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Telecommunications & IT Trends

By Dr. Virgilio Gonzalez/ Dr. Ricardo Pineda

For EE5330 / EE4395 /EE4361

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SONET/ SDH

Synchronous Optical Network (SONET) and Synchronous DigitalHierarchy (SDH) are methods standardized by the telephoneindustry, in the late 80s and early 90s, to synchronize andmultiplex high speed TDM channels.

The synchronization is based on the use of very precise frequencysources (atomic clocks) and maintain all the signals aligned. Thereferences signal can be local or derived from the tributary links.

Higher order channels are obtained by simple interleaving of thelower order channels OC1 x3 OC3 x4 OC12 x4 OC48

SONET is used mostly in US/Canada, and the SDH Internationalversion is almost equivalent. STM1OC3; STM4OC12;STM16OC48; etc.

The solution to support tributaries not well synchronized consistson allowing them to float inside the payload area and use thepointers to distinguish them.

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SONET/SDH Rates

STS

LEVEL

NA OC LEVEL ITU STM

LEVEL

LINE

RATEGROSS

NET OF

OVERHEAD

STS-1 OC-1 N/A 51.84 Mbps 49.50 Mbps

STS-3 OC-3 (2016) STM-1 155.52 Mbps 148.60 Mbps

STS-12 OC-12 (8064) STM-4 622.08 Mbps 594.40 Mbps

STS-24 0C-24 N/A 1.24 Gbps 1.19 Gbps

STS-48 OC-48 (32256) STM-16 2.49 Gbps 2.38 Gbps

STS-96 OC-96 STM-32 4.98 Gbps 4.76 Gbps

STS-192 OC-192 (129024) STM-64 9.95 Gbps 9.52 Gbps

STS-768 OC-768 (516,096) STM-256 39.80 Gbps 38.08 Gbps

STS-3072 OC-3072 STM-1024 159.20 Gbps 152.32 Gbps

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Network Technology Conceptual ViewNetwork philosophy structured in 4

levels1. Core networkis common for

all services and mediationdevices, its function is toprovide: Capacity Restoration Flexibility

2. Services are provided mostly by

mediation devices such as: Switches for voice services Routers for IP Servers for Internet Switches for Frame

Relay/ATM3. Metro - Access should provide

integrated access to various

mediation devices (services).4. CPE (Customer Premise

Equipment) belongs to the userbut could be managed by theTelco adding value to theservice already provided

Core Network

Core Network

Mediation Service

Metro - Access

CPE

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Network Structure Model

VoiceGateway

Router

VideoServer

PacketSwitch

PDH/SDH

ATMBackbone

SW

SW

SW

SW

SW

SW

SW

RadioPMP

DSLAM

CMTS(HFC)

OpticalMUX

RadioP2P

RadioP2P

OLT

ATMLink

ATM

Link

ATMLink

ATMlink

PDHlink

ATM

Link

ATMLink

ATMLink

ATMLink

ATMLink

Fib

er

SDS

PSTN

IP

Video

FR

ATM

LP

FRIPPLATM

VoiceATMISDNFRIPPL

CATVIPVoicePL & FRw ith TDM(CBR)

FRVoiceIP

PLVoiceISDN IPCATVFRATM

PLFRATM

VoiceATMIPISDNPL

FR

Without IAD With IAD

Services

PLFR

ATM

VoiceATM

IPISDNPLFR

DWDM /SDH / ATM

CORE

SW

SW

SW

SW

SW

SW

SW

CORE LAST MILEMETROACCESS

SERVICEMEDIATION

CPE

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Carrier Backbone

ADM

ADM

ADM

ADM

DCS

SW

ADM

PL MIA-SEAT

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Point to Point Links (end-to-end Connection)

CORE LAST MILEMETROACCESS

SERVICEMEDIATION

CPE

VoiceGateway

Router

VideoServer

PacketSwitch

PDH/SDH

ATMBackbone

SW

SW

SW

SW

SW

SW

SW

RadioPMP

DSLAM

CMTS(HFC)

OpticalMUX

RadioP2P

RadioP2P

OLT

ATMLink

ATM

Link

ATMLink

ATMlink

PDHlink

ATM

Link

ATMLink

ATMLink

ATMLink

ATMLink

Fib

er

SDS

PSTN

IP

Video

FR

ATM

LP

FRIPPLATM

VoiceATMISDNFRIPPL

CATVIPVoicePL & FRw ith TDM(CBR)

FRVoiceIP

PLVoiceISDN IPCATVFRATM

PLFRATM

VoiceATMIPISDNPL

FR

Without IAD With IAD

Services

PLFR

ATM

VoiceATM

IPISDNPLFR

DWDM /SDH / ATM

CORE

SW

SW

SW

SW

SW

SW

SW

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Type of Networks

Private Networks: ETN (Corporations up to mid 1990s) LAN (Office, Building, SOHO) WAN/MAN (Campus, Branch Interconnection, etc.) FR/ATM/IP Intranet Private Lines: Leased lines among branches, etc.

Public Networks:

PSTN (Public Switched Telephone Network) WAN/MAN (X.25, Frame Relay, Asynchronous Transfer Mode, IP) Internet (WWW)

Virtual Networks VNS VLAN

Extranet VPDN (VPN) MPLS

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Local Area Networks

Created to share resources in computer environments

Grown in capacity from 100s of kbps to 10/100 GbpsUsually are managed by a single entity and has a small geographicreach

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Public vs. Private Networks

Private ATM Sw itch

Workstation

Telephone

Fax

Minicomputer

Private ATM Sw itch

Workstation

Telephone

Fax

Minicomputer

MainframePublic sw itch

Public sw itch

Public sw itch

NNI - Network to Network Interface

Pub UNI - Public User-to-Network Interface

Priv UNI - Private User-to-Network Interface

NNI

NNI

NNI

Pub UNIPub UNI

Pub UNI

Priv UNI

Priv UNI

Priv UNI

Priv UNI

PUBLIC

NETWORK

PRIVATENETWORK

PRIVATENETWORK

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Circuits and Packets

Circuit switching is a method to establish a path across thenetwork reserving exclusively a resource for the whole durationof the transmission. The resource can be a cable, a frequencycarrier, a time slot or a code. Circuit Switched Network

In a packet network each information unit has a header thatcontains all the necessary information required to properly deliverit to the destination. Each intermediate node must decide how to

handle each packet. Connectionless NetworkA virtual circuit uses packets for the transmission. However thedecisions on how to route the packet has been made beforehand.Connection Oriented

NET

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Data Services Network EvolutionIncorporate Internet and Frame Relay into one ATM core networkproviding integrated management/operation

Incorporate MPLS technology to the network providing the ability tobetter manage and operate IP services (dial-up, VPNs, Internet)

Customers would dial to one integrated network for Frame Relay,VPN, Internet

FR/ATM/CLOUDCatalyst

Catalyst

CoreMex

AccessMexEdge RouterAccessMty

Edge Router

STM1 Backbone

STM1

ATM

Trunk

STM1 STM1

STM1

ATM

Trunk

STM1

ATM

Trunk

STM1

ATM

Trunk

Catalyst

Catalyst

WorldNet - Internet

Dial-up

Dial-up

WEB / Mail Servers

Services Control Logic

INTERNET

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SONET / SDH Protection

The topology of SONET creates a ring connecting

different nodes. The ring is occupied at 50%SONET SDH framing includes constant monitoring ofthe links between devices.

In case of a failure the signal is redirected in the

opposite ring direction until it reaches its originaldestination.

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Restoration in IP Based Networks

IP based networks only use optical links in a point to point basis.

All the IP packets gets converted back to electronic domain andare processed in the routers.

Routers constantly exchange information regarding their routingtables, link status and cost metrics.

In case of a failure the routers will update their tables and will

compute again the best available path for each destination.There is no restoration time guarantee but the system is moreflexible

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Data Services

Private Line

ISDNEthernet

FR

ATM

IP

MPLS

GbE

10/100 GbE

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Data Services: ISDN, FR, ATM, IP and MPLS, GbE

The telephone industry tried to provide multimedia services in the

late 80s using ISDN. This was an extension of the traditionaltelephone switched network to support other applications.

The Asynchronous Transfer Mode (ATM) or Broadband ISDN (B-ISDN) tried to increase the capacity and flexibility to support allexisting communication services. This is a packet switchedtechnology that offers quality of service using fixed size packets orcells.

The Internet Protocol (IP) was developed for computercommunications, but its characteristics and applications quicklydominated all other network protocols. The disadvantages arerelated to the higher delays and lower quality due to the routingprocess.

A Multi-Protocol Label Switched (MPLS) network tries to mix theflexibility of routed networks with the robustness of a switchedvirtual circuit. For an IP stream it creates a virtual circuit and thenassigns a label to the packets to expedite their processing.

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Type of Interfaces

Time Division Multiplex (TDM) interfaces

DS0 DS1 DS3 (PDH) STS-N (SONET) ADM, DXC, O-E-O OADM, O-E-O OXC

Packet Switch Capable interfaces

Routers, Switches, FR, ATM, LSR, etc.

Lambda Switch Capable interfaces OADM, OXC,

Fiber Switch Capable interfaces

Optical Patch Panel

Optical Protection Switch

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SONET/SDH Transmission Layer

IP Router

TDMDCS

ADM SONET ADMDCSDS0/TP

PL

DS-1/DS-3

DS-1/DS-3

DS-3OC-3

OC-12

Optical LayerOLT/OADM/OXC

OC-12c

OC-48c

OC-192c

IP Router

OC-3c

OC-12c

OC-48c

ATM

OPTICAL LAYER

SONET LAYER

IP

ATMPPP

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ATM AS SERVICE LAYER (Layer 2)

IP Router

TDMDCS

ADM ATMSWITCH

DS0/TP

PL

DS-1/DS-3

DS-1/DS-3

DS-3OC-3

OC-12

Optical LayerOLT/OADM/OXC

OC-12c

OC-48c

IP Router

OC-3c

OC-12c

ATM

OPTICAL LAYER

SONET LAYER

IP

ATM LAYER

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IP AS SERVICE LAYER (Layer 3)

IP Router

TDMDCS

ADM

SONET ADMDCS

DS0/TP

PL

DS-1/DS-3

DS-1/DS-3

DS-3OC-3

OC-12

Optical LayerOLT/OADM/OXC

OC-12c

OC-48c

OC-192c

IP Router

OC-12c

OC-48c

OC-192C

ATM

OPTICAL LAYER

SONET LAYER

IP

PPP