Slide 1 Agenda Protocol Layering Why Simplify? First Steps: MP S Emerging Optical Switching...

AgendaAgenda

Protocol Layering Why Simplify? First Steps: MPS Emerging Optical Switching Technologies:

FIBER

Application

Protocol LayeringProtocol Layering

We know from experience that we can't run applications

directly over media

Solution: Protocol Layering

We know from experience that we can't run applications

directly over media

Solution: Protocol Layering

Fiber

Application


Applications include…• Leased lines• National telephone services

Applications include…• Leased lines• National telephone services

SDH / SONET

Fiber

Application


Internet services emergeInternet services emergeSDH / SONET

IP

Fiber

Application


SDH / SONET

IP

PoA

IP

ATM

ATM is introduced as…• Traffic Engineering layer in

the Internet• Native service

ATM is introduced as…• Traffic Engineering layer in

the Internet• Native service

PoA - Packet over ATM PoW - Packet over WDMGE - Gigabit Ethernet PoS - Packet over SDH

PoS

Fiber

Application


SDH / SONET

IP

PoA

IP

ATM Wavelength Division Multiplexing appears as a mechanism to increase

capacity on a fibre

Wavelength Division Multiplexing appears as a mechanism to increase

capacity on a fibre

WDM

Fiber

Application


SDH / SONET

IP

PoA

IP

ATM

Native Ethernet services appear to be a cost-

effective alternative, but need SONET/SDH framing

Native Ethernet services appear to be a cost-

effective alternative, but need SONET/SDH framing

WDM

GE

PoS

Fiber

Application


SDH / SONET

IP

PoA

IP

ATM

MultiProtocol Label Switching appears as

alternative to ATM Traffic Engineering

MultiProtocol Label Switching appears as

alternative to ATM Traffic Engineering

WDM

GEPoS PoS

MPLS

Fiber

Application


SDH / SONET

IP

PoA

IP

ATM

Digital Wrapper appears as an early "SONET-lite" technology for direct

Packet-over-Wavelengths

Digital Wrapper appears as an early "SONET-lite" technology for direct

Packet-over-Wavelengths

WDM

GEPoS

Digital Wrapper

PoW

MPLS

Data Transfer Over Frame-Data Transfer Over Frame-based Networksbased Networks

File

TCP

IP

Frame(Ethernet, FR, PPP)

Data Transfer Over Cell-Data Transfer Over Cell-based Networksbased Networks

File

TCP

IP

Adaptation

ATM Cells

AgendaAgenda

Protocol Layering Why Simplify? First Steps: MPS Emerging Optical Switching Technologies:

Optical Packet Switching Optical Burst Switching

What do these layers do?What do these layers do?

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

SONETSONET

SDHSDH

WDMWDM

IPIP

OverATMOverATM

OverSONET/SDH

OverSONET/SDH

OverDWDMOver

DWDM

Control Plane v Data PlaneControl Plane v Data Plane

The data plane actually carries the information while the control plane sets up pathways through the data plane

The data plane actually carries the information while the control plane sets up pathways through the data plane

MPLS LSRs and MPS OXCs both solve performance scalability problem by decoupling control and data planes

MPLS LSRs and MPS OXCs both solve performance scalability problem by decoupling control and data planes

An IP Router:An IP Router:The Data PlaneThe Data Plane

INPUT

Packet BackplanePacket Backplane

OUTPUTS

Control ProcessorControl Processor

Inbound PacketInbound Packet

Outbound PacketOutbound Packet

An IP Router:An IP Router:The Control PlaneThe Control Plane

Packet BackplanePacket Backplane

Control ProcessorControl Processor

Routing TableRouting Table

Routing Updates

Router ApplicationsRouter Applicationseg. OSPF, ISIS, BGP

C3

C1

C2

Path for C1 <> C3

Path for C2 <> C3

"Longer" paths become under-

utilised

"Longer" paths become under-

utilised

Bandwidth Bottlenecks

Routing Protocols Create A Single "Shortest Path"

C3

C1

C2

PVC C1 <> C3PVC C2 <> C3

Engineering-Out The Bottlenecks

ATM Switches Enable Traffic Engineering

What Is MPLS?What Is MPLS?A Software Upgrade To Existing RoutersA Software Upgrade To Existing Routers

MPLS…a software upgrade?

+ =

Router S/W LSR

What Is MPLS?What Is MPLS?A Software Upgrade To ATM SwitchesA Software Upgrade To ATM Switches

MPLS…a software upgrade?

+ =ATM

SwitchS/W

ATMLSR

ROUTE AT EDGE, SWITCH IN ROUTE AT EDGE, SWITCH IN CORECORE

IP ForwardingLABEL SWITCHINGIP Forwarding

IP IP #L1 IP #L2 IP #L3 IP

MPLS: HOW DOES IT MPLS: HOW DOES IT WORK WORK

UDP-Hello

UDP-Hello

TCP-open

TIME

TIME

Label requestIP

Label mapping#L2

Initialization(s)

Forwarding Equivalence ClassesForwarding Equivalence Classes

• 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

Packets are destined for different address prefixes, but can bemapped to common pathPackets are destined for different address prefixes, but can bemapped to common path

IP1

IP2

IP1

IP2

LSRLSRLER LER

LSP

IP1 #L1

IP2 #L1

IP1 #L2

IP2 #L2

IP1 #L3

IP2 #L3

MPLS BUILT ON STANDARD IPMPLS BUILT ON STANDARD IP

47.1

47.247.3

Dest Out

47.1 147.2 2

47.3 3

1

23

Dest Out

47.1 147.2 2

47.3 3

Dest Out

47.1 147.2 2

47.3 3

1

23

1

2

3

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

C3

C1

C2

LSP C1 <> C3

LSP C2 <> C3

MPLS Takes OverMPLS Takes Over

MPLS LSRs Enable Traffic Engineering

DS

Low delay (preferred for VoIP traffic)

High bandwidth (preferred for FTP)

MPLS Path Creation:MPLS Path Creation:Quality of Service RefinementsQuality of Service Refinements

Source device (S) determines the type of path on the basis of the data

Typical IP Backbone (Late Typical IP Backbone (Late 1990’s)1990’s)

Data piggybacked over traditional voice/TDM transport

SONET/SDHDCS

SONET/SDHDCS

CoreRouter

ATMSwitch

MUX

SONET/SDHADM

CoreRouter

ATMSwitch

MUX

CoreRouter

ATMSwitch

MUX

CoreRouter

ATMSwitch

MUX

SONET/SDHADM

SONET/SDHADM

SONET/SDHADM

Point-to-point DWDM links (Linear or ring

SONET topologies)

SO

NE

TS

ON

ET

IP routing protocols (OSPF, BGP)

Gigabit IP Router

Mux Demux

Wavelength laser transponders

IP/PPP/HDLC packet mappings to SONET

frames (OC-48, OC-192)

Why So Many Layers?Why So Many Layers? RouterRouter

Packet switchingPacket switching Multiplexing and statistical Multiplexing and statistical

gaingain Any-to-any connectionsAny-to-any connections Restoration (several Restoration (several

seconds)seconds) ATM/Frame switchesATM/Frame switches

Hardware forwardingHardware forwarding Traffic engineeringTraffic engineering Restoration (sub-second)Restoration (sub-second)

MUXMUX Speed match router/ Speed match router/

switch interfaces to switch interfaces to transmission networktransmission network

SONET/SDHSONET/SDH Time division Time division

multiplexing (TDM)multiplexing (TDM) Fault isolationFault isolation Restoration Restoration

(50mSeconds)(50mSeconds) DWDMDWDM

Raw bandwidthRaw bandwidth Defer new constructionDefer new construction

ResultResult More vendor integrationMore vendor integration Multiple NM SystemsMultiple NM Systems Increased capital and operational costsIncreased capital and operational costs

SONET/SDH

DWDM

CoreRouter(IP/MPLS)

IP Backbone EvolutionIP Backbone Evolution

MUX becomes redundant

IP trunk requirements reach SDH aggregate levels

Next generation routers include high speed SONET/SDH interfaces

CoreRouter(IP/MPLS)

MUX

SONET/SDH

DWDM(Maybe)

FR/ATM Switch

Collapsing Into Two LayersCollapsing Into Two Layers

Optical Transport(OXCs, WDMs, SONET ?)

Optical Core

IP Service (Routers)

WDM Network ArchitectureWDM Network Architecture

WDMMux/demux

WDMMux/demux

OA

Transponder

Core Router

STM-16STM-64

POS

O/EO

Transponder

Core Router

O/EO

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.

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.

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

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

The ProblemThe 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.

OXC

IP/MPLS module

Tx’sRx’s

(IP-aware)OXC

CONTROLLER

Local Add / Drop

Transponder Interface


OXC

IP/MPLS module

Tx’sRx’s

(IP-aware)OXC

CONTROLLER

Local Add / Drop



OXC

IP/MPLS module

Tx’sRx’s

(IP-aware)OXC

CONTROLLER

Local Add / Drop



Node A

Node B

Node C

Node B: Nodal Degree of 2, 100/fiber 2X2X100 ports to add/drop

IP over Optical Network Architectural Models

IP over Optical Network Architectural Models

We Need Optical Traffic We Need Optical Traffic EngineeringEngineering

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

Solution: Optical SwitchingSolution: 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

Lambda Switching ObjectivesLambda 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

How Do We Label a Lambda?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"

Concepts in Lambda Concepts in Lambda SwitchingSwitching

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?

Recap: MP Recap: MP LabelLabel S 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

The Label Information BaseThe Label Information Base

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

value "7"

Connection TableIn

(port,Label)Out

(port, Label, Operation)

(1, 5)

(1, 3)

(1, 17)

(2, 3)

(4, 7, Swap)

(4, 27, Swap)

(4, 123, Swap)

(3, 17, Push)

Port 1

Port 2

Port 3

Port 4

5

7

The Optical Connection TableThe Optical Connection TableCase 1a: No wavelength translationCase 1a: No wavelength translation

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

Connection TableIn

(port,Lambda)Out

(port, Lambda)

(1, 2)

(1, 3)

(1, 1)

(2, 1)

(4, 2)

(4, 3)

(4, 2)

(3, 1)22

22 Port 1

Port 2

Port 3

Port 4

The Optical Connection TableThe Optical Connection TableCase 1b: No wavelength translationCase 1b: No wavelength translation

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

Connection TableIn

(port,Lambda)Out

(port, Lambda)

(1, 2)

(1, 3)

(2, 3)

(2, 1)

(4, 2)

(4, 3)

(4, 1)

(3, 1)33

33 Port 1

Port 2

Port 3

Port 4

The Optical Connection TableThe Optical Connection TableCase 2: Wavelength translationCase 2: Wavelength translation

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

Connection TableIn

(port,Lambda)Out

(port, Lambda)

(1, 2)

(1, 3)

(2, 3)

(2, 1)

(4, 2)

(4, 3)

(4, 1)

(3, 1)33

Port 1

Port 2

Port 3

Port 4 11

New Concept: MP New Concept: MP LambdaLambda S SToday: NMS ConfigurationToday: NMS Configuration

Each optical trail is set up in Service Provider NOC

OXC OXC

OXC

NMS

OADMOADM

OXC


OXC OXC

OXC

NMS

OADMOADM

OXC



OXC OXC

NMS

OADM

OXC

OADM

OXC


New Concept: MP New Concept: MP LambdaLambda SSToday: NMS ConfigurationToday: NMS Configuration

OXC OXC

NMS

OADM

OXC

OADM

OXC



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

OXC OXC

NMS

OADM

OXC

OADM

OXC

New Concept: MP New Concept: MP LambdaLambda S SOXCs take part in routingOXCs take part in routing

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

OXC OXC

OXC

OADM

OXC

NMS

OADM

Optically-enhanced routing protocol exchangeOptically-enhanced routing protocol exchange

New Concept: MP New Concept: MP LambdaLambda S SCPE uses Optical UNI SignallingCPE uses Optical UNI Signalling

Must create an Optical UNI spec.

OXC OXC

OXC

OADM

OXC

NMS

OADM

Optical UNI signalling protocolOptical UNI signalling protocol

New Concept: MP New Concept: MP LambdaLambda S SOXCs create optical trailOXCs create optical trail

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

OXC OXC

NMS

NMS notification, and/or policy exchange processNMS notification, and/or policy exchange process

OXC

OADM

OXC

OADM

LSP to OCT MappingLSP to OCT MappingGranularity IssuesGranularity Issues

LambdaSwitch

LambdaSwitch

WDM

WDM

LSRLSRLSRLSR

LSP #1LSP #1

LSP #2LSP #2

LSP #1LSP #1

LSP #2LSP #2

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%

OCT #1OCT #1

OCT #2OCT #2

LSP to OCT MappingLSP to OCT MappingSolution: LSP aggregation at LSRSolution: LSP aggregation at LSR

LambdaSwitch

LambdaSwitch

WDM

WDM

LSRLSRLSRLSR

LSP #1LSP #1

LSP #nLSP #n

LSP #1LSP #1

LSP #nLSP #n

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

OCT #1OCT #1

... ...

Operational Approaches:Operational Approaches:Overlay and Peer ModelsOverlay 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

?

The Hybrid ModelThe 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 UNI

Peer

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

Overlay ModelOverlay Model

Client/Server Model

Border OXC

Border OXC

Border OXC

Core OXC

IP Border Router

IP Border Router

IP Border Router

IP Border Router

IP Border Router

UNI

UNI

UNIUNI

UNI

Physical (RWA) Routing2 per fiber, 1Gbps each

IP (Logical) Routing

A D

C

B

E

E

OXC

OXC

OXC

OXC

OXC

Router Router

Router

RouterRouter

A

From To Req. BW

A E 500Mbps

From To Avail. BW

A E 500Mbps



A D

C

B

E

E

OXC

OXC

OXC

OXC

OXC

Router Router

Router

RouterRouter

From To Req. BW

A E 500Mbps

C D 1Gbps

From To Avail. BW

A E 500Mbps

C D 0A C

D



A D

C

B

E

E

OXC

OXC

OXC

OXC

OXC

Router Router

Router

RouterRouter

From To Req. BW

A E 500Mbps

C D 1Gbps

A B 750Mbps

From To Avail. BW

A E 500Mbps

C D 0

A B 250Mpbs

A C

D

B



A D

C

B

E

E

OXC

OXC

OXC

OXC

OXC

Router Router

Router

RouterRouter

From To Req. BW

A E 500Mbps

C D 1Gbps

A B 750Mbps

B D 800Mbps

From To Avail. BW

A E 500Mbps

C D 0

A B 250Mpbs

B D 200Mbps

A C

D

B



A D

C

B

E

E

OXC

OXC

OXC

OXC

OXC

Router Router

Router

RouterRouter

From To Req. BW

A E 500Mbps

C D 1Gbps

A B 750Mbps

B D 800Mbps

A E 500Mbps

From To Avail. BW

A E 500Mbps

C D 0

A B 250Mpbs

B D 200Mbps

A E 0

A C

D

B

IntegrationContinuity

Uniform and Unified control plane

Routers and optical switches function as peers

Peer Model

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.

Which signaling technique for all-optical Which signaling technique for all-optical WDM core networks ?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 networks

0

i

Option #1

0

i

i

0

Option #2

*

How to share the common out-of-band How to share the common out-of-band signaling channels ?signaling channels ?

Time Division Multiple Access (TDMA)Advantage : simple to implementDrawbacks :

Too rigid for bursty trafficNot scalableDecay 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

Sub-carrier modulation (SCM)Advantage :

Cost-effectiveScalableThe headers associated to

parallel packets arrive at the same time

Principle of sub-carrier modulation Principle of sub-carrier modulation (1)(1)

NRZ data

Microwave oscillator"1"

"0"

"1"

Optical power

Input current

f0

f0

f0

Principle of sub-carrier modulation Principle of sub-carrier modulation (2)(2)

Header of IP packet #1

Microwave oscillator

f4


f1


f2


f3

Microwave carriers between 10 MHz and 10 GHz

Optical carriers around 100 THz

RF/microwave bandpass filter

BPF

BPF

BPF

BPF




Slide 1 Agenda Protocol Layering Why Simplify? First Steps: MP S Emerging Optical Switching...

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