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IP-optical Integration

Peter Sjdin

KTH TSLab, Kista, Sweden

psj@kth.se

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Layered Communication Model

Modular design with well-defined interfaces

Independent layers

Duplicated functionality

Connection management

Error control

Flow control Quality of service

Each layer requires its ownmanagement

From B. A. Forouzan: Data Communications and Networking, 4th ed, McGraw-Hill

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End-to-end Arguments

End-to-end arguments in system design, by J.H.Saltzer, D.P. Reed and D.D. Clark, 1981.

A function or service should be carried out within anetwork layer only if

it is needed by all clients of that layer,

and it can be completely implemented in that layer. Result is that protocol operations shift towards the

network end-points

Dumb network, smart terminals

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SONET/SDH Networks

TDM circuit switching

Packet switching overSONET/SDH

ATM infrastructure ontop

IP routers connected

to ATM switches

Regenerationof optical signal

Combination of

multiple signalson a path

Adding signals into

(dropping signalsfrom) a path

From B. A. Forouzan: Data Communications and Networking, 3rd ed, McGraw-Hill

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SONET/SDH Control

Three individual control planes

IP, ATM and SDH

Redundancy between IP andATM in particular

Both are packet (cell)switched networks

Routing, addressing Flow control, error control

Fragmentation and reassembly

SONET/SDH

Fiber Optics

IP

ATM

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ATM, MPLS Switching and IP Routing

Simplify by introducing yet another protocol layer!

MPLS (Multi-Protocol Label Switching)

Unites IP and ATM

Use control information from IP to set up MPLS LSPs(Label Switch Paths)

IP routing, RSVP, etc

LSP

IP pktl=xIP pkt

l=yIP pkt

l=zIP pkt

l=vIP pkt

IP pkt

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Control of SONET/SDH Networks

Replace ATM control by MPLS

SONET/SDH

Fiber Optics

ATM data plane

IP

MPLS

SONET/SDH

Fiber Optics

IP

ATM

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WDMWavelength Division

Multiplexing

Cost-efficient solution compared to SONET/SDH

Singlewavelength

Multi-wavelength

Singlewavelength

Mult iplexer Demult iplexer

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WDM System

Add/drop and cross-connectconfiguration

M u l t i p l e x e r D e m u l t i p l e x e r

Nx N

T r a n s p o n d e r s

T r a n s p o n d e r s

A d d ed w a v el en g t h s

D r o p p ed w a v el en g t h s

Transponders

Combine receive/transmit ondifferent wavelengths

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Control of WDM Networks

SDH/SONET are for setting up synchronous circuits

IP control protocols (routing protocols, RSVP, etc) are

for controlling packet switches Manual configuration and/or proprietary control

protocols for controlling WDM networks

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Enters Generalized MPLS (GMPLS)

MPLS switching generalized to control different kinds of switching

Packet switching

TDM

Time slots

TSI switches between time slots

Cross Connects (space division multiplexing)

Switches between ports (fibers)

Wavelength (lambda) switching Switches between wavelengths

IETF MPLS and CCAMP (Common Control and Measurement Plane) working groups

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GMPLS Rationale

Unified control plane for IP over optical networks

SONET/SDH

Fiber Optics

ATM data plane

IP

MPLS

Fiber Optics

IP

GMPLS

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Generalized Label Request

Generalized labels is superset of MPLS labels

Wavelength, time slot, ATM VCI/VPI, generic MPLS labels (shim),

Switching type Payload identifierLSP encoding type

Type of label

Packet

SONET/SDH

Wavelength

Swit ch capabilities

Packet switch

Time slot switch

Wavelength switch

Fiber (port) switch

Virtual Tributary

ATM

Ethernet

Type of payload

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Hierarchical LSPs

LSPs can be organized into hierarchies

From a (link state) routing point of view, each LSP is a link

Link bundling allows several LSPs with similar attributes to be treated as a single link

Fiber LSPWavelength LSP

Time slot LSP

Packet LSP

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Using IP to Control Cross Connects

BGP, RSVP, etc. are forcontrolling routers

Next hop routing based on IP

addresses

An optical cross connectswitches lightpaths, not packets

Still, it needs to appear as a

router IP addresses

Wavelengths, fibers, are links

Nx N

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GMPLS over Ethernet

MPLS treats an Ethernet as a single link

One hop in an LSP

Even if the LSP goes through multiple Ethernet switches But with GMPLS, couldnt we control Ethernet switches

as well?

In analogy with how we deal with optical switches Yes, but:

We need to decide what is a generalised label in Ethernet

Ethernet switches need to recognize and switch betweengeneralised labels

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Conclusions

Large benefit from an operational point of view if we canuse IP for controlling the network Even if it is not a packet switched network

GMPLS is emerging as an important way of controllingoptical networks from IP Requires a generalization of the label concept from MPLS to be

applicable to non-packet networks Optical switches need to appear as IP routers, even

though they do not forward IP packets

If we want to use GMPLS to control different switches,

we need to define new generalized switching models For Ethernet, for instance

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Thank You For Listening!