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IP over …… ATM … SDH … DWDM

Mario BaldiPolitecnico di Torino

(Technical University of Torino)http://staff.polito.it/mario.baldi

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Nota di CopyrightThis set of transparencies, hereinafter referred to as slides, is protected by copyright laws and provisions of International Treaties. The title and copyright regarding the slides (including, but not limited to, each and every image, photography, animation, video, audio, music and text) are property of the authors specified on page 1.The slides may be reproduced and used freely by research institutes, schools and Universities for non-profit, institutional purposes. In such cases, no authorization is requested.Any total or partial use or reproduction (including, but not limited to, reproduction on magnetic media, computer networks, and printed reproduction) is forbidden, unless explicitly authorized by the authors by means of written license.Information included in these slides is deemed as accurate at the date of publication. Such information is supplied for merely educational purposes and may not be used in designing systems, products, networks, etc. In any case, these slides are subject to changes without any previous notice. The authors do not assume any responsibility for the contents of these slides (including, but not limited to, accuracy, completeness, enforceability, updated-ness of information hereinafter provided). In any case, accordance with information hereinafter included must not be declared.In any case, this copyright notice must never be removed and must be reported even in partial uses.

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IP Everywhere. Anything else?

Wide AreaWide Area

??

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Which is the Best Interconnection Topology?

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Even if You Know It, You Know It only Now!

It can change on a monthly basedifferent customersdifferent customer needs

It can change on a weekly baseevents

It can change on a daily basebusiness users during week-days, residential users during the week-end

It can change on a hourly basebusiness hoursevening entertainment

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IP over PhotonsRouters are connected by optical fibers

The optical signal transmitted by a router is received by the other

Layer 2 framing as in any synchronous transmission

PPPIEEE 802.3

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Pros and ConsNo overhead

Physical connections: no reconfigurability

One interface per connection

No standard management infrastructure

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IP over Dense Wavelength Division Multiplexing (DWDM)

Many transmissions with different wavelengths (colors) on the same fiberMultiplies fiber capacityOptical switches with wavelength routingLayer 2 framing: PPP

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Pros and ConsVery high capacity

Virtual connections with optical routing

No standard management infrastructure

Static multiplexing

Reconfiguration Flexibility?

One interface for many connections?How about IP addresses?

One per physical interface?

One per wavelength?

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IP over SONET/SDH(Synchronous Optical NETworkSynchronous Digital Hierarchy)

Physical layer framingCross connectFine allocation granularityManagement frameworkLayer 2 framing: PPP

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Transmission Hierarchy

PDH Hierarchy

USA

T1 - DS1 1.544 Mbps

T3 - DS3 44.736 Mbps

SDH Hierarchy

USA: SONET Europe: SDH

OC-3c / STS-3c 155.52 Mbps

STM-1155.52 Mbps

STM-4622.08 Mbps

OC-12c / STS-12c 622.08 Mbps

STM-122.4 Gbps

OC-48c / STS-48c 2.4 Gbps

OC-1c / STS-1c 51.84 Mbps

Europe

E1 2.048 Mbps

E3 34.368 Mbps

E4 139.26 Mbps

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Physical ArchitectureSection: fiber optics trunk between transceiversLine: sequence of sections between devices which operates on the framePath: end-to-end leased line

T

SON

ET/S

DH

M

UXT

T

Add

/Dro

p M

UX

SON

ET/S

DH

M

UX

T

T

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SectionSection SectionSection SectionSection SectionSectionLineLine LineLine

PathPath

Repeater Repeater

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Protocol ArchitecturePhotonic Layer: fiber, laserSection Layer: frames, OAM (Operation Administration and Management)Line Layer: synchronization, multiplexing, switching, OAMPath Layer: end-to-end data (bytes) transfer

Photonic Layer

Section Layer

Line Layer

Path Layer

Frame

Photonic Layer

Section Layer

Photonic Layer

Section Layer

Line Layer

Photonic Layer

Section Layer

Line Layer

Path Layer

Higher Layer Higher Layer

Light

STS-N / STM-N Block

Envelope

Terminal TerminalRepeater Multiplexer

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Frame FormatSTS-1: 810 octets every 125 μs 51.84 Mbps

A1 A2 C1 J1

B1

D1

H1

B2

D4

D7

D10

Z1

D2

H2

K1

D5

D8

D11

Z2

F1

D3

H3

K2

D6

D9

D12

E2

B3

C2

G1

E1

F2

H4

Z3

Z4

Z5

Payload Payload

90 octets

9 oc

tets

0 μs

125 μsSection Overhead Line Overhead Path Overhead

Synchronous Payload Environment (SPE) 87 octets3 octets

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Pros and ConsStandard OAM architecture

Virtual connections

One interface per connection

Static multiplexing

Limited reconfiguration flexibility

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IP over ATM(Asynchronous Transfer Mode)

Cell switchingflexible multiplexing

Semi-permanent and switched virtual connectionsLayer 2 protocol

no need for layer 2 framing

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Pros and ConsVirtual connections

Multiple connections per interface

Total reconfiguration flexibility

Support for other services (e.g., frame relay)

Flexible multiplexing

High protocol overhead (more than 10%)

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IP over FR(Frame Relay)

Frame switchingflexible multiplexing

Semi-permanent virtual connectionsLayer 2 protocol

no need for layer 2 framing

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Pros and ConsVirtual connections

Multiple connections per interface

Large installed base

No Quality of Service Guarantees

Why is another packet switching layer needed?

Because IP lacks traffic engineering capabilityBecause IP lacks traffic engineering capability

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MPLS(Multi-Protocol Label Switching)

Frame switchingflexible multiplexing

Dynamic virtual connections (label switched paths)Layer 2 protocol tightly integrated with layer 3

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Pros and ConsVirtual connections

Multiple connections per interface

One control plane: no “IP over”

No Quality of Service Guarantees