Transcript Layout

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The Göttingen Wireless LAN
Gerhard Schneider
Gesellschaft für wissenschaftliche Datenverarbeitung Göttingen
and Universität Göttingen
[email protected]
http://www.gwdg.de/~gschnei2
Motivation -1• Fact: The internet is at the desk and files/information are
available digitally
• The laptop is the (future) working environment (portable!)
– And other portable devices
• Outside your office everybody tries to keep you away from the Internet
– Where do you find the nearest Internet access point? And may you use it?
• How many access points do you find in this resort??
– are you allowed to access the Internet in your own company/university
everywhere??
• In the meeting room to download your digital information
• In other departments to read your mail during session breaks
• And even if you could (technically), King SysAdmin happens to be far away
– “This is not for everybody”, „you are a security risk“, etc
• So one is dreaming of the Internet and its multi media options but even two
inches away from a connected computer you are in Network-Never-NeverLand
– and in frustration you use your mobile phone
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Motivation -2• In Göttingen some 4000 dorms are networked, mostly fibre or 100 Mbit/s
– Top position in Germany (according to the statistics of the Deutsches
Studentenwerk
– Makes dormitories very attractive for students
• Internet access from the bed, but from nowhere else?
– What about private places?
• In a library there is almost no possibility to use the own laptop for online
research
– Use of existing PC for research is no problem
• (Göttingen offers several hundred “public” terminals, so there is an option)
• transfer of the results to a server
– At home download the data onto the private laptop
• Which you had with you in the first place
• Even when the weather is fine, surfing the net can only be done in your
(dark) room.
– Bad social image
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Motivation -3• Main problem: Internet access is seen as a local phenomenon, not as a
global need.
• Personal vision: always online at little cost and with high performance
– Also because of my PDA (personal digital assistant)
• Current twists to synchronise data are far from optimal
• Question: what happens, if you are always online and the tedious search for
the net has become history?
– Compares with the continous search for food in contrast to always finding a
well laid table
– Remember the Woody Allen film, where a character is constantly calling the
secretary to leave his current phone number?
• Now solved by mobile phones...
• First experiments in 1995, using proprietary Breezecom technology
• Now we have a standard 802.11b – new motivation
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20.4.2000
first trial „Göttinger FunkLAN“
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Experiences from the trial
• A wireless LAN only makes sense, if it is available (almost) everywhere.
– Not just in one building, but really everywhere
– Everywhere means: global management and global operation
• Equal access: all net citizens are equal
• In Göttingen, science happens to be everywhere
– The scattered buildings scattered over town are a nightmare for networking
people, but a dream for the wireless operator
• Many points for transmitters at little extra cost
– In addition all schools are online via fibre optic or ADSL
• So instead of going for a 100% coverage of a few university complex rather
go for a (more or less) general coverage of the city
– Trick: wireless technology goes in all directions, so a transmitter happens to
cover surrounding areas.
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Göttingen’s Data Network
for Science and Research
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The local high speed networt GöNet, started in 1991, connects the
following institutions at gigabit speed:
•
University of Göttingen
–
•
•
•
Max Planck Institute for Biophysical
Chemistry
•
URL: http://www.mpibpc.gwdg.de
Max Planck Institute for fluid
Dynamics
–
URL: http://www.iwf.de
URL: http://www.geschichte.mpg.de
Max Planck Institute for
Experimental Medicine
–
URL: http://www.mpiem.gwdg.de
GWDG
–
URL: http://www.gwdg.de
•
City of Göttingen
•
Primatenzentrum
URL: http://www.gwdg.de/mpisf
Institute for the scientific Film
Max Planck Institute for
Historical Science
–
(in Katlenburg-Lindau, some 30km outside of
Göttingen – dark fibre)
– URL: http://www.mpae.gwdg.de
–
•
URL: http://www.uni-goettingen.de
Max Planck Institute for Aeronomy
–
•
•
(since 3/99 – with the local schools)
– URL: http://www.goettingen.de
– URL: http://www.goe.ni.schule.de
–
URL: http://www.dpz.de
LANs in
Göttingen
• University founded in 1734/37
• Two Campuses and many little
buildings scattered all over town.
Backbone
1 Gbit/s
– Observatory of C. F. Gauss
– Oldest Institute for Geophysics in
the world.
– World‘s first data highway
The first data highway:
Gauss-Weber 1833: 1 bit/Sek
Today‘s
fibre optic
backbone:
Wireless
LAN:
1.000.000.000
currently
11.000.000times
timesfaster
faster
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Remarks about the
technology
• WAVELAN 802.11b
– Unrestricted operation in the 2,4 GHz range
– “CB-network” with no guarantee for exclusive access/use
– Range restricted by law:
• short range: 100 mW power
• long range: 30mW power
• 1/20 bis 1/60 of a mobile phone (900 MHz bzw. 1.800 GHz)
– Range up to 300m with normal antennas
• Antennas are reasonably invisible (compared with GSM)
• Range up to 4km already observed (using special and legal antennas)
• Inside of buildings the range is much less
– LAN-connection is still required
– Up to 11 Mbit/s in one cell
• Several cells may cover an area, up to 128 users per cell.
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Technology (1)
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A
n
t
e
n
n
a
Pccard for the notebook
Access Point
(connection to the LAN)
Technology (2)
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6 dBi Patch
DIR-060-01
5.2 dBi Omni (outdoor)
OMN-052-02
13.5 dBi Yagi
DIR-135-01
12 dBi Omni
OMN-120-01
21 dBi Solid Dish
DIR-210-01
Project money from
“nds. MWK” and BMBF
• This was what we needed to boost our wireless network: € 250.000
– 50% “nds. MWK” = niedersächsisches Ministerium für Wissenschaft und
Kunst = Ministry for Research and Arts, Lower Saxony
Minister Thomas Oppermann
– 50% BMBF: = Bundesministerium für Bildung und Forschung = Federal
Ministry for Education and Research
Ministerin Edelgard Bulmahn
• some 150 Access-Points can be financed
– Partly with dual card, i.e. with one access point we can provide service inside
and outside of the buildings by suitably placing the antennas
• some 250 WaveLAN cards for loan to students
• A few laptops for loan, including an iPAQ
– Boosts the acceptance of lpatops w.r.t. real computers
– Laptops are finally affordable, about €1500 at the food store ALDI
• So far good acceptance from everybody
– Colleagues showing off the new infrastructure to visitors!
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The right
antennas…
• By use of special antennas larger
distances can be covered, provided
there is direct (unhampered)
visibility
– 11 Mbit/s up to 4 km
– Blauer Turm as first long range
access point, city hall will follow
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Security concepts
• Access is only granted to cards having a valid
identification
– Check the MAC-adresse against radius database
• Communication between card and access point is
encrypted
– Generic standard WEP
• This appears far from being secure, thus:
– No connection between the Wireless LAN backbone and
the “normal” network GöNET
– Only after logging in at a gateway we grant access to the
Internet (VPN-Technology)
• Typically used for “external” dial-in
– Connection between user and gateway is encrypted
using VPN software and its scientifically approved
encryption methods
CZ, 8.2.2001
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Access to the wireless
network
• Is this a bottleneck? No!
– We can install several gateways
– The backbone offers enough capacity to cope with the incoming
wireless traffic
– We can/could talk about separate user groups/users administration
• Faculty gateways 
(but better than a separated net)
• Advantage: Integration of other user groups into the
infrastructure
– Get more money to expand the network
– Example: companies could also use a relatively wide spread network
• Measurement Valley
• local Internet provider
• City radio – use the GöNET for Internet radio 
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Wireless LAN – modes of
operation
• Central axiom from our point of view:
a wireless network is more than a local network
– Not an extension of the old idea of a wire based telephone system, but
roaming as we know it from the mobile world
– At this point many institutions commit their central design error!
• Not a centralistic concept, but a concept which scales even for
several operators
– GWDG-user (science&research), student user, faculty
• Target: one wireless network for all scientists and students in
Göttingen
– „Internet always on“ – well, “almost everywhere
– Access is possible everywhere, using the same rules
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Wireless LAN – modes of
operation
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Gateway
Shared 11 Mbit/s
Router
GöNET
G-WiN
New partners
• The local bank (Sparkasse Göttingen)
– Transmitters may be placed inside and outside three “crucial” branch offices
• Connection to GöNET via dark fibres from the bank network
– Easy online banking
• Siemens-Fujitsu
– 100 high end laptop computers for students sponsored
• Model B2175 and model E6560 at €1300
• It pays to be a student 
• City of Göttingen
– Will grant access to the town hall “skyscraper”
– Will donate PCMCIA-WaveLAN-cards to students who take up residence in
the city of Göttingen
• (rather than stay in their home town – tax reasons)
• Suddenly our project is affecting the competition of cities 
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Future working conditions
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Voice
over IP?
Finally a clean desk
Internet and more
• After all, digitised voice is data!
– Not really understood in society, parliament, legislation
• GWDG is experimenting with Voice over IP
– Solution by Siemens: Software running on a PC
– VoIP-Gateway to our PABX already installed
– Real telephone calls from your PC….
• Including real blue screens
• Build your own mobile phone with this?? No, after all:
– www.spectralink.com (VoIP-mobile based on 802.11b)
• New questions
– why DECT????
• If we can scrap the DECT project of the university PABX, we have more money for
WaveLAN
– why UMTS????
• Compared to the € 50 billion licence fees in Germany, WaveLAN is really cheap
• http//www.tagesschau.de/archiv/2001/03/21/sendungen/tt-2230/videos/cebit.ram
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Data and “voice” over one
wireless network
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Voice is no longer an expensive special case
WAN
PSTN
Connection to
the old world
Summary:
wireless vs traditional LAN
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• Wireless is easy to install
– Especially when it comes to respect conservation laws
• Wireless is „shared“ media
– 802.11b gives at most 11 Mbit/s for all participants in one cell
– „good old“ Ethernet in a new box
• With all its disadvantages
• In Göttingen the wireless LAN is an additional offer for the „roaming user“
– Cabling infrastructure is expanded constantly
– Connect remaining sites to GöNET fast
– Instant cover of large rooms
• library, Café,
– No replacement for cabling infrastructure
w.r.t. multimedia
Library in the Paulinerkirche
Future conferences?
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Only portable – no – wearable!
900g on belt or arm, 233 MHz, 128 MB RAM, 4,3 GB HDD, 2x
PCMCIA, Audio I/O, USB, ext. scanner, ext. keyboard, ext. mini camera