Uses existing telephony infrastructure v homeis

Uses existing telephony infrastructure
v
Homeis connected to central office
v
up to 56Kbps direct access to router (often less)
v
Can’t surf and phoneat sametime: not “always on”
Dial-up Modem

Introduction
telephone
network
DSL
modem
home
PC
home
phone
Internet
DSLAM
Existing phone line:
0-4KHz phone; 4-50KHz
upstream data; 50KHz-1MHz
downstream data
splitter
central
office
Digital Subscriber Line(DSL)
v
Also uses existing telephoneinfrastruture
v
up to 1 Mbps upstream (today typically < 256 kbps)
v
up to 8 Mbps downstream (today typically < 1 Mbps)
v
dedicated physical lineto telephonecentral office

Introduction 751-
75
Residential access: cable modems
q
Does not use telephoneinfrastructure
v
Instead uses cable TV infrastructure
q
HFC: hybrid fiber coax
v
asymmetric: up to 30Mbps downstream, 2 Mbps upstream
q
network of cable and fiber attaches homes to ISP router
v
homes share access to router
v
unlikeDSL, which has dedicated access

Introduction
O
N
T
O
L
T
central office
optical
splitter
O
N
T
O
N
T
optical
fiber
optical
fibers
Internet
Fiber to theHome
q
Optical links from central officeto thehome
q
Two competing optical technologies:
v
Passive Optical network (PON)
v
Active Optical Network (PAN)
Much higher Internet rates; fiber also carries television and phone

Introduction
100 Mbps
100 Mbps
100 Mbps
1 Gbps
server
Ethernet
switch
Institutional
router
To Institution’s
ISP
Ethernet Internet access
q
Typically used in companies, universities, etc
q
10 Mbs, 100Mbps, 1Gbps, 10Gbps Ethernet
q
Today, end systems typically connect into Ethernet switch

Introduction 781-
78
Wireless access networks
q
shared wireless access network connects
end system to router
v
via basestation aka “access point”
q
wireless LANs:
v
802.11b/g (WiFi): 11 or 54 Mbps
q
wider-area wireless access
v
provided by telco operator
v
~1Mbps over cellular system (EVDO,
HSDPA)
v
next up (?): WiMAX (10’s Mbps) over wide
area
base
station
mobile
hosts
router

Introduction 791-
79
Residential access: cable modems
Diagram:

Introduction 801-
80
CableNetwork Architecture: Overview
home
cable headend
cable distribution
network (simplified)
Typically 500 to 5,000 homes

Introduction 811-
81
CableNetwork Architecture: Overview
home
cable headend
cable distribution
network
server(s)

Introduction 821-
82
CableNetwork Architecture: Overview
home
cable headend
cable distribution
network (simplified)

Introduction 831-
83
CableNetwork Architecture: Overview
home
cable headend
cable distribution
network
Channels
V
I
D
E
O
V
I
D
E
O
V
I
D
E
O
V
I
D
E
O
V
I
D
E
O
V
I
D
E
O
D
A
T
A
D
A
T
A
C
O
N
T
R
O
L
1 2 3 4 5 6 7 8 9
FDM (moreshortly):