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Agenda
Protocol
Layering
Why Simplify?
First Steps: MPS
Emerging Optical Switching Technologies:
Slide 1
Protocol Layering
Application
We know from experience
that we can't run applications
directly over media
Solution: Protocol Layering
FIBER
Slide 2
Protocol Layering
Application
Applications include…
• Leased lines
• National telephone services
SDH / SONET
Fiber
Slide 3
Protocol Layering
Application
IP
Internet services emerge
SDH / SONET
Fiber
Slide 4
Protocol Layering
Application
IP
PoA
PoS
ATM
ATM is introduced as…
• Traffic Engineering layer in
the Internet
• Native service
SDH / SONET
Fiber
PoA - Packet over ATM
GE - Gigabit Ethernet
PoW - Packet over WDM
PoS - Packet over SDH
Slide 5
Protocol Layering
Application
IP
PoA
ATM
Wavelength Division
Multiplexing appears as a
mechanism to increase
capacity on a fibre
SDH / SONET
WDM
Fiber
Slide 6
Native Ethernet services
appear to be a costeffective alternative, but
need SONET/SDH framing
Protocol Layering
Application
IP
PoA
PoS
ATM
GE
SDH / SONET
WDM
Fiber
Slide 7
Protocol Layering
MultiProtocol Label
Switching appears as
alternative to ATM Traffic
Engineering
Application
IP
PoA
ATM
MPLS
PoS
GE
PoS
SDH / SONET
WDM
Fiber
Slide 8
Protocol Layering
Digital Wrapper appears as
an early "SONET-lite"
technology for direct
Packet-over-Wavelengths
Application
IP
PoA
ATM
MPLS
GE
PoS
SDH / SONET
PoW
Digital Wrapper
WDM
Fiber
Slide 9
Data Transfer Over Framebased Networks
File
TCP
IP
Frame
(Ethernet,
FR, PPP)
Slide 10
Data Transfer Over Cellbased Networks
File
TCP
IP
Adaptation
ATM Cells
Slide 11
Agenda
 Protocol
Layering
 Why Simplify?
 First Steps: MPS
 Emerging Optical Switching Technologies:


Optical Packet Switching
Optical Burst Switching
Slide 12
What do these layers do?
 IP
IP
is the service
Addressing
 Routing

Over
ATM
 ATM
provides Traffic
Engineering
 SONET/SDH
provides…
Provisioning control
 Service restoration
 OAM statistics
 Low error rate

 WDM
provides capacity
SONET
SDH
WDM
Over
SONET/SDH
Over
DWDM
Slide 13
Control Plane v Data Plane
The data plane actually carries the
information while the control plane
sets up pathways through the data
plane
MPLS LSRs and MPS OXCs both
solve performance scalability
problem by decoupling control and
data planes
Slide 14
An IP Router:
The Data Plane
Control Processor
OUTPUTS
Outbound Packet
INPUT
Inbound Packet
Packet Backplane
Slide 15
An IP Router:
The Control Plane
Routing Table
Router Applications
eg. OSPF, ISIS, BGP
Control Processor
Packet Backplane
Routing Updates
Slide 16
Bandwidth Bottlenecks

Routing Protocols Create A Single "Shortest Path"
C1
C3
C2
"Longer" paths
become underutilised
Path for C1 <> C3
Path for C2 <> C3
Slide 17
Engineering-Out

The Bottlenecks
ATM Switches Enable Traffic Engineering
C1
C3
C2
PVC C1 <> C3
PVC C2 <> C3
Slide 18
What Is MPLS?
A Software Upgrade To Existing Routers
 MPLS…a
software upgrade?
+
Router
=
S/W
LSR
Slide 19
What Is MPLS?
A Software Upgrade To ATM Switches
MPLS…a
software upgrade?
+
ATM
Switch
=
S/W
ATM
LSR
Slide 20
ROUTE AT EDGE, SWITCH IN
CORE
IP
IP
IP Forwarding
#L1
IP
#L2
LABEL SWITCHING
IP
#L3
IP
IP Forwarding
Slide 21
MPLS: HOW DOES IT
WORK
TIME
UDP-Hello
UDP-Hello
TCP-open
Initialization(s)
Label request
IP
#L2
TIME
Label mapping
Slide 22
Forwarding Equivalence Classes
LSR
LER
LSR
LER
LSP
IP1
IP1
IP1
#L1
IP1
#L2
IP1
#L3
IP2
#L1
IP2
#L2
IP2
#L3
IP2
IP2
Packets are destined for different address prefixes, but can be
mapped to common path
• FEC = “A subset of packets that are all treated the same way by a router”
• The concept of FECs provides for a great deal of flexibility and scalability
• In conventional routing, a packet is assigned to a FEC at each hop (i.e. L3
look-up), in MPLS it is only done once at the network ingress
Slide 23
MPLS BUILT ON STANDARD IP
Dest
47.1
47.2
47.3
Out
1
2
3
Dest
47.1
47.2
47.3
Out
1
2
3
1 47.1
Dest
47.1
47.2
47.3
3
Out
1
2
3
1
2
3
2
1
47.2
47.3 3
2
• Destination based forwarding tables as built by OSPF, IS-IS, RIP, etc.
Slide 24
MPLS Takes Over
 MPLS
LSRs Enable Traffic Engineering
C1
C3
C2
LSP C1 <> C3
LSP C2 <> C3
Slide 25
MPLS Path Creation:
Quality of Service Refinements

Source device (S) determines the type of path on the basis of the data
S
D
Low delay (preferred for VoIP traffic)
High bandwidth (preferred for FTP)
Slide 26
Typical IP Backbone (Late
1990’s)
Core
Router
Core
Router
ATM
Switch
ATM
Switch
MUX
SONET/SDH
ADM
SONET/SDH
DCS
MUX
Core
Router

SONET/SDH
ADM
SONET/SDH
DCS
SONET/SDH
ADM
ATM
Switch
MUX
SONET/SDH
ADM
MUX
ATM
Switch
Core
Router
Data piggybacked over traditional voice/TDM transport
Slide 27
IP/PPP/HDLC packet
mappings to SONET
frames (OC-48, OC-192)
IP routing protocols
(OSPF, BGP)
Gigabit IP Router
SONET
Point-to-point
DWDM links
(Linear or ring
SONET
topologies)
SONET
Demux
Mux
Wavelength laser
transponders
Slide 28
Slide 29
Why So Many Layers?

Router

MUX
Packet switching
 Speed match router/ switch
interfaces to transmission
 Multiplexing and statistical
network
gain
 SONET/SDH
 Any-to-any connections
 Restoration (several seconds)
 Time division multiplexing
(TDM)
 ATM/Frame switches
 Fault isolation
 Hardware forwarding
 Restoration (50mSeconds)
 Traffic engineering


Restoration (sub-second)

DWDM
Raw bandwidth
 Defer new construction


Result
 More vendor integration
 Multiple NM Systems
 Increased capital and operational costs
Slide 30
IP Backbone Evolution
Core
Router
(IP/MPLS)
 MUX
FR/ATM
Switch

IP trunk requirements
reach SDH aggregate
levels

Next generation
routers include high
speed SONET/SDH
interfaces
MUX
SONET/SDH
becomes redundant
Core
Router
(IP/MPLS)
SONET/
SDH
DWDM
DWDM
(Maybe)
Slide 31
Collapsing Into Two Layers
IP Service (Routers)
Optical Core
Optical Transport
(OXCs, WDMs,
SONET ?)
Slide 32
WDM Network Architecture
Core Router
STM-16
STM-64
POS
Core Router
Transponder
Transponder
O/EO
O/EO
OA
WDM
Mux/demux
WDM
Mux/demux
Slide 33
IP core routers with optical interfaces will be interconnected to DWDM equipment via a
transponder device.
Transponders perform the function of translating a standard optical signal (normally at
1330 nm) from a router line card to one of several wavelengths on a pre-specified grid
of wavelengths (sometimes called 'colors') as handled by the DWDM equipment.
This could be used to implement an OC-48 or OC-192 circuit between core routers in
an IP backbone.
It is worth pointing out that packet-over-SONET (POS) interfaces are used, so there is
SONET framing in the architecture to provide management capabilities like inline
monitoring, framing and synchronization.
The architecture is still referred to as IP-DWDM as there is no discrete SONET
equipment between the core routers and the optical transmission kit. The optical link
might also include optical amplifiers and, if the distance is large enough, electronic
regeneration equipment.
Slide 34
It is very important to differentiate between functional layers and layers
of discrete equipment.
In the diagram, many functional layers can be integrated within a single
equipment layer.
This is emphasized by the multilayer stack on the right hand side, which
involves two discrete layers of equipment, IP routers and DWDM
transmission.
In the case of IP routers, there are actually four distinct functional layers
(IP, MPLS, PPP and SDH).
The notion of collapsed layers is therefore only applicable to the number
of network elements involved, rather than the numeric of functional
layers. It is perhaps more meaningful to refer to increasing integration of
transmission network architectures
Slide 35
The Problem
 Should
carriers control their next-generation
data-centric networks using only routers, or
some combination of routers and OXC
equipment?
 The
debate is really about the efficiency of
a pure packet-switched network versus a
hybrid, which packet switches only at the
access point and circuit switches through
the network.
Slide 36
Slide 37
Slide 38
Node B: Nodal Degree of 2, 100/fiber
2X2X100 ports to add/drop
OXC
OXC
OXC
(IP-aware)
OXC
CONTROLLER
(IP-aware)
OXC
(IP-aware)
OXC
Transponder
Interface
CONTROLLER
IP/MPLS
module
Transponder
Interface
CONTROLLER
Tx’s Rx’s
Transponder
Interface
IP/MPLS
module
Transponder
Interface
Transponder
Interface
Transponder
Interface
IP/MPLS
module
Tx’s Rx’s
Local Add / Drop
Tx’s Rx’s
Local Add / Drop
Node B
Local Add / Drop
Node A
Node C
Slide 39
IP over Optical Network
Architectural Models
Slide 40
We Need Optical Traffic
Engineering
Classically
the NMS
the OXC "control plane" is based on
Relatively slow convergence after failure
(from minutes to hours)
 Complicates multi-vendor interworking
Traffic Engineering is achieved via a
sophisticated control plane…

Dynamic or automated routing become
proprietary
 Complicates inter-SP provisioning

Slide 41
Solution: Optical Switching
 All-optical
Data Plane products are widely available today
 Typically DWDM OADMs and OXCs
 Some of these devices have dynamic reconfiguration
capabilities
 Generally via NMS or proprietary distributed routing
protocols
 The Control Plane of these devices remains electronic
 So control messages must be sent over a lower
speed channel
 There are several ways to achieve this
 Typical DWDM is "service transparent"
 The data plane does not try to interpret the bitstreams
 Implies amplification, not regeneration
 Also implies that signal bit error rate is not monitored
Slide 42
Lambda Switching Objectives
Foster
the expedited development and
deployment of a new class of versatile
OXCs, and existing OADMs
Allow
the use of uniform semantics for
network management and operations
control in hybrid networks
Provide
a framework for real-time
provisioning of optical channels in
automatically-switched optical networks
Slide 43
How Do We Label a Lambda?
Remember
that the OXC is "service transparent"
 Will not interpret the bitstream
 May not even be able to digitally decode bits
at this speed
The
obvious property available is the value of the
wavelength
 This is why we call it "Lambda Switching"
Slide 44
Concepts in Lambda
Switching
 Involves
the idea of space-switching channels from an
inbound port to an outbound port

Variety of space-switching technologies are appropriate
 May involve wavelength translation
 Wavelength translation is expensive
 If
at the outbound port
data channels are "service transparent", how do we…



Exchange routing protocols?
Exchange signalling protocols?
Send network management and other messages that must
terminate in the lambda switch?
Slide 45
Recap: MP Label S
A technique
that uses IP as the control plane for
a connection-oriented, switched data plane
Initial application (focussed on reducing costs)
 Traffic Engineering (put the traffic where the
bandwidth is)
Emerging Applications (focussed on additional
revenues)
 VPNs
 Voice over MPLS
 ”Video over MPLS"
Future Applications
 Universal Control Plane
Slide 46
The Label Information Base
Connection Table
5
Port 1
Port 2
In
(port,Label)
Port 3
Port 4
7
Out
(port, Label, Operation)
(1, 5)
(4, 7, Swap)
(1, 3)
(4, 27, Swap)
(1, 17)
(4, 123, Swap)
(2, 3)
(3, 17, Push)
 Labelled
packet arrives at Port 1, with Label value "5"
 LIB entry indicates switch to Port 4, and swap label to
value "7"
Slide 47
The Optical Connection Table
Case 1a: No wavelength translation
Connection Table
2
Port 1
Port 2
Port 3
Port 4
2
In
(port,Lambda)
Out
(port, Lambda)
(1, 2)
(4, 2)
(1, 3)
(4, 3)
(1, 1)
(4, 2)
(2, 1)
(3, 1)
arrives on Port 1 on 2, the "green" lambda
 Connection table indicates that this channel should be
space-switched to Port 4
 At Port 4, 2 is available for onward transmission
 Channel
Slide 48
The Optical Connection Table
Case 1b: No wavelength translation
Connection Table
3
Port 1
Port 2
Port 3
Port 4
3
In
(port,Lambda)
Out
(port, Lambda)
(1, 2)
(4, 2)
(1, 3)
(4, 3)
(2, 3)
(4, 1)
(2, 1)
(3, 1)
arrives on Port 1 on 3, the "blue" lambda
 Connection table indicates that this channel should be
space-switched to Port 4
 At Port 4, 3 is available for onward transmission
 Channel
Slide 49
The Optical Connection Table
Case 2: Wavelength translation
Connection Table
Port 1
3
Port 2
Port 3
Port 4
1
In
(port,Lambda)
Out
(port, Lambda)
(1, 2)
(4, 2)
(1, 3)
(4, 3)
(2, 3)
(4, 1)
(2, 1)
(3, 1)
arrives on Port 2 on 3, the "blue" lambda
 Connection table indicates that this channel should be
space-switched to Port 4
 At Port 4, 3 is already in use, so lambda is translated to
1, the "red" lambda
 Channel
Slide 50
New Concept: MP Lambda S
Today: NMS Configuration
 Each
optical trail is set up in Service Provider NOC
NMS
OADM
OADM
OXC
OXC
OXC
OXC
Slide 51
New Concept: MP Lambda S
Today: NMS Configuration
 Each
optical trail is set up in Service Provider NOC
NMS
OADM
OADM
OXC
OXC
OXC
OXC
Slide 52
New Concept: MP Lambda S
Today: NMS Configuration
 Each
optical trail is set up in Service Provider NOC
NMS
OADM
OADM
OXC
OXC
OXC
OXC
Slide 53
New Concept: MP Lambda S
Today: NMS Configuration
 Each
optical trail is set up in Service Provider NOC
NMS
OADM
OADM
OXC
OXC
OXC
OXC
Slide 54
New Concept: MP Lambda S
Today: NMS Configuration
 Final stage is to enable connection in CPE
 eg. Manual Traffic Engineering of LSP to OCT
devices
NMS
OADM
OADM
OXC
OXC
OXC
OXC
Slide 55
New Concept: MP Lambda S
OXCs take part in routing
 Enhance
OSPF-TE and ISIS-TE to include opticalspecific metrics and parameters
NMS
OADM
OADM
OXC
OXC
OXC
OXC
Optically-enhanced routing protocol exchange
Slide 56
New Concept: MP Lambda S
CPE uses Optical UNI Signalling
 Must
create an Optical UNI spec.
NMS
OADM
OADM
OXC
OXC
OXC
OXC
Optical UNI signalling protocol
Slide 57
New Concept: MP Lambda S
OXCs create optical trail
 May
be based on signalled constraints, and may include
policy-driven permission
NMS
OADM
OADM
OXC
OXC
OXC
OXC
NMS notification, and/or policy exchange process
Slide 58
LSP to OCT Mapping
Granularity Issues
OCT #1
LSP #1
LSP #1
OCT #2
LSP #2
LSP #2
Lambda
Switch
LSR
W
D
M
W
D
M
Lambda
Switch
LSR
 LSP
#1 and LSP #2 are 64kbps IP "telephone calls"
 OCT #1 and OCT #2 are 10Gbps wavelengths

Utilisation of each OCT would be 0.00064%
Slide 59
LSP to OCT Mapping
Solution: LSP aggregation at LSR
OCT #1
LSP #1
LSP #1
...
...
LSP #n
LSR
LSP #n
Lambda
Switch
W
D
M
W
D
M
Lambda
Switch
LSR
 LSR includes path merge function ( )
 LSP constraints are observed
 Optimum OCT utilisation can be maintained
 Constitutes a set of "nested LSPs"
 Outermost label becomes the wavelength
Slide 60
Operational Approaches:
Overlay and Peer Models

Overlay model






Two independent control planes
 IP/MPLS routing
 Optical domain routing
Router is client of optical domain
Optical topology invisible to routers
Routing protocol stress – scaling issues
Does this look familiar?
?
Peer model




Single integrated control plane
Router and optical switches are peers
Optical topology is visible to routers
Similar to IP/MPLS model
Slide 61
The Hybrid Model

Hybrid model

Combines peer & Overlay
Middle ground of 2
extremes
Benefits of both models

Multi admin domain support
Derived from overlay
model

Multiple technologies within
domain
Derived from peer model
Peer
UNI
Slide 62
Overlay Model
?
Black Box for
IP networks

Two independent control planes isolated from each other
 The IP/ MPLS routing, topology distribution, and signaling
protocols are independent of the ones at the Optical Layer

Routers are clients of optical domain
 The Optical Networks provides wavelength path to the
electronic clients(IP routers, ATM switches)

Optical topology invisible to routers (Information Hiding)

Conceptually similar to IP over ATM model

Standard network interfaces are required such as UNI and NNI
Slide 63
Slide 64
Overlay Model
IP Border Router
UNI
Border OXC
IP Border Router
UNI
IP Border Router
Border OXC
Core OXC
UNI
Border OXC
IP Border Router UNI
UNI
IP Border Router
Client/Server Model
Slide 65
From
To
Avail. BW
A
E
500Mbps
IP (Logical) Routing
A
E
Physical (RWA) Routing
A
2 per fiber, 1Gbps each
D
Router
Router
From
To
Req. BW
A
E
500Mbps
OXC
OXC
OXC
B
OXC
OXC
Router
C
Router
E
Router
Slide 66
From
To
Avail. BW
A
E
500Mbps
C
D
0
IP (Logical) Routing
C
A
D
E
Physical (RWA) Routing
A
2 per fiber, 1Gbps each
D
Router
Router
From
To
Req. BW
A
E
500Mbps
C
D
1Gbps
OXC
OXC
OXC
B
OXC
OXC
Router
C
Router
E
Router
Slide 67
From
To
Avail. BW
A
E
500Mbps
C
D
0
A
B
250Mpbs
IP (Logical) Routing
B
A
C
D
E
Physical (RWA) Routing
A
2 per fiber, 1Gbps each
D
Router
Router
From
To
Req. BW
A
E
500Mbps
C
D
1Gbps
A
B
750Mbps
OXC
OXC
OXC
B
OXC
OXC
Router
C
Router
E
Router
Slide 68
From
To
Avail. BW
A
E
500Mbps
C
D
0
A
B
250Mpbs
B
D
200Mbps
IP (Logical) Routing
B
A
C
D
E
Physical (RWA) Routing
A
2 per fiber, 1Gbps each
D
Router
Router
From
To
Req. BW
A
E
500Mbps
C
D
1Gbps
A
B
750Mbps
B
D
800Mbps
OXC
OXC
OXC
B
OXC
OXC
Router
C
Router
E
Router
Slide 69
From
To
Avail. BW
A
E
500Mbps
C
D
0
A
B
250Mpbs
B
D
200Mbps
A
E
0
IP (Logical) Routing
B
A
C
D
E
Physical (RWA) Routing
A
2 per fiber, 1Gbps each
D
Router
Router
From
To
Req. BW
A
E
500Mbps
C
D
1Gbps
A
B
750Mbps
B
D
800Mbps
A
E
500Mbps
OXC
OXC
OXC
B
OXC
OXC
Router
C
Router
E
Router
Slide 70
Slide 71
Peer Model
Routers and optical switches
function as peers
Uniform and Unified
control plane
Integration
Continuity
Slide 72
The Peer model (IP-over-WDM)
> The IP and optical network are treated together as a single
integrated network managed and traffic engineered in a
unified manner.
 Thus, from a routing and signaling point of view, there is
no distinction between the UNI, the NNI, and any other
router-to-router interfaces.
> The OXCs are treated just like any other router as far as
the control plane is concerned.
> The IP/MPLS layers act as peers of the optical transport
network, such that a single routing protocol instance runs
over both the IP/MPLS and optical domains.
Slide 73
Slide 74
Which signaling technique for all-optical
WDM core networks ?

In-band signaling :
 The header is modulated at a low bit rate and carried on
channel i
 The payload is modulated at a high bit rate and carried on
channel i
 The header and the payload transmissions are separated
by a guard time
 Optical Burst Switching is based on in-band signaling

Out-of-band signaling :
 The header of each packet is carried on a separate optical
signaling channel
 This signaling channel may be either unique 0 for all the
optical data channels (option #1)
 Or specific signaling channels *k are associated to
subsets of data channels {i} (option #2)
 Out-of-band signaling is well suited to slot synchronized
Slide 75
Option #1
0
i
*0
Option #2
i
0
i
Slide 76
How to share the common out-of-band
signaling channels ?
 Time
Division Multiple Access (TDMA)
 Advantage : simple to implement
 Drawbacks :
Too rigid for bursty traffic
Not scalable
Decay in the arrival time of the headers
associated to parallel data packets
 Code Division Multiple Access (CDMA)
 Advantage : The headers associated to parallel
packets arrive at the same time
 Drawback:
Relatively expensive to implement
Slide 77
Sub-carrier
modulation (SCM)
 Advantage :
Cost-effective
Scalable
The headers associated to
parallel packets arrive at the
same time
Slide 78
Principle of sub-carrier modulation
(1)
Optical power
f0

NRZ data
Input current
Microwave oscillator
"1"
f0
"0"
f0
"1"
Slide 79
Principle of sub-carrier modulation
(2)
Microwave carriers between 10 MHz and 10 GHz
Header of IP packet #1

f1
RF/microwave
bandpass filter
BPF
Microwave oscillator





Header of IP packet #2
Optical carriers around 100 THz
f2
BPF

Microwave oscillator
Header of IP packet #2

f3
BPF
Microwave oscillator
Header of IP packet #4
f4
BPF
Microwave oscillator
Slide 80