computer networks - Distributed Computing Group
COMPUTER
NETWORKS
Distributed
Computing
Group
Chapter 1
INTRODUCTION
Distributed
Computing
Group
Roger Wattenhofer
Winter 2003 / 2004
Computer Networks
Winter 2003 / 2004
Overview
What’s the Internet: “nuts and bolts” view
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What’s the Internet?
What’s a protocol?
Network edge vs. core
Access net, physical media
Performance: loss, delay
Protocol layers, service models
Backbones, NAPs, ISPs
History & Future
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Goal: get context, overview, “feeling” of networking,
postpone details.
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Millions of connected
computing devices: Hosts,
End-Systems
– PC’s, workstations, servers
– PDA’s, phones, toasters
running network applications
Communication links
– fiber, copper, radio
Routers
– forward packets (chunks)
of data through network
router
workstation
server
mobile
local ISP
regional ISP
company
network
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“Cool” Internet appliances
What’s the Internet: “nuts and bolts” view
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IP picture frame
[www.ceiva.com]
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World’s smallest web server
[www-ccs.cs.umass.edu/~shri/iPic.html]
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Web-enabled toaster and
weather forecaster
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•
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Human protocols
• “what’s the time?”
• “I have a question”
• introductions
… specific msgs sent
… specific actions taken
when msgs received, or
other events
cyberspace [Gibson]:
“a consensual hallucination experienced daily by billions of
operators, in every nation, ...."
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Computer Networks
workstation
server
mobile
local ISP
regional ISP
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What’s a protocol?
communication infrastructure
enables distributed
applications
– WWW, email, games, ecommerce, databases,
voting, file (MP3) sharing
communication services
provided
– connectionless
– connection-oriented
•
router
company
network
What’s the Internet: a service view
•
protocols: control sending,
receiving of messages
– TCP, IP, HTTP, FTP, PPP
Internet: “network of networks”
– loosely hierarchical
– public Internet versus
private Intranet
Internet standards
– RFC: Request for
comments
– IETF: Internet Engineering
Task Force
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Distributed Computing Group
Network protocols
• machines rather than
humans
• all communication activity in
Internet governed by
protocols
protocols define format, order of
msgs sent and received among
network entities, and actions
taken on msg transmission,
receipt
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What’s a protocol?
a human protocol
A closer look at network structure
and
a computer network protocol
•
Hi
TCP connection
req.
Hi
TCP connection
reply.
Got the
time?
•
GET http://distcomp.ethz.ch/index.html
2:00
Do you know other
human protocols?
•
<file>
network edge
– hosts and applications
network core
– routers
– network of networks
access networks, physical
media
– communication links
time
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Distributed Computing Group
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The network edge
Network edge: connection-oriented service
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end systems (hosts)
– run application programs
– e.g. WWW, email
– at “edge of network”
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client/server model
– client host requests,
receives service from
server
– e.g. WWW client (browser)
/server; email client/server
peer-to-peer model
– host interaction symmetric
– e.g. Gnutella, PeerMan
Goal: data transfer between end
systems
• handshaking: setup (prepare
for) data transfer ahead of time
– “Hello, hello back” human
protocol
– set up “state” in two
communicating hosts
• TCP
– Transmission Control
Protocol
– connection-oriented
service of the Internet
•
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TCP [RFC 793]
• reliable, in-order byte-stream
data transfer
– loss: acknowledgements
and retransmissions
• flow control
– sender won’t overwhelm
receiver
• congestion control
– senders “slow down
sending rate” when
network congested
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Network edge: connectionless service
Goal: data transfer between end
systems
– same as before!
•
UDP - User Datagram Protocol
[RFC 768]
– Internet’s connectionless
service
– unreliable data transfer
– no flow control
– no congestion control
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The network core
App’s using TCP
• HTTP (WWW)
• FTP (file transfer)
• Telnet (remote login)
• SMTP (email)
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App’s using UDP
• streaming media
• teleconferencing
• Internet telephony
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Circuit switching
– dedicated circuit per call
– telephone network
Packet switching
– data sent through network
in discrete “chunks”
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Frequency Division and Time Division Multiple Access
Circuit Switching
•
“graph” of interconnected
routers
the fundamental question: how
is data transferred through
net?
End-end resources
reserved for “call”
Divide link bandwidth
into “pieces”
– Frequency division
– Time division
dedicated resources
no sharing; “piece” is idle if
not used by user
circuit-like (guaranteed)
performance
call setup required
Example:
FDMA
4 users
frequency
time
TDMA
frequency
time
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Packet Switching
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Packet Switching
each end-end data stream
divided into packets
packets share network
resources
each packet uses full link
bandwidth
resources used as needed
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Bandwidth division into “pieces”
Dedicated allocation
Resource reservation
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resource contention
– aggregate resource
demand can exceed
amount available
congestion
– packets queue
– wait for link use
store-and-forward
– packets move one hop at a
time
– router receives whole
packet before sending the
first bit over the next link
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Circuit switching vs. Packet switching
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1 Mbit link
each user
– 100Kbps when “active”
– active 10% of time
10 Mb/s
Ethernet
A
statistical multiplexing
1.5 Mb/s
B
queue of packets
waiting for output
link
45 Mb/s
D
•
C
E
Real-world example for packet switching: Cafeteria (ETH Mensa)
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Packet Switching
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N users
1 Mbps link
•
circuit-switching
– 10 users
packet switching:
– with 50 users, Pr[more than 10 users active] < 1%
– with 100 users, Pr[more than 10 users active] ≈ 42%
•
Source breaks message into
smaller chunks: “packets”
Store-and-forward: switch
waits until one chunk has
completely arrived, then
forwards/routes
What if message was sent as
single unit?
Packet switching allows more users… Really?
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Circuit switching vs. Packet switching
Packet-switched networks: Routing
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Is packet switching a “slam dunk winner“?
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Great for bursty data
– resource sharing
– no call setup
But: Excessive congestion: packet delay and loss
– protocols needed for reliable data transfer
– header overhead
– congestion control
How to provide circuit-like behavior?
– bandwidth guarantees needed for audio/video apps
– still an unsolved problem
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Goal: move packets among routers from source to destination
We later study several path selection algorithms
datagram network
– destination address determines next hop
– routes may change during session
– analogy: driving, asking directions
virtual circuit network
– each packet carries tag (virtual circuit ID)
– tag determines next hop
– fixed path determined at call setup time, remains fixed
– routers maintain per-call state
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Computer Networks
Delay in packet-switched networks
Delay in packet-switched networks
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packets experience delay on
end-to-end path
four sources of delay at each
hop
transmission
A
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Nodal processing
– check bit errors
– determine output link
Queuing
– time waiting at output link
for transmission
– depends on congestion
level of router
B
queuing
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Note: s and R are
different quantities!
propagation
B
nodal
processing
1/22
Propagation delay:
– d = length of physical link
– s = propagation speed in
medium (~2x108 m/sec)
– propagation delay = d/s
transmission
A
propagation
•
Transmission delay:
– R=link bandwidth (bps)
– L=packet length (bits)
– time to send bits
into link = L/R
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nodal
processing
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queuing
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Queuing delay
“Real” Internet delays and routes: traceroute
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R=link bandwidth (bps)
L=packet length (bits)
a=average packet arrival rate
(packets per second)
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Arrival rate λ = La (bps)
Service rate µ = R (bps)
Traffic intensity ρ = λ / µ
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ρ small: average queuing delay small
ρ → 1: delays become large
ρ ≥ 1: more “work” arriving than can be serviced,
average delay grows infinitely!
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Computer Networks
Tracing route from photek.ethz.ch [129.132.13.122] to google.com [216.239.35.100]:
1 <10 ms <10 ms <10 ms rou-ifw-1-inf-vs.ethz.ch [129.132.13.65]
2 <10 ms <10 ms <10 ms rou-gw-switch-1-mega-transit-2.ethz.ch [129.132.99.213]
3 <10 ms <10 ms <10 ms swiez2.ethz.ch [192.33.92.11]
4 <10 ms <10 ms <10 ms swiIX1-G2-3.switch.ch [130.59.36.250]
5 <10 ms <10 ms <10 ms zch-b1-geth4-1.telia.net [213.248.79.189]
6 <10 ms 10 ms <10 ms ffm-b1-pos5-3.telia.net [213.248.77.133]
7 10 ms 20 ms 20 ms 213.248.68.90
8 10 ms 20 ms 20 ms de-cix.fra.above.net [80.81.192.226]
9 <10 ms 10 ms <10 ms so-0-1-0.cr1.fra1.de.mfnx.net [216.200.116.213]
10 10 ms 20 ms 10 ms pos9-0.cr1.cdg2.fr.mfnx.net [64.125.31.161]
11 40 ms 41 ms 50 ms so-5-0-0.cr1.lhr3.uk.mfnx.net [64.125.31.154]
12 100 ms 100 ms 100 ms so-7-0-0.cr1.dca2.us.mfnx.net [64.125.31.186]
13 170 ms 180 ms 170 ms so-3-0-0.mpr3.sjc2.us.mfnx.net [208.184.233.133]
14 170 ms 180 ms 180 ms so-0-0-0.mpr4.sjc2.us.mfnx.net [64.125.30.2]
15 170 ms 180 ms 180 ms so-1-0-0.cr2.sjc3.us.mfnx.net [208.184.233.50]
16 170 ms 180 ms 170 ms pos1-0.er2a.sjc3.us.mfnx.net [208.185.175.198]
17 160 ms 150 ms 160 ms sjni1-2-3.net.google.com [216.239.48.238]
18 170 ms 170 ms 160 ms sjbi1-1-1.net.google.com [216.239.47.162]
19 151 ms 150 ms 160 ms www.google.com [216.239.35.100]
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Networking Taxonomy
FDM
•
TDM
Packet Switching
Virtual Circuit
Datagram
We concentrate on right-hand path (predominant in Internet)
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Access networks and physical media
Network
Circuit Switching
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Q: How to connect end systems to
edge router?
• residential access nets
• institutional access networks
(school, company)
• mobile access networks
Keep in mind
• bandwidth (bits per second) of
access network?
• shared or dedicated?
1/27
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Residential access: cable modems
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Dialup via modem
– up to 56Kbps direct access to router (conceptually)
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•
ISDN
– integrated services digital network
– 128Kbps all-digital
connect to router
•
ADSL
– asymmetric digital subscriber line
– up to 1 Mbps home-to-router
– up to 8 Mbps router-to-home
– ADSL deployment: happening
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Other forms of cable modems
– Power line: e.g. Ascom Powerline
– TV cable modem: e.g. CableCom, Glattnet
– Satellite with feedback on phone line
– Wireless local loop
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Institutional access: local area networks
Wireless access networks
•
company/university local area network (LAN)
connects end system to edge router
•
Example: Ethernet
– shared or dedicated cable
connects end systems and
router
– 10 Mbps, 100Mbps,
Gigabit Ethernet
•
wireless LANs
– radio spectrum replaces wire
– 802.11b with 11 Mbps
– 802.11a with up to 54 Mbps
•
wider-area wireless access
– GSM: wireless access to
ISP router via cellular network
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deployment: institutions,
home LANs happening now
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shared wireless access network
connects end system to router
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[http://www.cabledatacomnews.com/cmic/diagram.html]
Residential access: point to point access
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router
base
station
mobile
hosts
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Home networks
Physical Media
Typical home network components
• ADSL or cable modem
• router/firewall
• Ethernet
• wireless access point
•
physical link
– transmitted data bit
propagates across link
•
guided media
– signals propagate in solid
media: copper, fiber
unguided media
– signals propagate freely,
e.g. radio
to/from
cable
headend
cable
modem
wireless
laptops
router/
firewall
Ethernet
(switched)
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Coaxial cable:
– wire (signal carrier) within a
wire (shield)
– variant baseband (“50Ω”)
• single channel on cable
– variant broadband (“75Ω”)
• multiple channels on
cable
– bidirectional
– 10Mbps Ethernet
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Twisted Pair TP (UTP, STP)
– two insulated copper wires
– Category 3
• traditional phone wires
• 10 Mbps Ethernet
– Category 5
• 100Mbps Ethernet
– Category 6
• 1Gbps Ethernet
wireless
access
point
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Physical Media: coax, fiber
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Physical media: Radio
•
Fiber optic cable:
– glass fiber carrying light
pulses
– high-speed operation:
100Mbps Ethernet
– high-speed point-to-point
transmission (>10 Gbps)
– low error rate
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•
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signal carried in
electromagnetic spectrum
no physical “wire”
bidirectional
propagation environment
effects:
– reflection
– obstruction by objects
– interference
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•
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Radio link types:
microwave
– e.g. up to 45 Mbps
Wireless LAN (802.11)
– 2Mbps, 11Mbps, 54Mbps
wide-area (e.g. cellular)
– GSM, 10’s Kbps
– UMTS, Mbps
satellite
– up to 50Mbps channel (or
multiple smaller channels)
– GEO: 270 msec end-end delay
– geosynchronous vs. LEO‘s
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Networks are complex!
•
many “pieces”
– hosts
– routers
– links of various media
– applications
– protocols
– hardware
– software
Organization of air travel
•
Questions:
•
Is there any hope of organizing
the structure of a network?
•
Or at least our discussion of
networks?
ticket (purchase)
ticket (complain)
baggage (check)
baggage (claim)
gates (load)
gates (unload)
runway takeoff
runway landing
airplane routing
airplane routing
airplane routing
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Organization of air travel: a different view
ticket (purchase)
ticket (complain)
baggage (check)
baggage (claim)
gates (load)
gates (unload)
runway takeoff
runway landing
airplane routing
airplane routing
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Layered air travel: services
Counter-to-counter delivery of person+bags
baggage-claim-to-baggage-claim delivery
people transfer: loading gate to arrival gate
runway-to-runway delivery of plane
airplane routing from source to destination
airplane routing
•
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Layers: each layer implements a service
– via its own internal-layer actions
– relying on services provided by layer below
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ticket (purchase)
ticket (complain)
baggage (check)
baggage (claim)
gates (load)
gates (unload)
runway takeoff
runway landing
airplane routing
airplane routing
Another example of layering
Arriving airport
Departing airport
Distributed implementation of layer functionality
airplane routing
[Tanenbaum]
intermediate air traffic sites
airplane routing
airplane routing
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Why layering?
Internet protocol stack (TCP/IP reference model)
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Dealing with complex systems
Explicit structure allows identification, relationship of complex
system’s pieces
– layered reference model for discussion
Modularization eases maintenance, updating of system
– change of implementation of layer’s service transparent
to rest of system
– e.g. change in gate procedure doesn’t affect rest of system
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application:
– ftp, SMTP, http
transport: host-host data transfer
– TCP, UDP
network: routing of datagrams
from source to destination
– IP, routing protocols
link: data transfer between
neighboring network elements
– PPP, Ethernet
physical: bits “on the wire”
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application
transport
network
link
physical
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ISO/OSI Reference Model
Layering: logical communication
•
Each layer
• distributed
• “entities”
implement
layer functions
at each node
• entities perform
actions, exchange
messages with
peers
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7 layers instead
– Application, Presentation, Session, Transport, Network, Data
Link, Physical
– Presentation: Syntax and semantics of information transmitted
– Session: Long-Term transport, such as checkpointing
3 central concepts
– Service: Tells what the layer does
– Interface: Tells the process above how to access the layer
– Protocol: How the service is performed; the layer‘s own
business.
application
transport
network
link
physical
network
link
physical
application
transport
network
link
physical
application
transport
network
link
physical
In this course, we use the Internet reference model
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Layering: logical communication
Example: transport
• take data from app
• add addressing,
reliability check
info to form
“datagram”
• send datagram
to peer
• wait for peer
to ack receipt
• Analogy:
post office
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data
application
transport
network
link
physical
ack
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Layering: physical communication
data
application
transport
transport
network
link
physical
application
transport
network
link
physical
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application
transport
network
link
physical
data
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network
link
physical
application
transport
network
link
physical
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data
application
transport
transport
network
link
physical
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application
transport
network
link
physical
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network
link
physical
application
transport
network
link
physical
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data
application
transport
network
link
physical
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Protocol layering and data
Internet structure: network of networks
•
•
•
Each layer takes data from above
– adds header information to create new data unit
– passes new data unit to layer below
M
Ht
M
Hn Ht
Hl Hn Ht
M
M
source
destination
application
transport
network
link
physical
application
transport
network
link
physical
M
message
Ht
M
segment
Hn Ht
Hl Hn Ht
M
datagram
M
frame
•
•
roughly hierarchical
national/international backbone providers (NBPs), a.k.a. “tier 1”
– e.g. UUNet, Sprint, Abovenet, AT&T, BBN/GTE, etc.
– interconnect (peer) with each other
local
ISP
privately, or at public Network
Access Point (NAP)
regional ISP
regional ISPs
NBP B
– connect into NBPs
local ISP, company
NAP
NAP
– connect into regional ISPs
NBP A
regional ISP
local
ISP
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Network of typical backbone provider
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Zur Geschichte der Kommunikation
•
•
Tontäfelchen (3000 v.u.Z)
Fackeltelegraphie
– bereits im 5. Jh. v.u.Z. (Griechenland)
•
Brieftauben
– Spätestens Mittelalter
•
Reiterboten
– Ab 1860
•
•
Trommeln, Spiegel, Flaggen, …
Optische Telegraphen
– Claude Chappe (Frankreich, 1791)
– Schweiz: ab 1850
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Protokoll von Polybius (2. Jhd. v.u.Z, Griechenland)
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•
•
•
Protokoll bei Optischen Telegraphen
Alphabet als 5 Gruppen zu 5
oder 4 Zeichen
2 Gruppen mit je 5 Fackeln
Verbindungsaufbau
1. Sendeabsicht: Heben von
2 Fackeln
2. Empfangsbereitsschaft:
Heben von 2 Fackeln
3. Senken der Fackeln
Datenübertragung für jedes Zeichen
1. Linke Fackelngruppe: Zeichengruppe anzeigen
2. Senken der Fackeln
3. Rechte Fackelngruppe: Zeichen anzeigen
4. Senken der Fackeln
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• Regeln für korrekten Nachrichtenaustausch
• Typischerweise synchrones Protokoll,
d.h. sendende Station muss Symbol
so lange zeigen, bis es von der
empfangenden Station bestätigt wird.
• Es gab ein Fehlersignal, mit
dem man wie bei “backspace”
das letzte Zeichen löschen konnte.
• Dieses Protokoll erinnert stark an
moderne Protokolle.
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Elektrische Telegraphen
Telefon
• 1774: 26 Drähte (unpraktisch)
• 1837: Elektrischer Zeigertelegraph
• Reiss (1863), Bell (1876), Edison (1877), Siemens (1878)
• “This ‘phone’ has way to many shortcomings to consider it
as a serious way of communicating. The unit is worthless
to us.” [Aktenvermerk Western Union, 1876]
• Ab 1880: Öffentliche Telefonnetze
– Cooke und Wheatstone
– 5 Magnetnadeln, jeweils 2 werden abgelenkt und zeigen auf 1 von 20(!) Zeichen
•
•
•
•
•
Man erreicht ca. 25 Zeichen pro Minute
1837: Samuel Morse
1851: Paris – London
1852: 6400km Kabel in England
1866: London – New York
– Zuerst maximal 30km Ausdehnung
– 20 Wörter kosten $100
• Eigenständige Industrie
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[New York 1895]
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Wireless Transmission
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•
•
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Weitere historische Meilensteine
1895: Guglielmo Marconi (1874 – 1937)
– first demonstration of wireless
telegraphy (digital!)
– long wave transmission, high
transmission power necessary (> 200kW)
– Nobel Prize in Physics 1909
1901: First transatlantic connection
1906 (Xmas): First radio broadcast
1907: Commercial transatlantic connections
– huge base stations (30 100m high antennas)
1920: Discovery of short waves by Marconi
1928: First TV broadcast
– Atlantic, color TV
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• 1964: Nachrichtensatelliten
• 1966: Glasfaser
• 1958 : Erste Analoge Handynetze: Deutsches A-Netz
– Vergleich PTT (Swisscom) NATEL: 1978 – 1995
• 1982 : Start der GSM Standardisierung
• 1997: Wireless LAN
• …
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Internet History 1961-72: Early packet-switching principles
1972-80: Internetworking, new and proprietary nets
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•
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1961: [Kleinrock] queuing
theory shows effectiveness of
packet-switching
1964: [Baran] packet-switching
in military nets
1967: ARPAnet conceived by
Advanced Research Projects
Agency
1969: first ARPAnet node
operational, first network with 4
nodes
•
1972
– ARPAnet demonstrated
publicly
– NCP (Network Control
Protocol) first host-host
protocol
– first e-mail program
– ARPAnet has 15 nodes
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•
•
•
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1970: ALOHAnet satellite
network in Hawaii
1973: Metcalfe’s PhD thesis
proposes Ethernet
1974: [Cerf and Kahn]
architecture for interconnecting
networks
Late 70’s:
– proprietary architectures:
DECnet, SNA, XNS
– switching fixed length
packets (ATM precursor)
1979: ARPAnet has 200 nodes
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Vinton G. Cerf and Robert E.
Kahn‘s (Ehrendoktoren der
ETH seit 1998) internetworking
principles:
– minimalism
– autonomy
– no internal changes
required to interconnect
networks
– best effort service model
– stateless routers
– decentralized control
¾ define today’s Internet
architecture
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1980-90: new protocols, a proliferation of networks
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•
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1983: deployment of TCP/IP
1982: SMTP e-mail protocol
defined
1983: DNS defined for nameto-IP-address translation
1985: FTP protocol defined
1988: TCP congestion control
Distributed Computing Group
•
•
1990’s: Commercialization, WWW
new national networks:
NSFnet, CSNET, BITnet,
Minitel
100,000 hosts connected to
confederation of networks
Computer Networks
Computer Networks
•
•
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Number of hosts in the Internet (lower bound)
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•
R. Wattenhofer
Early 1990’s: ARPAnet
decommissioned
1991: NSF lifts restrictions on
commercial use of NSFnet
(decommissioned, 1995)
early 1990s: WWW
– hypertext [Bush 1945,
Nelson 1960’s]
– HTML, http: Berners-Lee
– 1994: Mosaic, later
Netscape
– late 1990’s
commercialization of the
WWW
Distributed Computing Group
•
Late 1990’s
– est. 50 million computers
on Internet
– est. 100 million+ users
– backbone links running at 1
Gbps
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Internet Providers by “size” and “region”
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Internet Topology
[http://www.cybergeography.org/atlas/topology.html]
More Internet Topology
The image depicts
the Internet
topology. It shows
535,000-odd
Internet nodes and
over 600,000 links.
The nodes,
represented by the
yellow dots, are a
large sample of
computers from
across the whole
range of Internet
addresses.
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The SWITCH network
This graph
shows the
router level
connectivity
of the
Internet.
This graph is part
of a larger graph
and shows the portion of a
corporate Intranet that is
'leaking' with the Internet.
A topology
map of a
core
network of
a mediumsized ISP.
[http://www.cybergeography.org/atlas/topology.html]
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KPNQwest network as planned before collapse...
[www.switch.ch]
“The pan European
KPNQwest
network, when
complete, will
connect major cities
together by six
high-capacity
backbone rings.”
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Internet Users Worldwide
Global Online Population
Projection for 2004
709.1 million (eMarketer)
945 million (Computer Industry
Almanac)
Worldwide Internet Population 2002
445.9 million (eMarketer)
533 million (Computer Industry Almanac)
Nation
Population
Computer Networks
R. Wattenhofer
6.1 million
6.0 million
50
China
1.3 billion
33.7 million
N/A
3
Germany
83 million
26 million
15.1 million
123
Switzerland
7.3 million
3.4 million
1.8 million
44
Sudan
36 million
10,000
N/A
1
278 million
149 million
102.0 million
7,800
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Favorite Web Sites in Switzerland
[http://www.glreach.com/globstats/index.php3]
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ISPs
174.5 million
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Internet Languages
Active Users
(Nielsen/NetRating)
Brazil
United States
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Internet Users
(Source)
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•
According to Jupiter Media Metrix, 2.022 million visitors used the
Internet in Switzerland in February 2001 for an average of 9.5 days.
•
On an average day, 680‘000 visitors went online for 33 minutes and
viewed 27 unique pages.
•
Global sites from Microsoft, Yahoo, AOL and Lycos found under the
top rankings in all three language regions. National domains are
very strong. Bluewin.ch tops the list with an overall reach of 50
percent. Other national sites among the top 20 domains include
Search.ch (22 percent reach), SBB.ch (15.5 percent), Sunrise.ch
(11.8 percent), Swissonline.ch (10.2 percent) and UBS.com (9.9
percent).
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Internet Usage in Switzerland 2
[http://www.statistik.admin.ch]
Internet Usage in Switzerland
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The “Dot-Com Bubble”
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SPIEGEL: “Neustart im Netz”
Nortel
•
Not all Internet
companies are subject to
the bubble. Some major
ones are doing quite well
(Cisco, MS, IBM, etc.)
•
Many of my fellow
students work in the
networking or distributed
systems area (not that
this is a representative
subset)
Akamai
•
Distributed Computing Group
EBAY
AMAZON
Networking still important
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Course overview: Lectures and Exercises
Introduction
Overview
Applications: Email, WWW, etc.
More Applications and Sockets
Transport Layer: UDP and TCP
Advanced Transport Layer
Network Layer: Routing Basics
Advanced Network Layer
Link Layer: Aloha, etc.
Link Layer: Ethernet, Hubs, etc.
[XMas]
Physical Layer, Wireless
Peer-to-Peer Computing
Multimedia
Network Management
Conclusion
Distributed Computing Group
Literature
Intro
Course book
Andrew S. Tanenbaum
Computer Networks
Fourth Edition
Layer 5
Layer 4
Layer 3
German version
also available
Layer 2
There are alternatives, for example Kurose/Ross
Layer 1
Special Topics
Outro
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Organisation
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Other Courses, Master* in Distributed Systems
•
•
Kaum Unterschiede der Vorlesung im Vergleich zum letzten Jahr
Prüfung schriftlich, 90 Minuten, ab Herbst 2004
•
Alle weiteren Informationen auf dem Web:
http://www.distcomp.ethz.ch
Verteilte Systeme – A.M.W.
Übung jeweils Montag von 11 bis 12
Theoretische (Papier) und Praktische (Programmier) Übungen
Übungen in Gruppen von maximal 2 (T) bis 4 (P) Leuten abgeben
Übungen geben Punkte. Testatbedingung ...?
Erste Übung: Eintragen in Übungsgruppe (online!)
Vernetzte Systeme – Wattenhofer
•
•
•
•
•
Distributed Computing Group
Enterprise Application Integration* – Alonso
Parallel and Distr. Databases* – Alonso
Ubiquitous Computing* – Mattern
Distributed Algorithms* – Mattern
Mobile Computing* – Wattenhofer
Principles of Distributed Computing* – Wattenhofer
Alg. für Kommunikationsnetze – Erlebach
Web Algorithms – Wattenhofer & Widmayer
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