3. What
???
Why
???
How
???
DWDM
What Dense Wavelength Division Multiplexing
Why
• Provides hundreds of Gbps of scalable transmission capacity
• Provides capacity beyond TDM’s capability
How
multiplexes a number of optical carrier signals onto a
single optical fiber by using different wavelengths (i.e. colors)
of laser light
10. OTM
OTM
OTM
OTM
OTM
OTM
OTM
OTM
Traditional Network with Repeaters, no WDM
75% fewer fibers
WDM Network
with Repeaters
OTM
OTM
OTM
OTM
OTM
OTM
OTM
OTM
75% less equipment
WDM Network with
Optical Amplifiers
OTM
OTM
OTM
OTM
OTM
OTM
OTM
OTM
11. CWDM – Coarse Wavelength Division Multiplexing
DWDM – Dense Wavelength Division Multiplexing
CWDM
Earlier two channels only(1550 nm Band & 1310 nm Band)
Provides 8 Channel using wavelengths (1271 -1611nm)
Channel spacing about 20 nm/18 channels
Limits the total optical span to somewhere near 60 km for a 2.5 Gbit/s
signal
Costly about non-WDM systems
DWDM
Provides 40 or 80 channels or can be more
Channel spacing 0.8 nm or o.4 even less than 0.4nm
12. DWDM – Dense Wavelength Division Multiplexing
Optical Fiber Communication(OFC):
• Method of transmitting information from one place to another place.
• Transmitted information is sending by pulses of light through an
optical fiber cable.
• Light forms an electromagnetic carrier wave that is modulated to carry
information.
N 2
N 1
N 1 > N 2
2
1
N1Sin 1 = N2Sin 2
Sinc = N2/N1
1 >= c
13. DWDM – Dense Wavelength Division Multiplexing
Optical Spectrum:
• Uses the light wavelengths around 850, 1300 and 1550 nm.
• These wavelengths having less attenuation and its falling in the infrared
region
Band Description Range (nm) Bandwidth (nm)
O band Original 1260–1360 100
E band Extension 1360–1460 100
S band Short 1460–1525 65
C band Normal 1525–1565 40
L band Long 1565–1625 60
U band Ultra-long 1625–1675 50
14. DWDM – Dense Wavelength Division Multiplexing
Components Of DWDM Systems:
Terminal Multiplexer
Terminal De-multiplexer
Optical Add-Drop Multiplexer
Optical Supervisory Channel (OSC)
Wavelength Converting Transponders
Optical Cross Connects (OXC)
Transceivers
Terminal Multiplexer:
• The terminal multiplexer actually contains one wavelength converting
transponder for each wavelength signal it will carry.
• Transponders receive the input optical signal, convert that signal into the
electrical domain, and retransmit the signal using a 1550 nm band laser.
• The terminal MUX also contains an optical multiplexer, which takes the
various 1550 nm band signals and places them onto a single fiber
15. Components Of DWDM Systems:
Terminal De-Multiplexer:
•The terminal de-multiplexer breaks the multi-wavelength signal back into
individual signals and outputs them on separate fibers for client-layer systems
to detect.
C
SC1
F
I
U
C
C
SC1
F
I
U
C
D
E
M
U
X
C
SC1
F
I
U
C
M
U
X
OTU C
C
OTU
OTU
OTU
16. Components Of DWDM Systems:
Optical Line Amplifier:
• Optical amplifiers is used to reduce the power loss and attenuation.
• Boost up the received weak signals to transmit further
F
I
U
F
I
U
SC2
Site B Site D
Optical Cross Connects (OXC) :
• It is a device used to change high-speed optical signals in a fiber optic
network, such as an optical mesh network
17. Components Of DWDM Systems:
Optical Add-Drop multiplexer :
• It accept only the certain wavelength on the fiber to be do the de-multiplexed
(dropped) and re-multiplexed(added) while enabling all other wavelengths
to pass..
Optical Supervisory Channel (OSC) :
• The OSC is used for remote node management, monitoring and control.
• Optical Supervisory Channel used for remote software upgrades.
• OSC Module is make ready for its own 1510 nm MUX/ DEMUX filter, the OSC
travels the same fiber as the DWDM stream.
21. About 256 NEs of NG-WDM OSN 8800/6800/3800 to build National Ph1 + Expansion
DWDM Network with ODUk ASON.
2 Fiber Cut Not OUT, High Reliability.
22. NLD
51 STM-16 (2.5G) Services provisioned .
17 STM-64 (10G) Services provisioned .
14 10G LAN ASON service provisioned.
26 GE Services provisioned.
Metro
06 STM-64 (10G) Services (Pune Metro)
01 STM-64 (10G) Services (Mumbai Metro)
07 GE Services provisioned.
01 STM-16 Services provisioned
10 Circles - GUJ, RAJ, MPD, HAR, MAH, MUM, APD, NDL,UPE, UPW
Board name
standard single wavelength
input value （dbm） 40
wavelength
standard single
wavelength output
value （dbm） 40
wavelength
Dain（dB）
full
wavelength max
output
TN12OAU101 -16 4 20-31 20
TN12OAU103 -20 4 24-36 20
TN12OAU105 -16 7 23-34 23
TN12OBU103 -19 4 23 20
23. SC1: SC1 processes one supervisory channel and receives/transmits
the optical signal from one direction.
SC2: SC2 processes two supervisory channels and receives/transmits
the optical signals from both directions.
SCC: System control and communication board (SCC) is the control
center of network element. It accomplishes all the management
functions and is responsible for the communication between the
equipment and network management system. It implements the order
wire overhead processing as well.
FIU: FIU (Fiber Interface Unit) is located in front of the supervisory
channel board and behind the amplifier unit in WDM system. It
converges C&L bands and supervisory channels, and then transmits over
single strand of fiber.
24. MCA: The MCA board can supervise central wavelength, power,
signal-to-noise ratio and other parameters of optical signals in real
time.
OAU: Generally applied to erbium doped fiber amplifier (EDFA) in
the WDM system. Amplifies optical signals in the fibers and
compensates signal attenuation caused by optical components and
fibers.
OBU: The EDFA optical module of the OBU board only has an optical
booster amplifier (BA) that works in the same way as OAU.
DCM: Dispersion compensation module is used to reduce the
dispersion.
MR2/8: 2/8 port multiplexing/de-multiplexing unit. Basically used at
OADM site
25. ASON(Automatic Switched Optical Network):
ASON is a new generation optical network that has the following features:
• Routes are selected automatically.
• Signaling controls the creation and removal of connections.
• Network connections are automatically and dynamically completed
Basic Concepts of ASON
The basic concepts related to the ASON are the three planes,
label switched path (LSP) and rerouting.
26. WDM ASON Trail:
WDM ASON Trail is classified into WDM ASON OCh Trail and
WDM ASON ODUk (k = 0, 1, 2, 3) Trail.
LSP:
Label switched path (LSP) is the path ASON services pass through. In an
ASON, to create ASON services is to create LSPs. On U2000, LSP is also
called ASON Trail
27. Rerouting:
Rerouting is a means of resuming services. When an LSP is disconnected
the source node queries and finds the best route to resume services. Then,
the initial node creates an LSP to transmit the service. After creating an LSP,
the source node deletes the original LSP.
Rerouting Lockout:
In some cases, rerouting is not required after failure in LSP. Then you
need to set rerouting lockout.
Rerouting Policy:
Diamond, gold and silver services all support the following four
rerouting polices:
• Use existing trails whenever possible:
During rerouting, the route of the new LSP overlaps the original route
whenever possible. This policy helps save network resources. When bandwidth
resources are insufficient, the service is more likely to reroute successfully.
• Do not use existing trails whenever possible
During rerouting, the route of the new LSP is separated from the
original route whenever possible. This policy is applicable to a network with
sufficient link resources.
•
28. Rerouting Policy:
• No rerouting constraint
During rerouting, the no rerouting constraint is computed for the
new LSP. Whether the new or old route resources are utilized again is not
considered. This policy chooses a route with the minimum cost as the new
route after rerouting according to network conditions.
•Use simulated section restoration
During rerouting, the services must reuse the original routes
without involving faulty spans. End-to-end rerouting is enabled only when
rerouting on the faulty spans fails, and thus service route can be controlled
and managed more easily.
Crank Back Mechanism:
The crank back mechanism during rerouting, optimization, and
creation of the wavelength/sub-wavelength LSP is supported . Has value
0,1,2,3
29. SLA Protection:
The ASON network can provide services of different QoS to different
clients.
The service level agreement (SLA) is used to classify services according to the service
protection. The rerouting time is related to the device type, interrupted service,
network resource and setting. The data are listed as follows only for reference.
Service
Protection and
Restoration
Scheme
Implementation Means Switching Time Rerouting Time
Diamond service
Protection and
restoration
Intra-board 1+1
protection, ODUk SNCP,
SW SNCP and rerouting
Less than 50 ms
The rerouting time varies with
the network size, capacity and
service types. For the typical
scenario of a four-NE mesh
network transmitting no more
than 40 wavelengths, the
rerouting time is counted in
seconds.
Gold service
Protection and
restoration
ODUk SPRing protection
and rerouting
Less than 50 ms
Silver service Restoration Rerouting -
Copper service
No protection
No restoration
- - -
Editor's Notes
In telecommunications and computer networks, multiplexing (also known as muxing) is a method by which multiple analog message signals or digital data streams are combined into one signal over a shared medium. The aim is to share an expensive resource. For example, in telecommunications, several telephone calls may be carried using one wire. Multiplexing originated in telegraphy in the 1870s, and is now widely applied in communications.
Frequency-division multiplexing (FDM) is inherently an analog technology. FDM achieves the combining of several digital signals into one medium by sending signals in several distinct frequency ranges over a single medium.
One of FDM's most common applications is cable television. Only one cable reaches a customer's home but the service provider can send multiple television channels or signals simultaneously over that cable to all subscribers without interference. Receivers must tune to the appropriate frequency (channel) to access the desired signal
Time-division multiplexing (TDM) is a digital (or in rare cases, analog) technology. TDM involves sequencing groups of a few bits or bytes from each individual input stream, one after the other, and in such a way that they can be associated with the appropriate receiver. If done sufficiently quickly, the receiving devices will not detect that some of the circuit time was used to serve another logical communication path.
Consider an application requiring four terminals at an airport to reach a central computer. Each terminal communicated at 2400 bit/s, so rather than acquire four individual circuits to carry such a low-speed transmission, the airline has installed a pair of multiplexers. A pair of 9600 bit/s modems and one dedicated analog communications circuit from the airport ticket desk back to the airline data center are also installed.
In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i.e. colours) of laser light. This technique enables bidirectional communications over one strand of fiber, as well as multiplication of capacity.
The term wavelength-division multiplexing is commonly applied to an optical carrier (which is typically described by its wavelength), whereasfrequency-division multiplexing typically applies to a radio carrier (which is more often described by frequency). Since wavelength and frequency are tied together through a simple directly inverse relationship, the two terms actually describe the same concept
a) Overcome fiber exhaust / lack of fiber availability problems (Better utilization of available fiber)
b) Space & Power savings at intermediate stations
c) Easier capacity expansion
d) Cost effective transmission
Channel spacing greater than 200GHZ is called as CWDM
Channel spacing greater than 100GHZ is called as WDM
Channel spacing lesser than 100GHZ is called as DWDM
Channel spacing lesser than 25GHZ is called as UDWDM
100GHZ = 0.8nm
Many CWDM wavelengths below 1470 nm are considered "unusable" on older G.652 specification fibers, due to the increased attenuation in the 1270–1470 nm bands
CWDM is also being used in cable television networks, where different wavelengths are used for the downstream and upstream signals. In these systems, the wavelengths used are often widely separated, for example the downstream signal might be at 1310 nm while the upstream signal is at 1550 nm.
The number of transmission modes in optical fibers varies with diameters of fiber cores. So optical fibers can be classified into single-mode optical fibers and multi-mode optical fibers according to the number of transmission modes:
When the diameter of an optical core is much bigger than the optical wavelength, the optical fiber supports dozens of transmission modes or more. This kind of optical fiber is a multi-mode one. The core diameter of a multi-mode optical fiber is relatively big, usually about 50 um.
When the diameter of an optical core is near to the optical wavelength, the optical fiber supports only one transmission mode. This kind of optical fiber is a single-mode one. The core diameter of a single-mode optical fiber is relatively small, usually 5–10 um.
The above two kinds of optical fibers have little difference in appearance. The diameter of an optical fiber with a plastic jacket is less than 1 mm.
Only single-mode optical fibers are used in WDM systems.
Attenuation or loss in an optical fiber is an important factor that restricts the propagation of optical signals and limits the optical transmission distance. Optical loss includes absorption loss, scattering loss and bending loss.
Absorption loss is caused by the optical fiber material, mainly including ultraviolet absorption, infrared absorption and contamination absorption.
Uneven density of material within an optical fiber causes light to scatter, which is called Raileigh scattering. This kind of loss is the intrinsic property of the fiber material — silicon dioxide.
The bending of an optical fiber causes radiation loss.
The optical fiber attenuation constant is mainly determined by absorption loss and scattering loss.
Advantages of Optical Fibers
we can Transfer high capacity of information. Less attenuation (order of 0.2 db/km). Size is very Small,and Small in diameter & light weight. Low cost as compared to copper. safet from the moisture & corrosion. Is dielectric in nature so can be laid in electically sensitive surroundings. No cross talk and disturbances
Disadvantages of Optical Fibers
The Destination equipment is more costly as compared to copper equipment. It is very sensitive ,so its should be handled carefully. Communication is not totally in optical domain, so repeated E-O-C is needed. Tapping is not possible. So we need Seperate equipment to tap a fiber. The splicing and testing equipments are very expensive as compared to copper equipments.
In a DWDM system, C band and L band are used because the attenuation in the two bands is the lowest.
In a CWDM system, multiple bands are used, ranging from 1311 to 1611 nm, because attenuation is not a major restrictive factor in short-distance transmission.
Control Plane
The control plane consists of a group of communication entities. It is responsible for the calling control and connection control, including automatic setting up, releasing, monitoring, and maintaining connections. The control plane automatically restores the failed connections through signaling exchange.
Transport Plane
The traditional WDM network is the transport plane. It transmits optical signals, configures cross-connection and protection switching for optical signals, and guarantees the reliability of all optical signals.
Management Plane
The management plane is a complement to the control plane. It maintains the transport plane, the control plane and the whole system. It can configure end to end service. Its functions include performance management, fault management, configuration management and security management.
WDM ASON Trail
WDM ASON Trail is classified into WDM ASON OCh Trail and WDM ASON ODUk (k = 0, 1, 2, 3) Trail. See Figure 2.
NOTE:
OptiX OSN 8800 series support WDM ASON ODU0 Trail.
The WDM ASON OCh trail can be created when there are sufficient OCh TE link resources.
The WDM ASON ODUk trail can be created when there are sufficient TE link resources where the payload type is ODUk.
Crankback Mechanism
The crankback mechanism during rerouting, optimization, and creation of the wavelength/sub-wavelength LSP is supported.
It takes a certain time to spread network routing information. When rerouting is performed, the source node may use the outdated network status information to calculate the trail. Therefore, the selected route may be unavailable, resulting in a rerouting failure.
The ASON software supports the crankback rerouting mechanism. When setting up connections according to the calculated trail, the ASON software informs the source node of the information related to the faulty network nodes or links if the connection setup process is baffled due to insufficient network resources or network faults. In this case, the source node recalculates a trail that meets the constraint conditions but does not traverse the obstacle node and then establishes the connections for the calculated trail. This effectively restores a service by means of rerouting
Crankback Mechanism
The crankback mechanism during rerouting, optimization, and creation of the wavelength/sub-wavelength LSP is supported.
It takes a certain time to spread network routing information. When rerouting is performed, the source node may use the outdated network status information to calculate the trail. Therefore, the selected route may be unavailable, resulting in a rerouting failure.
The ASON software supports the crankback rerouting mechanism. When setting up connections according to the calculated trail, the ASON software informs the source node of the information related to the faulty network nodes or links if the connection setup process is baffled due to insufficient network resources or network faults. In this case, the source node recalculates a trail that meets the constraint conditions but does not traverse the obstacle node and then establishes the connections for the calculated trail. This effectively restores a service by means of rerouting
