Agenda

1
Agenda

• Protocol Layering
• Why Simplify?
• First Steps MP?S
• Emerging Optical Switching Technologies

2
Protocol Layering
Application
We know from experience that we can't run
applications directly over media Solution
Protocol Layering
FIBER
3
Protocol Layering
Application

• Applications include
• Leased lines
• National telephone services

SDH / SONET
Fiber
4
Protocol Layering
Application
IP
Internet services emerge
SDH / SONET
Fiber
5
Protocol Layering
Application
IP
IP
PoA
PoS
ATM

• ATM is introduced as
• Traffic Engineering layer in the Internet
• Native service

SDH / SONET
Fiber
PoA - Packet over ATM PoW - Packet over WDM GE -
Gigabit Ethernet PoS - Packet over SDH
6
Protocol Layering
Application
IP
IP
PoA
ATM
Wavelength Division Multiplexing appears as a
mechanism to increase capacity on a fibre
SDH / SONET
WDM
Fiber
7
Protocol Layering
Native Ethernet services appear to be a
cost-effective alternative, but need SONET/SDH
framing
Application
IP
IP
PoA
PoS
ATM
GE
SDH / SONET
WDM
Fiber
8
Protocol Layering
MultiProtocol Label Switching appears as
alternative to ATM Traffic Engineering
Application
IP
IP
PoA
ATM
GE
MPLS
PoS
PoS
SDH / SONET
WDM
Fiber
9
Protocol Layering
Digital Wrapper appears as an early "SONET-lite"
technology for direct Packet-over-Wavelengths
Application
IP
IP
PoA
ATM
GE
MPLS
PoS
SDH / SONET
PoW
Digital Wrapper
WDM
Fiber
10
Data Transfer Over Frame-based Networks
File
TCP
IP
Frame (Ethernet, FR, PPP)
11
Data Transfer Over Cell-based Networks
File
TCP
IP
Adaptation
ATM Cells
12
Agenda

• Protocol Layering
• Why Simplify?
• First Steps MP?S
• Emerging Optical Switching Technologies
• Optical Packet Switching
• Optical Burst Switching

13
What do these layers do?
IP

• IP is the service
• Addressing
• Routing
• ATM provides Traffic Engineering
• SONET/SDH provides
• Provisioning control
• Service restoration
• OAM statistics
• Low error rate
• WDM provides capacity

Over ATM
Over SONET/SDH
Over DWDM
14
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
15
An IP RouterThe Data Plane
Control Processor
OUTPUTS
Packet Backplane
Outbound Packet
INPUT
Inbound Packet
16
An IP RouterThe Control Plane
Routing Table
Router Applications
eg. OSPF, ISIS, BGP
Control Processor
Packet Backplane
Routing Updates
17
Bandwidth Bottlenecks

• Routing Protocols Create A Single "Shortest Path"

C1
C3
C2
"Longer" paths become under-utilised
Path for C1 ltgt C3
Path for C2 ltgt C3
18
Engineering-Out The Bottlenecks

• ATM Switches Enable Traffic Engineering

C1
C3
C2
PVC C1 ltgt C3
PVC C2 ltgt C3
19
What Is MPLS?A Software Upgrade To Existing
Routers

• MPLSa software upgrade?

Router
S/W
LSR
20
What Is MPLS?A Software Upgrade To ATM Switches

• MPLSa software upgrade?

ATM Switch
ATM LSR
S/W
21
ROUTE AT EDGE, SWITCH IN CORE
IP
IP
IP Forwarding
IP Forwarding
LABEL SWITCHING
22
MPLS HOW DOES IT WORK
TIME
TIME
23
Forwarding Equivalence Classes
LSR
LSR
LER
LER
LSP
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

24
MPLS BUILT ON STANDARD IP
47.1
1
2
1
3
2
1
47.2
3
47.3
2

• Destination based forwarding tables as built by
  OSPF, IS-IS, RIP, etc.

25
MPLS Takes Over

• MPLS LSRs Enable Traffic Engineering

C1
C3
C2
LSP C1 ltgt C3
LSP C2 ltgt C3
26
MPLS Path CreationQuality 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)
27
Typical IP Backbone (Late 1990s)

• Data piggybacked over traditional voice/TDM
  transport

28
IP/PPP/HDLC packet mappings to SONET frames
(OC-48, OC-192)
Gigabit IP Router
Demux
Mux
Wavelength laser transponders
29
(No Transcript)
30
Why So Many Layers?

• Router
• Packet switching
• Multiplexing and statistical gain
• Any-to-any connections
• Restoration (several seconds)
• ATM/Frame switches
• Hardware forwarding
• Traffic engineering
• Restoration (sub-second)

• MUX
• Speed match router/ switch interfaces to
  transmission network
• SONET/SDH
• Time division multiplexing (TDM)
• Fault isolation
• Restoration (50mSeconds)
• DWDM
• Raw bandwidth
• Defer new construction

• Result
• More vendor integration
• Multiple NM Systems
• Increased capital and operational costs

31
IP Backbone Evolution
Core Router (IP/MPLS)

• MUX becomes redundant
• IP trunk requirements reach SDH aggregate
  levels
• Next generation routers include high speed
  SONET/SDH interfaces

FR/ATM Switch
MUX
SONET/SDH
DWDM (Maybe)
32
Collapsing Into Two Layers
IP Service (Routers)
Optical Core
Optical Transport (OXCs, WDMs, SONET ?)
33
WDM Network Architecture
34
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.
35
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
36
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.
37
(No Transcript)
38
(No Transcript)
39
Node B Nodal Degree of 2, 100?/fiber 2X2X100?
ports to add/drop
Node B
Node A
Node C
40
IP over Optical Network Architectural Models
41
We Need Optical Traffic Engineering

• Classically the OXC "control plane" is based on
  the NMS
• 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

42
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

43
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

44
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"

45
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 at the
  outbound port
• Wavelength translation is expensive
• If 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?

46
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

47
The Label Information Base
Connection Table
In (port,Label)
Out (port, Label, Operation)
Port 1
Port 3
Port 2
Port 4

• Labelled packet arrives at Port 1, with Label
  value "5"
• LIB entry indicates switch to Port 4, and swap
  label to value "7"

48
The Optical Connection TableCase 1a No
wavelength translation
Connection Table
In (port,Lambda)
Out (port, Lambda)
Port 1
Port 3
?2
Port 2
Port 4
?2

• Channel 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

49
The Optical Connection TableCase 1b No
wavelength translation
Connection Table
In (port,Lambda)
Out (port, Lambda)
Port 1
Port 3
?3
Port 2
Port 4
?3

• Channel 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

50
The Optical Connection TableCase 2 Wavelength
translation
Connection Table
In (port,Lambda)
Out (port, Lambda)
Port 1
Port 3
Port 2
Port 4
?3
?1

• Channel 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

51
New Concept MP Lambda SToday NMS Configuration

• Each optical trail is set up in Service Provider
  NOC

OADM
OADM
OXC
OXC
OXC
OXC
52
New Concept MP Lambda SToday NMS Configuration

• Each optical trail is set up in Service Provider
  NOC

OADM
OADM
OXC
OXC
OXC
OXC
53
New Concept MP Lambda SToday NMS Configuration

• Each optical trail is set up in Service Provider
  NOC

OADM
OADM
OXC
OXC
OXC
OXC
54
New Concept MP Lambda SToday NMS Configuration

• Each optical trail is set up in Service Provider
  NOC

OADM
OADM
OXC
OXC
OXC
OXC
55
New Concept MP Lambda SToday NMS Configuration

• Final stage is to enable connection in CPE
  devices
• eg. Manual Traffic Engineering of LSP to OCT

OADM
OADM
OXC
OXC
OXC
OXC
56
New Concept MP Lambda SOXCs take part in routing

• Enhance OSPF-TE and ISIS-TE to include
  optical-specific metrics and parameters

OADM
OADM
OXC
OXC
OXC
OXC
Optically-enhanced routing protocol exchange
57
New Concept MP Lambda SCPE uses Optical UNI
Signalling

• Must create an Optical UNI spec.

OADM
OADM
OXC
OXC
OXC
OXC
Optical UNI signalling protocol
58
New Concept MP Lambda SOXCs create optical trail

• May be based on signalled constraints, and may
  include policy-driven permission

OADM
OADM
OXC
OXC
OXC
OXC
NMS notification, and/or policy exchange process
59
LSP to OCT MappingGranularity Issues
OCT 1
LSP 1
LSP 1
OCT 2
LSP 2
LSP 2
Lambda Switch
Lambda Switch
W D M
W D M
LSR
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

60
LSP to OCT MappingSolution LSP aggregation at
LSR
OCT 1
LSP 1
LSP 1
...
...
LSP n
LSP n
Lambda Switch
Lambda Switch
W D M
W D M
LSR
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

61
Operational ApproachesOverlay 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

?
62
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

63
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

64
(No Transcript)
65
Overlay Model
IP Border Router
UNI
Border OXC
UNI
IP Border Router
IP Border Router
Core OXC
Border OXC
UNI
Border OXC
UNI
IP Border Router
UNI
IP Border Router
Client/Server Model
66
IP (Logical) Routing
A
E
Physical (RWA) Routing 2?? per fiber, 1Gbps each
A
D
Router
Router
OXC
OXC
OXC
B
OXC
OXC
Router
C
E
Router
Router
67
IP (Logical) Routing
C
A
D
E
Physical (RWA) Routing 2?? per fiber, 1Gbps each
A
D
Router
Router
OXC
OXC
OXC
B
OXC
OXC
Router
C
E
Router
Router
68
IP (Logical) Routing
B
C
A
D
E
Physical (RWA) Routing 2?? per fiber, 1Gbps each
A
D
Router
Router
OXC
OXC
OXC
B
OXC
OXC
Router
C
E
Router
Router
69
IP (Logical) Routing
B
C
A
D
E
Physical (RWA) Routing 2?? per fiber, 1Gbps each
A
D
Router
Router
OXC
OXC
OXC
B
OXC
OXC
Router
C
E
Router
Router
70
IP (Logical) Routing
B
C
A
D
E
Physical (RWA) Routing 2?? per fiber, 1Gbps each
A
D
Router
Router
OXC
OXC
OXC
B
OXC
OXC
Router
C
E
Router
Router
71
(No Transcript)
72
Peer Model
Routers and optical switches function as peers
Uniform and Unified control plane
Integration Continuity
73
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.

74
(No Transcript)
75
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 li
• The payload is modulated at a high bit rate and
  carried on channel li
• 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 l0
  for all the optical data channels (option 1)
• Or specific signaling channels lk are
  associated to subsets of data channels li
  (option 2)
• Out-of-band signaling is well suited to slot
  synchronized networks

76
l0
Option 1
li

l0
li
l0
Option 2
li
77
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

78

• Sub-carrier modulation (SCM)
• Advantage
• Cost-effective
• Scalable
• The headers associated to parallel packets arrive
  at the same time

79
Principle of sub-carrier modulation (1)
80
Principle of sub-carrier modulation (2)