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
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
• 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
• 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)
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