed Waveguide Grating (AWG) used in legacy DWDM networks

18. ROADM – Remote Optical Add/Drop Multiplexer
Very first WSS realizations were made based on Microelectromechanical systems ( Vulnerable to vibration and mechanical shock)
Recently Liquid Crystal on Silicon technology has been introduced for ROADM applications

19. ROADM – Remote Optical Add/Drop Multiplexer

20. 2D Directioned/Colored ROADM
Simplifies provisioning of pass-through waves
Site visit required for local terminal equipment reconfiguration
Excellent solution for remote nodes D 40 D 40 M 40 M 40
I T L 04-1
I T L 04-2
B104 A A
RDU 9
WSM 9
A101
A101
Direction 1/West
Direction 2/East
WSM 9
RDU 9
A101
A101 B B
B104
I T L 04-1
I T L 04-2 M 40 M 40 D 40 D 40

21. Multiple-D Directioned/ Colored ROADM

22. Directionless ROADM

23. Directionless ROADM

24. ROADM Insertion losses

25. ROADM Networks testing beyond 40G
In legacy DWDM networks channel performance was analyzed based on Out of Band OSNR measurements
in-Band OSNR could be interpolated based on out-off-band measurement
This is no longer possible for new modulation formats used for 40G ad 100G transmission since the channels occupy full 50GHz window and are partially overlapped.
The noise floor is no longer visible and cannot be easily measured
Some spectrum analyzers developed in-band OSNR measurement based on assumption the signal is fully polarized and the noise is fully depolarized
This technique however is no applicable for formats utilizing polarization multiplexing

26. ROADM Summary ROADM supports remote DWDM network reconfiguration,
Different locations can designed for the specific functonalieties
2D directioned/colored solution will will simplify pass-through channels configurations with minimal performance penalty.
Multiple-D directioned/colored solution perfectly suits remote sites
wave dropping can be implemented by local drop direction channel: colored or colorless.
For big terminal nodes with multiple directions, human on-site intervention is still most efficient approach however might be supported by directioned/colorless solution.

27. 400G
40G
Flex
100G
Trill
Cluster
FCoE
OTN
ASON
MS-OTN
8800
Thank You!