Transcript - SigmaNet
LightPath Networking
1
Light Propagation
Light propagates due
to total internal
reflection
Light > critical angle
will be confined to the
core
Light < critical angle
will be lost in the
cladding
2
Fiber Types
Multi-Mode:
supports hundreds
paths for light.
Single-Mode:
supports a single
path for light
3
Fiber Types
Cladding
LED
Laser
Core
Cross section
Muliti Mode
Cladding
Core
Laser
Single Mode
Multi-Mode
50/62.5um core, 125um clad
Atten-MHz/km: 200 MHz/km
Atten-dB/km: 3dB @ 850nm
MMF has an orange jacket
Single-Mode
9um core, 125um cladding
Atten-dB/km: 0.4/0.3dB
1310nm/1550nm
SMF has a yellow jacket
4
Attenuation Vs. Wavelength
5
Degradation In Fiber Optic Cable
Attenuation
Loss of light power as the signal travels
through optical cable
Dispersion
Spreading of signal pulses as they travel
through optical cable
6
Technologies Available
Transmitters (Light Sources)
LED’s - 850/1310nm
Used with MMF up to 250Mb/s
Short distances <1 Km
Semiconductor Lasers – 850/1310/1550nm
VCSEL’s, Fabry Perot and DFB
1310/1550 can be used with MMF or SMF
Short to long distances
Low to High data rates (Mb/s to Gb/s)
7
FP and DFB Laser Spectrum
FP Laser Output
DFB Laser Output
FWHM=4nm
Optical Output
Power (mW)
B
Optical Output
Power (mW)
A
Wavelength
(nm)
Wavelength
(nm)
FP laser
FWHM=0.1nm
Emits multiple evenly spaced wavelengths
Spectral width = 4nm
DFB laser
Tuned cavity to limit output to single oscillation / wavelength
Spectral width = 0.1nm
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Which Laser Type is Better?
Fabry Perot
Ideal for low cost pt-pt
MMF or SMF
Not suitable for WDM
due to +/- 30nm
variation
Dispersion is a serious
issue at Gb/s rates
Distributed Feed Back
Used in wavelength division
multiplexing systems
Less susceptible to
dispersion than FP laser
Used for medium and long
haul applications
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Technologies Available
Receivers (Detectors)
PIN Photodiodes
Silicon for shorter ’s (eg 850nm)
InGaAs for longer ’s (eg 1310/1550nm)
Good optical sensitivity
Avalanche Photodiodes (APD’s)
Up to 50% more sensitivity than PIN diodes
Primarily for extended distances in Gb/s rates
Much higher cost than PIN diodes
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Dispersion - Single-Mode
Receiver
Transmitter
Time
FP and DFB lasers have finite spectral widths and transmit
multiple wavelengths
Different wavelengths travel at different speeds over fiber
A pulse of light spreads as it travels through an optical fiber
eventually overlapping the neighboring pulse
Narrower sources (e.g DFB vs. FP) yield less dispersion
Issue at high rates (>1Ghz) for longer distances (>50Km)
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Dispersion - Multi-Mode Fiber
Modal Dispersion
The larger the core of the fiber, the more rays
can propagate making the dispersion more
noticeable
Dispersion determines the distance a signal
can travel on a multi mode fiber
12
Attenuation
It is the reduction of light power over the length of the fiber.
It’s mainly caused by scattering.
It depends on the transmission frequency.
It’s measured in dB/km (
)
dB 10log10 ( Pout Pin )
13
Chromatic Dispersion (CD)
Light from lasers consists of a range of wavelengths, each
of which travels at a slightly different speed. This results
to light pulse spreading over time.
It’s measured in psec/nm/km.
The chromatic dispersion effects increase for high rates.
Source www.teraxion.com
14
Transmission Bands
Optical transmission is conducted in wavelength
regions, called “bands”.
Commercial DWDM systems typically transmit at
the C-band
Mainly because of the Erbium-Doped Fiber
Amplifiers (EDFA).
Commercial CWDM systems typically transmit at
the S, C and L bands.
ITU-T has defined the wavelength grid for xWDM
transmission
G.694.1 recommendation for DWDM transmission,
covering S, C and L bands.
G.694.2 recommendation for CWDM transmission,
covering O, E, S, C and L bands.
Band
Wavelength
(nm)
O
E
S
1260 – 1360
1360 – 1460
1460 – 1530
C
L
U
1530 – 1565
1565 – 1625
1625 – 1675
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Single Mode Fiber Standards I
ITU-T G.652 – standard Single Mode Fiber (SMF) or Non Dispersion
Shifted Fiber (NDSF).
The most commonly deployed fiber (95% of worldwide deployments).
“Water Peak Region”: it is the wavelength region of approximately
80 nanometers (nm) centered on 1383 nm with high attenuation.
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Single Mode Fiber Standards II
ITU-T G.652c - Low Water Peak Non Dispersion
Shifted Fiber.
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Single Mode Fiber Standards III
ITU-T G.653 – Dispersion Shifted Fiber (DSF)
It shifts the zero dispersion value within the C-band.
Channels allocated at the C-band are seriously affected
by noise due to nonlinear effects (Four Wave Mixing).
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Single Mode Fiber Standards IV
ITU-T G.655 – Non Zero Dispersion Shifted
Fiber (NZDSF)
Small amount of chromatic dispersion at Cband: minimization of nonlinear effects
Optimized for DWDM transmission (C and L
bands)
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Single Mode Fiber Standards
ITU-T
Standard
Name
Typical
Attenuation
value (C-band)
Typical CD
value
(C-band)
Applicability
G.652
standard Single
Mode Fiber
0.25dB/km
17 ps/nm-km
OK for xWDM
G.652c
Low Water
Peak SMF
0.25dB/km
17 ps/nm-km
G.653
DispersionShifted Fiber
(DSF)
0.25dB/km
0 ps/nm-km
Bad for xWDM
G.655
Non-Zero
DispersionShifted Fiber
(NZDSF)
0.25dB/km
4.5 ps/nmkm
Good for DWDM
Good for CWDM
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Multiplexing - WDM
WDM
Multiplexed signal
Signal 1
Signal 1
Signal 2
Signal 2
MUX
DEMUX
Signal 3
Signal 3
Single-mode Fiber
Signal 4
Signal 4
Wavelengths travel independently
Data rate and signal format on each
wavelength is completely independent
Designed for SMF fiber
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Multiplexing - WDM
WDM – Wave Division Multiplexing
Earliest technology
Mux/Demux of two optical wavelengths
(1310nm/1550nm)
Wide wavelength spacing means
Low cost, uncooled lasers can be used
Low cost, filters can be used
Limited usefulness due to low mux count
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Multiplexing - DWDM
DWDM – Dense Wave Division Multiplexing
Mux/Demux of narrowly spaced wavelengths
Up to 160 wavelengths per fiber
Narrow spacing = higher cost implementation
400 / 200 / 100 / 50 GHz Channel spacing
3.2 / 1.6 / 0.8 / 0.4 nm wavelength spacing
More expensive lasers and filters to separate ’s
Primarily for Telco backbone – Distance
Means to add uncompressed Video signals to
existing fiber
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Multiplexing - CWDM
CWDM – Coarse Wave Division Multiplexing
Newest technology (ITU Std G.694.2)
Based on DWDM but simpler and more robust
Wider wavelength spacing (20 nm)
Up to 18 wavelengths per fiber
Uses un-cooled lasers and simpler filters
Significant system cost savings over DWDM
DWDM can be used with CWDM to increase channel
count or link budget
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CWDM Optical Spectrum
20nm spaced wavelengths
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DWDM vs. CWDM Spectrum
1.6nm Spacing
dB
1470
1490
1510
1530
1550
1570
1590
1610
Wavelength
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xWDM Technology
Dense WDM
0,8 nm
1470
1490
Fine channel spacing,
0.8 nm typical
•
High precision
stabilization of Lasers
•
High component cost
/nm
1550
Coarse WDM
•
•
Wide channel spacing,
20 nm typical
•
Lower precision of
Lasers
•
Significantly lower
component cost
20 nm
1510
1530
1550
1570
1590
1610
/nm
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DWDM Migration
Capacity Expansion
1470
1490
1510
1530
1550
1570
1590
1610
/nm
•
Each CWDM channel can be utilized with 8 DWDM channels
•
Resulting maximum system capacity:
8 x 8 = 64 DWDM channels
•
CWDM and DWDM channels can be mixed
•
Soft migration path
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DWDM Migration
CWDM to DWDM Channel utilization
2,5 Gbps
:
8ch DWDM
ch2
:
ch8
CWDM
DWDM
ch1
CWDM & DWDM
ch8
•
8 channel DWDM system per CWDM channel
•
Soft migration path
•
Mixing of CWDM and DWDM channels
•
No interruption of CWDM channels
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Amplification CWDM vs. DWDM
80 km
80 km
Requires 1
amplifier per
wavelength
CWDM
wavelengths
C-band
(DWDM
wavelengths)
L-band
{
{
EDFA
1 EDFA
amplifies all
wavelengths
in the C-band
Requires 1
amplifier per
wavelength
EDFA: Erbium-doped Fibre Amplifier
DWDM is typically used for longer distance transport, because EDFA
amplifiers enable very long spans more cost-effectively than CWDM.
Amplifiers typically cost approximately US$ 20k or more
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How Much Capacity ?
100Gbps
Duo-binary
Wave-locker++
1b/s/Hz
16 symbol levels
– 4 bits per
symbol required.
256 symbol
levels – 8 bits
per symbol
required.
40Gbps
NRZ/CS-RZ/
Wave-locker+
10G overlay
0.4b/s/Hz
Duobinary
Wave-locker+
16 symbol levels
– 4 bits per
symbol
No issue
NRZ
0.1b/s/Hz
Reduced reach
Wave-locker
NRZ
0.2b/s/Hz
Reduced reach
No ROADMs
Wave-locker+
0.4b/s/Hz
100GHz
50GHz
25GHz
10Gbps
0.8b/s/Hz
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Optical Routing - Definitions
Optical Routers – Optical IN , Optical OUT
Photonic Routers – Optical IN & OUT but 100%
photonic path
OOO- Optical to Optical to Optical switching
Optical switch fabric
OEO- Optical to Electrical to Optical conversion
Electrical switch fabric
Regenerative input and outputs
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Photonic Technologies
MEMS (Micro Electro-Mechanical System)
Liquid Crystal
MASS (Micro-Actuation and Sensing System )
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MEMS Technology
Steer the Mirror
Tilted mirrors shunt light in various directions
2D MEMS
3D MEMS
Mirrors arrayed on a single level, or plane
Off or On state: Either deployed (on), not deployed (off)
Mirrors arrayed on two or more planes, allowing light to be
shaped in a broader range of ways
Fast switching speed (ns)
Photonic switch is 1:1 IN to OUT (i.e. no broadcast
mode)
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Liquid Crystal Technology
Gate the light
No Moving Parts
Slow switch speed
Small sizes (32x32)
Operation based on polarization:
One polarization component reflects off surfaces
Second polarization component transmits through
surface
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MASS Technology
Steer the fiber
Opto-mechanics uses piezoelectric actuators
Same technology as Hard Disk Readers and Ink
Jet Printer Heads
Small-scale opt mechanics: no sliding parts
Longer switch time (<10msec)
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OEO Technology
Fiber
Inputs
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
OE
Electrical
Inputs
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EQ
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
EO
High BW
Electrical
XPNT
Fiber
Outputs
X
Electrical
Outputs
Monitoring
Interface
CPU
Local
Indication
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OEO Routing
Optical <> Electrical conversion at inputs/outputs
High BW, rate agnostic electrical switching at core
SD, HD, Analog Video (digitized), RGBHV, DVI
Fast switching (<10us)
Full broadcast mode
Provides optical gain (e.g. 23 dB)
One IN to ANY/Many outputs
Build-in EO / OE to interface with coax plant
Save converter costs
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Regeneration - Optical vs Photonic
Photonic is a lossy device that provide no reamplification or regeneration
Signal coming in at –23dBm leaves at –25dBm
OEO router provides 2R or 3R (re-amplify,
reclock, regenerate)
Signals come in at any level to –25dBm
Leave at –7dBm (1310nm) or 0dBm (CWDM)
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Applications - Design Considerations
Types of signals
Signal associations
Fiber infrastructure
Distance/Loss
Redundancy
Remote Monitoring
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Types of Signals
FacilityLINK - Fiber Optics Platform
VIDEO
AUDIO
MULTI
WAVELENGTH OR
SDI
HDSDI
ANALOG
DVB-ASI
RGB
MULTI
FIBER
AES
ANALOG
DOLBY E
INTERCOM
OPTICAL
CONTROL
DATACOM
RF
TELECOM
WDM
CWDM
DWDM
RS232/422/485
GPI/GPO
10/100 ETHERNET
GBE
FIBER CHANNEL
SPLITTERS
+
PROTECTION
SWITCHING
ROUTING
70/140 MHz I/F
L-BAND
CATV
SONET OC3/12
T1/E1
DS3/E3
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Design Considerations
Fault Protection
Protection against fiber breaks
Important in CWDM and DWDM systems
Need 2:1 Auto-changeover function with
“switching intelligence”
Measurement of optical power levels on fiber
Ability to set optical thresholds
Revert functions to control restoration
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Design Considerations
Remote monitoring is key due to distance issues
Monitor
Input signal presence and validity
Laser functionality and bias
Optical Link status and link errors
Pre-emptive Monitoring
Input cable equalization level
CRC errors on coax or fiber interface
Optical power monitoring
Data logging of all error’d events
Error tracking and acknowledgment
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Design Examples – Single Link
-7dBm @ 1310nm
SDI @
270Mb/s
SD EO
-32dBm
40 Km’s
-7dBm @ 1310nm
HDSDI @
1.485Gb/s
HD EO
Loss Budget
SD
SD OE
-23dBm
40 Km’s
HD OE
SDI @
270Mb/s
HDSDI @
1.485Gb/s
Dispersion
HD
HD
FP
DFB
SD
HD
HD
FP
DFP
TX Power (dBm)
-7
-7
0
FP Line width (nm)
4
4
0.2
RX Sens (dBm)
-32
-23
-23
Dispersion (ps/nm.km)
2
2
2
Available Budget
25
16
23
Distance (km)
40
40
40
Distance (Km)
40
40
40
Dispersion (ps)
320
320
16
Fiber Loss
(0.35dB/km@1310)
14
14
14
RX Jitter Tolerance (UI)
0.4
0.4
0.4
Connectors
4
4
4
RX Jitter Tolerance (ps)
1480
270
270
Connector Loss
1
1
1
Headroom (ps)
1160
-50
254
Total Loss
15
15
15
Headroom
10
1
8
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Post House Facility Link – New
Location #2
Location #1
SDI @
270Mb/s
1310
HDSDI @
1.485Gb/s
E to O
O to E
O to E
E to O
E to O
O to E
O to E
E to O
HDSDI @
1.485Gb/s
Analog Video
Mux + EO
Demux+OE
Analog Video
Analog Audio
OE+Demux
EO + Mux
Analog Audio
Demux+OE
Analog Video
EO + Mux
Analog Audio
Analog Video
Mux + EO
Analog Audio
OE+Demux
GBE
10/100 Mb/s
Ethernet
RS422
CWDM D16
CWDM
M16
AES
SDI @
270Mb/s
2 Km’s
Gbe
Gbe
10/100
10/100
10/100 Mb/s
Ethernet
RS422
RS422
RS422
Mux +EO
Demux +OE
Demux +OE
Mux + EO
GBE
AES
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RF Typical
OverSatellite
fiber
optics
-Applications
Application With SNMP Monitoring
L-Band Downlink (950Mhz – 2250Mhz)
Vertical
LB EO
BPX-RF
LB OE
DA8-RF
Router
Horizontal
LB EO
BPX-RF
LB OE
LNB Power
Ethernet
/ SNMP
Ethernet
/ SNMP
Remote
SNMP
Monitoring
& Control
Ethernet
/ SNMP
Satellite
Receiver
Satellite
Receiver
Satellite
Receiver
Satellite
Receiver
Satellite
Receiver
Satellite
Receiver
Satellite
Receiver
HPA
C or Ku
Up Conv
IF OE
IF EO
DA-RF
Video Mod
DA-RF
Video Mod
BPX-RF
IF Uplink (70/140Mhz)
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Large Video MAN – Fully protected
KABC
Circle seven
KRCA
KNBC
2.3
7.3
KVEA
2.9
2.3
5.75
LA Zoo
2.3
Extra
KABC
Prospect
RSE
25 mi
25 mi
KCBS
CNN
1.1
KTLA
Ent ..
Tonight
Fox
TV
Gaming
Fox
Sports
KSCI
7.25
9 Net
Australia
1.1
1.5
1.1
2.7
2.1
CBS
VYVX
Fiber
4 mi
Dodger
Stadium
11 mi
1.5
0
2.5
Intelsat
RSH
RSK
0.5
5.5 mi
0.5
8 mi
8 mi
9.8 mi
5.5 mi
0.5
KTTV
One
Wilshire
6.2
7.5
E!
0.8
NCTC
7.25
Pac TV
0.7
KMEX
Japan
Telecom
0.75
Globesat
10.5
Direct
TV
13.5 mi
10.5
BT
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Single Fiber Technology
48
4Gbps CWDM Link
SANET, AMREJ – cheapest solution
Gigabit Ethernet,
Low cost switches as repeaters (Cisco 3550)
CWDM
Belgrade
Novi Sad
Subotica
CWDM
MUX/DEMUX
CWDM
MUX/DEMUX
110km
95km
HU
1GE 802.1q
Cisco 6509
Cisco 3550
Cisco 3550
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Modular xWDM System
Passive Optical Modules
CWDM ch 1
CWDM ch 2
CWDM ch 3
..
..
8 ch.
Mux
Demux
CWDM
line
Power1
CWDM ch 8
A/D
West
Passive Optical
ch 1
ch 2
..
A/D
East
Power2
ch 1
ch 2
A/D
West
ch 1
..
ch 4
..
A/D
East
ch 1
..
Ch 4
..
2 ch.
Add
Drop
Mux
4 ch.
Add
Drop
Mux
Line
West
Line
Interf.
Active Optical
Line
East
Line
West
Line
East
Options:
• 8 channels Mux/Demux
• 2 channels Add/Drop
• 4 channels Add/Drop
50
Modular xWDM System
Line Interface Modules
Standard
Duplex
Internal
Line
Power1
Standard
Simplex
Power2
Passive Optical
Internal
Line
Line
Interf.
Protected
West
Active Optical
Protected
East
External
West
Internal
West
External
East
Internal
East
Options:
• Standard Line Interface (duplex)
• Standard Line Interface (simplex)
• Protected Line Interface
• Add/Drop Line Interface
51
Modular xWDM System
Configurable Channels (CWDM Lambdas)
Wavelength
color code
•
1470 nm
gray
•
1490 nm
violet
•
1510 nm
blue
Power1
Power2
Passive Optical
•
1530 nm
green
Line
•
1550 nm
yellow
•
1570 nm
orange
•
1590 nm
red
•
1610 nm
brown
Interf.
Active Optical
52
Modular xWDM System
Configurable Channels (Local Interface)
Fiber Wavel.
MM
Speed
Power1
850 nm 1.25 Gbps
Power2
Passive Optical
SM 1300 nm 1.25 Gbps
Line
SM 1300 nm 2,48 Gbps
Interf.
Active Optical
53
Optical drop/insert mux
54
Multicast
Drop and continue – optical splitter pipes
IPTV multicast
Broadband Video – put them all on the one
wave-length
55
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57
58
59
60
61
62
63
64
65
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GMPLS: Technologies for
Dynamic Optical Networks
GMPLS standards are still evolving for optical networks
Growing interest for dynamic lightpath configurations
Meriton’s path management includes a number of GMPLS concepts
Meriton will implement GMPLS in step with customer’s key
requirements for mesh networking
OSPF routing on NEs (used for management network today)
GMPLS LMP for auto network discovery, lightpath testing, and cable miswiring
Pre-provisioned shared protection (enabled by GMPLS signaling)
Dynamic (best-effort) signaled protection
Operator signaled lightpaths (S-LPs)
Client on-demand wavelengths (O-UNI signaling)
Participation in initiatives such as Internet2 HOPI, CANARIE UCLP, etc.,
is critical
67