3. Evolution of network technologies

3.1. Evolution of transport technologies (backbone transport - switching/routing and transmission systems)

3.2. Evolution of access networks’ technologies to broadband (xDSL, CATV, Broadband Wireless Access)

3.3. Evolution of mobile networks (to 3G and beyond)

3.1. Evolution of transport technologies

A. Public Network Principles

Transport (Core/ Backbone) Network

Transmission

Network Terminations

Access Gateway

WirelessTechnologies

Access Network

Twisted Pair

Cable/Coax

Powerline

Optical Fiber

Switching/ Routing

These 3 techniques will be discussed next

Years1840 1900 1950 1975 1980 1990 2000

TelegraphManual switching

Electro-mechanics Analog Digital

Hand

telegraph

OperatorCr-B

55

QE

70

DE-1

PABX-1

PABX-2PABX-NG (IP)

Ethernet

Gbit Ethernet

Private

Pu

blic

ISDN

DE-NG (IP)

ATM

10 Gbit Ethernet

1884

Self-dial1935

(B-ISDN)

IP/X25/SMDS

FR

Cellular radio

GSM

UMTS/IMT-2000

DE-2

NMT

B. Evolution of switching technologies

G-MPLSMPLS

Switching technologies (Cntd)

CS(PSTN)

FR(FS, 70-s,

DN)

IP (PS-DG,

60-s, Internet)

Х.25 (PS-VC, 60-s,

DN)

MS(Tlg)

АТМ(CS, 80-s, B-ISDN)

Connection-oriented technologies

Connectionless-oriented technologies

ATMIP

OB

BACKBONE OPTIONS

Transport technologies in network backbones

MPLS

ATMIP

OB

BACKBONE OPTIONS

C. Transport technologies in network backbones - ATM

MPLS

ATM and the IETF model

ATM

• Layer 1/2 • Quality of Service (QoS)• Multimedia Transport

Constant Bit Rate (CBR) - Voice Variable Bit Rate (VBR) - WWW

Available Bit Rate (ABR) – E-mail Unspecified Bit Rate (UBR)

Application

Transport

Network

Data Link

Physical

Putting ATM to work

Voice• Delay• Delay Variation• Loss

Data• Delay• Delay Variation• Loss

Video• Delay• Delay Variation• Loss

Multimedia• Delay• Delay Variation• Loss

1 2 3 4 5

ATM QoS

• Constant Bit Rate for switched TDM traffic (AAL1): – Access Aggregation (TDM for GSM/GPRS, ATM for

UMTS)– Digital Cross-Connect

– Backbone Voice Transport - Basic

• Real-time Variable Bit Rate for bursty, jitter-sensitive traffic:

– Backbone Voice Transport – Advanced (AAL2)– Optional for Packetized Access Transport & Aggregation

(3G UTRAN, 2G CDMA)

• Non real-time Variable Bit Rate for bursty high priority data traffic:

– 2.5G data services

• Unspecified Bit Rate+ with Minimum B/W Guarantee for internal data:

– Operations, Admin & Maintenance (element management, stats collection, network surveillance, …)

– Billing data– Internal LAN traffic (email, web, file sharing, …) between

operator’s business offices

LINE RATE(LR)

CBR

nrt-VBR

ABR

UBRUBR+

rt-VBR

ATM’s role in the network’s segments

Premise• LAN/Desktop• Campus Backbone

Access• Low Speed (56/64)

• Medium Speed (E1)

• High Speed (>E1 to SDH)

• Integrated Access

Backbone• Voice• Data• Video• Multimedia

1 2 3 4 5

ATM and the “Competition”

Premise• LAN/Desktop - Ethernet, HS Ethernet, Gigabit Ethernet• Campus Backbone - HS Ethernet, Gigabit Ethernet

Access• Low Speed (56/64) - ISDN, ADSL • Medium Speed (E1) – xDSL, E1• High Speed (>E1 to SDH) - SDH• Integrated Access - E1, xDSL, SDH

Backbone• Voice Traditional Telephony, IP Backbones • Data Optical Backbones, IP Backbones • Video Optical Backbones, IP Backbones• Multimedia Optical Backbones, IP Backbones

ATM Summary

Multimedia

Not used much on Premise

Present use in Backbone

Predictable Performance/Guaranteed QoS

ATMIP

OB

BACKBONE OPTIONS

D. Transport technologies in network backbones - IP

MPLS

• Network Layer (Layer 3)

•

•End-to-End Addressing/Delivery•“Best Effort” Service

IP and the IETF Model

Physical

Data Link

Network

Transport

Application

IP

Putting IP to work

Voice• Delay• Delay Variation• Loss

Data• Delay• Delay Variation• Loss

Video• Delay• Delay Variation• Loss

Multimedia• Delay• Delay Variation• Loss

1 2 3 4 5

IP’s Role in the network’s segment

Premise• LAN/Desktop• Campus Backbone

Access• Low Speed (56/64)

• Medium Speed (E1)

• High Speed (>E1 to SDH)

• Integrated Access

Backbone• Voice• Data• Video• Multimedia

1 2 3 4 5

IP and the “Competition”

Premise•LAN/Desktop No Real Competition •Campus Backbone No Real Competition

Access•Low Speed (56/64) ISDN•Medium Speed (E1) xDSL, non-channelized E1•Integrated Access E1, multiple E1, Frame Relay, SDH

Backbone• Voice Traditional Telephony• Data Optical Backbones• Video Optical Backbones• Multimedia Optical Backbones, ATM Backbones

Why use IP?-Wide acceptance Internet popularity Global reach - IP Standards Mature standards Interoperability

IP Protocol characteristicsSimple protocolGood general purpose protocol

“Best Effort” Protocol

IP summary

Globally popular Originally developed for data Mature standards Interoperability “Best Effort” Protocol Voice over IP gaining popularity

We need a better Internet

Reliable as the phone

Next Generation Networks

Powerful as a computer

Mobile as a cell phone and

Working right away as a TV set

Main directions of improvement

1. Scalability

2. Security

3. Quality of service

4. Mobility

IPv6

ATMIP

OB

BACKBONE OPTIONS

E. Transport technologies in network backbones - MPLS

MPLS

• Routers that handle MPLS and IP are called Label Switch Routers (LSRs)• LSRs at the edge of MPLS networks are called Label Edge Routers (LERs) • Ingress LERs classify unlabelled IP packets and appends the appropriate

label.• Egress LERs remove the label and forwarding the unlabelled IP packet

towards its destination.• All packets that follow the same path (LSP- Label Switched Part) through

the MPLS network and receive the same treatment at each node are known as a Forwarding Equivalence Class (FEC).

AB

LER

LSR

LSRLER

LSP

MPLS Model

FEC

MPLS adds a connection-oriented paradigm into IP networks

E. Switching Technologies - Summary

• Driving forces (mid of 80th) - Common platform for different types of traffic

• ISDN is not suitable (N-ISDN - low bit rates, circuit switching)

• ATM will not become as the most important switching technology since 2000s

• Main competitors (Performance/Price) # Ethernet (LANs) # xDSL (Access) # IP/MPLS (Backbones)

ATMIP

OB

BACKBONE OPTIONS

F. Transmission technologies in network backbones - OB

MPLS

Stated data rates for the most important end-user and backbone transmission technologies -1

Technology Speed Physical Medium Application GSM mobile telephone service 9.6 to 14.4 kbps Wireless Mobile telephone for business and

personal use High-Speed Circuit-Switched Data service (HSCSD)

Up to 56 kbps Wireless Mobile telephone for business and personal use

Plain Old Telephone System (POTS) Up to 56 kbps Twisted pair Home and small business access

Dedicated 56Kbps on frame relay 56 kbps Various Business e-mail with fairly large

file attachments

DS0 64 kbps All The base signal on a channel in the set of Digital Signal levels

General Packet Radio System (GPRS) 56 to 114 kbps Wireless Mobile telephone for business and

personal use

ISDN

BRI: 64 kbps to 128 kbps PRI: 23 (T-1) or 30 (E1) assignable 64 kbps channels plus control channel; up to 1.544 Mbps (T-1) or 2.048 (E1)

BRI: Twisted pair PRI: T-1 or E1 line

BRI: Faster home and small business access PRI: Medium and large enterprise access

IDSL 128 kbps Twisted pair Faster home and small business access

AppleTalk 230.4 kbps Twisted pair

Local area network for Apple devices; several networks can be bridged; non-Apple devices can also be connected

Enhanced Data GSM Environment (EDGE) 384 kbps Wireless Mobile telephone for business and

personal use

Stated data rates for the most important end-user and backbone transmission technologies -2

Technology Speed Physical Medium Application

Satellite 400 kbps (DirectPC and others)

Wireless Faster home and small enterprise access

Frame relay 56 kbps to 1.544 Mbps

Twisted pair or coaxial cable

Large company backbone for LANs to ISP ISP to Internet infrastructure

DS1/T-1 1.544 Mbps Twisted pair, coaxial cable, or optical fiber

Large company to ISP ISP to Internet infrastructure

Universal Mobile Telecommunications Service (UMTS)

Up to 2 Mbps Wireless Mobile telephone for business and personal use (available in 2002 or later)

E-carrier (E-1) 2.048 Mbps Twisted pair, coaxial cable, or optical fiber

32-channel European equivalent of T-1

T-1C (DS1C) 3.152 Mbps Twisted pair, coaxial cable, or optical fiber

Large company to ISP ISP to Internet infrastructure

IBM Token Ring/802.5 4 Mbps (also 16 Mbps)

Twisted pair, coaxial cable, or optical fiber

Second most commonly-used local area network after Ethernet

DS2/T-2 6.312 Mbps Twisted pair, coaxial cable, or optical fiber

Large company to ISP ISP to Internet infrastructure

Digital Subscriber Line (DSL)

512 Kbps to 8 Mbps

Twisted pair (used as a digital, broadband medium)

Home, small business, and enterprise access using existing copper lines

Stated data rates for the most important end-user and backbone transmission technologies -3

Technology Speed Physical Medium Application

E-2 8.448 Mbps Twisted pair, coaxial cable, or optical fiber

Carries four multiplexed E-1 signals

Cable modem 512 kbps to 52 Mbps

Coaxial cable (usually uses Ethernet); in some systems, telephone used for upstream requests

Home, business, school access

Ethernet 10 Mbps 10BASE-T (twisted pair); 10BASE-2 or -5 (coaxial cable); 10BASE-F (optical fiber)

Most popular business local area network (LAN)

IBM Token Ring/802.5

16 Mbps (also 4 Mbps)

Twisted pair, coaxial cable, or optical fiber

Second most commonly-used local area network after Ethernet

E-3 34.368 Mbps

Twisted pair or optical fiber Carries 16 E-l signals

DS3/T-3 44.736 Mbps

Coaxial cable ISP to Internet infrastructure Smaller links within Internet infrastructure

OC-1 51.84 Mbps Optical fiber ISP to Internet infrastructure Smaller links within Internet infrastructure

High-Speed Serial Interface (HSSI)

Up to 53 Mbps

HSSI cable

Between router hardware and WAN lines Short-range (50 feet) interconnection between slower LAN devices and faster WAN lines

Fast Ethernet 100 Mbps 100BASE-T (twisted pair); 100BASE-F (optical fiber)

Workstations with 10 Mbps Ethernet cards can plug into a Fast Ethernet LAN

Stated data rates for the most important end-user and backbone transmission technologies -4

Technology Speed Physical Medium Application Fiber Distributed-Data Interface (FDDI)

100 Mbps Optical fiber Large, wide-range LAN usually in a large company or a larger ISP

T-3D (DS3D) 135 Mbps Optical fiber ISP to Internet infrastructure Smaller links within Internet infrastructure

E-4 139.264 Mbps

Optical fiber Carries 4 E3 channels Up to 1,920 simultaneous voice conversations

OC-3/SDH 155.52 Mbps

Optical fiber Large company backbone Internet backbone

E-5 565.148 Mbps

Optical fiber Carries 4 E4 channels Up to 7,680 simultaneous voice conversations

OC-12/STM-4 622.08 Mbps

Optical fiber Internet backbone

Gigabit Ethernet 1 Gbps Optical fiber (and "copper" up to 100 meters)

Workstations/networks with 10/100 Mbps Ethernet plug into Gigabit Ethernet switches

OC-24 1.244 Gbps

Optical fiber Internet backbone

OC-48/STM-16 2.488 Gbps

Optical fiber Internet backbone

OC-192/STM-64 10 Gbps Optical fiber Backbone

OC-256 13.271 Gbps

Optical fiber Backbone

Evolution of transmission technologies

Years1900 1970 1980 1990 2000

Frequency modulation, FDM

PDH

1935

Time multiplexing, TDM

Wavelength multiplexing

Tra

nsm

issi

on m

edia

Mod

ulat

ion

met

hods

Frequency modulation systemsSDH WDM

Copper cable

Copper cable

RadioCoax

CoaxFiber Optics

Satellite radio

Radio

all optical

Technological limitations of different transmission media

Optical fibers are the only alternative at high bandwidth and distancesOptical fibers are the only alternative at high bandwidth and distances

Mbit/s Limits of Transmission Media

0,1

1

10

100

1000

10000

0,1 1 10 100

Distance [km]

Tra

nsm

issio

n C

ap

acit

y [

Mb

it/s

]

Mbit/s Limits of Transmission Media

0,1

1

10

100

1000

10000

0,1 1 10 100

Distance [km]

Tra

nsm

issio

n C

ap

acit

y [

Mb

it/s

]Fiber

Coax

Cellular Wireless*

*Capacity in Mbit/s/sq_km, Bandwidth 500 MHz

250

Copper Twisted Pair

Optical systems move from backbone to access

Entry process of optical systems into access occurs very slowly... Prognosis 10-15 years, reason: exchange of copper cables and maturity of technologiesEntry process of optical systems into access occurs very slowly... Prognosis 10-15 years, reason: exchange of copper cables and maturity of technologies

yesterday

today

tomorrow

5 Years

10-15 Years

Access Metro Backbone

Copper Optical

ISDN POTSFiber optics and laser

Copper Optical

ADSL

Optical

additional: color filter and optical amplifier

additional: optical switch, color converter

Today optical transmission system consists mainly of electronics and passive optical

components

SDH networks:

WDM networks:

Signal Multiplexer Cross connector

Optical fiber

Amplifier

TDMMUX

TDM MUX,Cross-connect,control

Electricalsignal

Opto-electronics

Active optics

Passive optics

Electronics

• SDH and WDM process signals most of the time only electronically• Amplifiers are the only active optical elements in the network

Optical fiber

TDMMUX

WDM MUX,Cross-connect

Electrical signal

Active optics

Passive optics

Electronics

WDMMUX

Passive optics:- lenses- prisms- grating

Control

Passive optics:- lenses- grating- mirrors

Opticalsignal

Day after tomorrow:All-optical switching and multiplexing

• All-optical systems process signals only optically • Electronics disappear• Nortel (03/2002): large scale stand-alone optical switches

are likely for longer term market requirements

Optical fiberSwitchMatrix

Aktive Optik

Passive optics

WDMMUX

Passive optics:- lenses- prisms- grating

Control

Active optics:- Switch- color converter- amplifier

Opticalsignal

Signal Multiplexer SwitchAmplifier

Future photonic switches

• Optics are good for transport

• Electronics are good for switching

• Electronics as far as possible

Evolution instead of Revolution at least, 5 years for first all-optical systems in backbone and metro area

G. Concluding remarks - growth of network

capacity and “Death of distance” phenomenon • Growth of network capacity reduction of information

transmission costs• New generation of transmission systems – new ratio Cost of transmission/Bandwidth• PCM SDH/SONET DWDM • Bandwidth becoming a less dominating factor in cost of connection• Cost of one-bit-transmission has an obvious tendency to become very

close to zero in long distance communications systems• “Flattened” networks• “Death of distance” phenomenon (F. Cairncross, 1997)• Challenges for operators

Bandwidth using

• 32 terrestrial carriers connecting to the New York metropolitan area have a combined potential capacity of 818.2 Terabits per second. Of that, only 22.6 Terabits per second -- 2.8 percent -- of network bandwidth is actually in use

• Int'l IP       Using  City     Bandwidth,   Bandwidth,     

Gbit/s Gbit/s

London     550.3 9,5   Paris             399.4        9,3      

Frankfurt     320.2        10,3   Amsterdam  267.1 8,2  

Development of costs for IC sector

Source: Economist

0,01

0,1

1

10

100

1974 1979 1975 1985 1982 1994

years

$ p

er in

stru

ctio

n p

er s

eco

nd

Cray I

Digital VAX

Sun Microsystems 2

IBM PC

Pentium-chip PC

IBM Mainframe

0

50

100

150

200

250

300

350

1930 1940 1950 1960 1970 1980 1990 1996

years

US$

Cost of information processing $ per instruction per second Cost of a three-minute telephone call from New York to London, $

to be continued

to be continued