Download WDM the Transmode way

An introduction to:
WDM for IP/MPLS service provider
networks
Anders Enström
Product Manager
Transmode Systems
Agenda







Basic WDM overview
CWDM & DWDM
Optical Amplifiers
WDM vs traditional fiber networks
Transponders & Muxponders
Flexible Optical Networks
Packet optical networks
 Objective
 Obtain a basic understanding
of WDM technology and how it is
used in networks
WDM Basics
Optical Transmission
100100111001...
Transmitter
Receiver
100100111001...
Optical fiber
 Optical transmission is the conversion of a digital stream
of information to light pulses
 The light pulses are generated by a laser source and
transmitted over an optical fiber
 The receiver converts the light pulses back to digital
information
Wavelength Division Multiplexing
Receiver
Transmitter
Transmitter
Optical fiber
Receiver
Transmitter
Receiver
Transmitter
Receiver
 Wavelength Division Multiplexing (WDM) is based on the
fact that Optical Fibers can carry more than one
wavelength at the same time
 The lasers are transmitting the light pulses at different
wavelengths that are combined via filters to one single
output fiber
Wavelength spectrum & attenation
Fiber
 Optical fibers have different Attenuation values over the wavelength
spectrum for lasers
 Attenuation limits the reach of the optical pulses by reducing the
optical power
 Best attenuation (0.25dB/km) is around 1550 – 1610 nm
CWDM & DWDM
Coarse Wavelength Division Multiplexing
 CWDM utilizes wavelengths from 1270 nm to 1610 nm
 Maximum 16 wavelength channels per fiber
 The bandwidth and spacing of the wavelengths allows
for cheaper laser and filter technology compared to
DWDM
Dense Wavelength Division Multiplexing
CWDM
Outside
DWDM-band
DWDM
C-band
DWDM
L-band
 The DWDM spectrums have more narrow bandwidth and spacing
compared to CWDM
 Increases total number of channels (typically 80) but lasers and filter
components are in general more expensive
 The ”C-band” is the most used due to the availability of Optical
Amplifiers
Summary CWDM & DWDM
 The choice between CWDM & DWDM is typically based
on:




Distance to bridge
Number of channels needed
Data rates used
Flexibility and expansion
 In general, CWDM is a cheaper technology more suitable for smaller
aggregation networks in metro or access, for data rates up to 10G
and reach up to 100km per span
 DWDM is a slightly more expensive technology suitable for larger
backhaul networks with complex traffic matrix and higher capacity,
with data rates up to 100G and reach up to 3000 km
Optical Amplifiers
Optical Amplifiers
MDU
MDU
OA
100km
100km
 Without amplifiers the reach is limited to 80-100km
before electrical regeneration
 Optical amplifiers boosts the attenuated wavelengths
and are more cost efficient than electrical repeaters
 Amplifier stations typically each 80-100km
 Depending on signal types and fiber characteristics,
Amplified DWDM reaches typically up to 1500 km
Optical networks with amplifiers
OK up to 80km
SDH
SDH
What if the link is 240km?
80km
SDH
SDH
80km
80km
SDH
SDH
What if you have optical amplifiers?
80km
SDH
OA
80km
OA
80km
SDH
What if you want more channels?
SDH
SDH
SDH
SDH
MDU
80km
80km
OA
80km
SDH
MDU
SDH
SDH
SDH
14
OA
Restricted
Summary Amplified networks
 Amplifiers are used in DWDM networks and increases
the reach of the optical signals up to 3000 km
 Amplifiers are a better choice than electrical repeaters
and are usually distributed each 80-100 km
 Amplifiers and DWDM filters are the two basic building
blocks for a powerful DWDM network
WDM vs traditional fiber networks
Dark fiber vs passive and active WDM
Dark fiber solution
+ low cost interfaces
+ no cost for passive equipment
- high cost for fiber rental (one service per fiber)
- long provisioning times
- less flexibility in the optical layer
- short reach
Passive WDM solution
+ no transponder cost
+ low cost for fiber rental
+ short provisioning times
- only possible for short distance
- no management or performance monitoring
TP
TP
TP
TP
17
Restricted
Active WDM solution
- transponder cost
+ low cost for fiber rental
+ short provisioning times
+ transponders and client equipment could be in different locations
+ management or performance monitoring
+ aggregating services in muxponders for better wavelength utilisation
+ advanced networking functions, e.g. Protection, FEC, ROADM
Traditional networks (ring example)
Cascaded nodes
leads to complex
redundancy
schemes
Different services (Ethernet,
SDH) requires separate fibers or
complex and expensive
equipment (Pseudowire, Ethernet
over SDH)
Same type of
equipment and
uplink interface in all
nodes
Shared resources
per fiber for all
nodes
WDM aggregation (ring example)
Redundancy per
individual channel
Dedicated
resources per node
– no sharing!
Easy mixing of
service types (SDH,
Ethernet, SAN etc.)
per node
Transponders & Muxponders
Transponders & Muxponders
WDM Node
Transponder
SDH/
SONET
ʎ1
ʎ1 ʎ2 ʎ3
ʎ2
IP Router1
WDM link
IP Router2
Muxponder
SDH/
SONET
ʎ3
Mux/Demux
Transponder
WDM
wavelength
Client side
Digital
Wrapper
Client signal
Transponder
Client
side
Line
side
l
TP
Generates the WDM
wavelength
Client
system
Client
system
ʎ
TP
Line
fiber
MDU
TP
MDU
Line side framing enables performance monitoring,
management channels and increased reach with FEC
Muxponder
WDM
wavelength
Client side
Digital
Wrapper
Client signals
Muxponder
Client
side
Line
side
MX
SDH
FC
l
P
Ethernet
Generates the WDM
wavelength
Client
systems
Client
systems
ʎ
MX
Line
fiber
P
MDU
PX
MDU
Line side framing enables performance monitoring,
management channels and increased reach with FEC
M
Summary Transponders & Muxponders
 Transponders and Muxponders provides wavelength
conversion from client to WDM signal
 A Transponder maps a single client to a single WDM
wavelength
 A Muxponder multiplexes several lower speed client
signals to a higher speed WDM wavelength, thus
increasing the network capacity
 The digital framing of a line signal from a Transponder or
Muxponder provides service monitoring, management
connectivity and increased reach
 The broad range of available Transponders &
Muxponders enables cost efficient solutions for both
CWDM & DWDM
Flexible Optical Networks
ROADM networks
ROADM – Reconfigurable
Optical Add/Drop
Multiplexer
• Used for increased
flexibility in the optical
paths
• Services can be
redirected upon failure
or capacity constraints
• Capacity can be
increased dynamically
per node
Basic ROADM principles
λ
λ
ROADM
ROADM
Mux
Mux
Flexible Optical Network – Key Components
Multidegree ROADM
8D ROADM
8D ROADM
λ
λ
ROADM
4D ROADM
Enables dynamic switching of services and
reconfiguration of capacity in the network
ROADM
2-D ROADM
λ
ROADM
8D ROADM
8D ROADM
Enables scalable growth of allocated capacity
per add/drop node
2D ROADM
λ
λ
λ
ROADM
ROADM
ROADM
Colorless MDU
MDU
Enables scalability and ”lambda-free” planning
and installation
TP
Tunable laser
28
Limited
Enables dynamic reconfiguration of services
down to the wavelength
Summary Flexible Optical Networks
 ROADM’s provide more flexibility compared to fixed
filters
 A wavelength can be redirected to another path if
necessary
 Capacity planning becomes easier with dynamic
expansion of add-drop wavelengths
 Remote software control – no site visits required
 Using ROADM’s, colorless filters and tunable lasers
provides extensive flexibility
 Efficient reuse of deployed investments
Packet-Optical
Transport Overview
Layer 1 Transport  Packet Optical Transport
Layer 1 Transport
Most suitable for:
 Carrier internal infrastructure
 Wholesale services
Characteristics:
 Point-to-point, fixed speed
 100% transparent (what goes in goes out)
 No service priority separation
IP Provider
Edge Router
~200M
each
3 x1G
1G
10G
10G
10G
S 5G
200M
10G
1G
Service = client interface
Wavelengths or sub-channels
for each service
Packet-Optical Transport
Most suitable for:
 Business Ethernet services (E-Line, E-LAN, …)
 IP access network
 Video distribuiton
Characteristics:
 Per-service routing, including multipoint
 Aggregation and QOS separation of services
 Flexible service rates
Mobile
Packet Core
1+1+1G
IP Provider
Edge Router
~200M
each
3 x1G
a,b,c
10G
10G
S 5G
10G
d,e
d
e
a,b,c
1G
200M
1G
Service definition not tied to interface speed
Services prioritized and aggregated within network
31
Confidential
Mobile
Packet Core
Native Packet Optical 2.0 for core agnostic service delivery
MPLS-TP over Ethernet
Native Ethernet
Packet over OTU
MPLS
(LSRs LERs)
L2 Services
 E-Line
 E-LAN
 E-Tree
 E-Access
Cisco
Juniper
Alcatel
Ericsson
IP Router
Ethernet
(SVLAN, ERPS, …)
Mobile SGW
OTN
(switching grooming)
Core network
agnostic
32
L3 Services
 Internet
 L3VPN
 IPTV
Confidential
λ
ROADM
WDM foundation Flexible Optical
Networks
Mobile services
 3G
 LTE
Transmode L2 Solutions
EMXP
EDU
Carrier Ethernet
Services
L2 Packet
Transport
NID
Flexible ROADMbased WDM
iSFP-TDM
33
Confidential
Summary
Summary
 WDM technology will increase the ability to scale a
network with more capacity without using more fibers
 CWDM for smaller aggregation networks
 DWDM for larger and more flexible networks
 Flexible optical networks will enhance your network
growth and reduce opex
 ROADM based networks superior in scalability and
flexibility
 Integrated L2 functionality will give you the ability to sell
advanced services directly over the fiber network and
reduce the cost of routers and switches
 MPLS-TP and CE2.0 services on a wavelength
Thank you!