Transcript Overview to Telecommunication Systems

S-72.1130 Telecommunication
Systems
Overview
Practicalities
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Lecturers: Timo Korhonen (09 451 2351), Michael Hall (09 451 2322)
Tutorials: Mika Nupponen (09 451 5416), Naser Tarhuni (09 451 2362)
Exam: Monday, 17.12.2007, 9 - 12
No need to buy any books, however, following references can be useful:
 James F. Kurose, Keith W. Ross: Computer Networking, 2nd ed.
 A. Leon-Garcia, I. Widjaja: Communication Networks, 2nd ed.
 M. Duck, R. Read: Data Communications and Computer Networks,
2nd ed.
 W. Stallings: Data and Computer Communications, 7th ed.
 (Ericsson, Telia: Understanding Telecommunications, Part I & Part
II)
Grading: Closed book exam and voluntary tutorials:
 Round[ e (5 p) +t (5p) *0.15]
Lecture handouts:
http://www.comlab.hut.fi/studies/1130/lectures2007.htm
Homepage: http://www.comlab.hut.fi/studies/1130
Course feedback: http://palaute.ee.hut.fi/
HUT Comms. Lab, Timo O. Korhonen
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Lectures and tutorials
Lectures:
 21.11 Overview to Telecommunication Systems
 28.11 Public Switched Telephone Network
 29.11 Transport and Signaling in the PSTN
 5.12 Intelligent Network and Mobile Networks
 12.12 Wireless Local Area Networks
 13.12 Internet
Tutorials:
 First tutorial session will be on 29.11.2007, 12-14, S1
 A self-study tutorial to be returned 17.12.2007
 Check all tutorial info at:
http://www.comlab.hut.fi/studies/1130/Exercises/
HUT Comms. Lab, Timo O. Korhonen
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Course Topics
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Public Switched Telephone Network (PSTN)
Integrate Services Digital Network (ISDN) and SS7
Wireless Local Area Networks (WLANs)
The Internet, for instance…
 TCP/IP (Transmission Control Protocol/internet
protocol) Suite
 UDP (User Datagram Protocol in transport layer)
 SIP (Session Initiation Protocol in application
layer)
 QoS: MPLS (Multiprotocol Label Switching),
Differentiated Services
 Services
Telecommunications market
HUT Comms. Lab, Timo O. Korhonen
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Networking Subtopics
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User services as
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IN services: call last dialed, alternate billing services (as calling
card, collect call)
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Internet: web, email, ftp …
Terminals modems and PSTN/ISDN phones, user interfaces…
Routing and switching unicast - multicast, devices & protocols
(RSVP)
Transmission and links (fibre, coax-cable..)
Access and transport techniques (flow control, error control)
Signaling (SS7, X.25, Frame relay ...)
Network management (as OMAP of SS7...)
Interworking (gateways, bridges ...)
Network planning
Standards and
IN: Intelligent Network
recommendations: IETF: Internet Engineering Task Force
ITU-T, ITU-R,
IEEE: the Institute of Electrical and Electronics Engineers, Inc
IETF, IEEE,...
RSVP: Resource ReSerVation Protocol
ITU: International Telecommunications Union
SS7: Signaling System 7 (in ISDN)
OMAP: Operation and Maintenance Application Part
HUT Comms. Lab, Timo O. Korhonen
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Course Objectives
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Course discusses structure and properties of
telecommunications networks
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Network topologies
Protocols
Interfaces
Physical realizations
Role of abbreviations – understanding concepts
 Abbreviations refer (define) concepts
 Abbreviations describe standardized protocols & parts
of telecommunication systems
 More important to understand the meaning of concept
than to remember the words building up abbreviations
HUT Comms. Lab, Timo O. Korhonen
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History
1844 Steinheil’s
commercial telegraphy
1826 Ohm’s law
1800
1850
Volta:batteries; Fourier, Laplace, Cauchy: Mathematics
Morse, Kelvin:
Ampere, Faraday, Henry: Basic electronics
Early telegraphy
1864 Maxwell’s
1887 Strowger’s automated switch
electrodynamics
1850
1897 Marconi’s
wireless telegraphy
1900
Bell, Edison: Telephony
Heaviside, Pupin, Campbell: Theory of T.
1900
1918 Armstrong’s
heterodyne radio
1937 Alec Reeves’ PCM
1950 TDMA telephony
1950
Lee De Forrest: Triode-tube; 1969 ARPANET
Transcontinental telephone.
1972 Motorola’s
cellular system
1950 Communication’s electronic
1998 Digital TV
launched in USA
2000
Commercial data
services: DSP,
channel coding
HUT Comms. Lab, Timo O. Korhonen
trans-Pacific,
trans-Atlantic
optical cables
Internet,
Wide spread digital
signal processing
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Information Society
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“Information and Communication Anytime, Anywhere, and
in Any Form”
Key development fields
forming the business case:
Services
Legislation
/Regulation
/Standardization
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Global
Market
Technology
To understand how networks/terminals/services evolve consider
especially services because all network costs are paid by service
users:
Services shape telecommunications’ evolution and
effect greatly on which technology is chosen!
HUT Comms. Lab, Timo O. Korhonen
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Paradigm Shift
Old view
(circuit switched PSTN)
Speech
Low-rate
data modems (V.90)
Current view (packet switched Internet)
+ Other computers &
agent-programs (M2M)
SMS MMS
VoIP
http
HUT Comms. Lab, Timo O. Korhonen
DVB-H
ftp
smtp
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Components of Telecommunication Networks
Core Network
Node 1
Node 2
Access
Access
Node 3
Terminals
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Terminals
Internal structure can follow different
Core and access sub-network
topologies: mesh/star/bus/ring
(see also supplementary material)
Access part terminated by terminals
Network nodes and links are optimized for certain assumed
traffic (source statistics) and transmission channels (transfer
function and noise)
This model of telecommunication networks applies both to data
and voice networks (packet and circuit switching)
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Network Topology
Optical star-coupler
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Optical networks
Different topologies in
different networks
 BUS - Ethernet
 Ring - FDDI
 Mesh - Internet; Number
of connections required:
N ( N  1) N 2
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2
2
N: number of nodes
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Selection of topology
effects for instance
applicable MAC scheme
& network reliability
Example: FDDI: Token ring, Ethernet: CSMA/CD (an IEEE
802 technology)
HUT Comms. Lab, Timo O. Korhonen
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Tasks of a Telecommunication System
Input
Entity 3
Entity 3
Entity 2
Entity 2
Output
interface
Entity 1
Entity 1
Physical connection
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Initialization and release of link/across network
Synchronization RX & TX - carriers, start and end of frames/packets
Information exchange protocols determine protocols for
communication in entities: CSMA, CDMA, … TCP/IP
Error control - corrective measures
Addressing and routing
Message formatting, source coding
Therefore, networks realized by following a layered structure
(as Open System Interconnections (OSI) or TCP/IP stack )
NOTE: “Entities” refer to network elements as routers and bridges or
different OSI-layers
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Example: Routers, hubs and bridges
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Router is a device that extracts the destination of a packet
it receives, selects the best path to that destination, and
forwards data packets to the next device along this
path.They connect networks together; a LAN to a WAN for
example (link layer).
Hub (for instance Ethernet hub, USB hub)
 A device that allows many USB devices to be
connected to a single USB port
 Ethernet hub = multi-port repeater (concentrator)
 Works in physical level
Network bridge connects multiple network segments at
the data link layer
Ref: Wikipedia
HUT Comms. Lab, Timo O. Korhonen
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Development of
Data and Voice Networks
Earlier Scenarios
Voice/modems in PSTN
Leased lines
Frame Relay:
- applies virtual circuits
- example to connect LANs
- for high quality (links
have modest error
correction & flow control)
- rates: 2-50 Mb/s
Frame Flow Control:
(HDLC*)
- service for a pair of
communicating entities
- reassures non-overwhelming
communications (packets
could suffocate receiver )
*High-Level Data Link Control
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Nodes, links & layers with well-defined (standardized) interfaces
Network is optimized for certain, assumed traffic
Earlier Voice and data services in PSTN or data in dedicated
networks (X.25/Frame Relay)
Nowadays Internet carries both data and voice - QoS important!
HUT Comms. Lab, Timo O. Korhonen
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Current
Scenario
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ISDN, V.90,
Cable modem,
ADSL etc.
FireWire
Device
MPLS
Bluetooth
Device
WLAN
Router
Modified from W. Stallings: Data and
Computer Communications, 7th ed
(home site lecture slides)
HUT Comms. Lab, Timo O. Korhonen
*Synchronous Optical Networking
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Telecommunications Market
End-Users
Content and Service Providers
Service operators/
Telecommunications Networking Solutions
Physical Telecommunication Network
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Telecommunication network content and technology
producers, operators and consumers form an
interoperable hierarchy
HUT Comms. Lab, Timo O. Korhonen
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Telecomm Market Players
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End-users (individuals , companies, machine-to-machine
communications)
Information service providers (Telephone catalog services
designed by a company, giving telephone numbers when you
give a name or an address… Eniro)
Service brokers sell dedicated service packages (...MySAP)
Network operators (...Elisa, Telia, or Radiolinja)
Content providers (...Paramount Pictures)
HUT Comms. Lab, Timo O. Korhonen
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Evolving Telecommunication Services
PSTN-originated
services Call Holding/
International
Roaming
Call Waiting
Call Barring/
Call Forwarding
Data: 56 kb/s (V.90)
Pre-paid Services
Push-adds
Catalog Enquiry
Internet Access
Data: 9.6 Kb/s
… 380 kb/s
13 Kb/s Voice
Circuit/Packet
Switching: Mobility,
Data communication
*III Play=VoIP+DVB-H+Internet
HUT Comms. Lab, Timo O. Korhonen
Instant Messaging/Chat
Streaming: Video, Audio
WAP
Circuit Switching:
Voice services,
IN-services, limited data
Interactive Games
SMS
Voice Mail
Basic Voice
BW ~ 4 kHz
2.5G-3G
Services
2G Services
Data up to 2 Mb
Mobile Commerce
Push-to
Talk
10 Mb/s (HSDPA)
MMS
Rich Call: “See what I see!”
III Play*
Location Identification - Presence
All-IP: Location, mobility management, presence,
personalization, security
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Speech and Data Communications
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Speech
Data
Delays
Limited to ~200 ms
Depends on service
Errors
High tolerance
Very limited tolerance
Stream
Continuous: Circuit
switching
Bursty: Packet
switching
Teletraffic can be forced to fixed rate or bandwidth as
speech in PSTN or in ATM traffic
Waste of network resources follows if network resources
can not be reallocated on request (=statistical
multiplexing)
HUT Comms. Lab, Timo O. Korhonen
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Different Services Require
Different Transmission Rates
Voice
Maximum Rates of some
Transmission Technologies
Telephony
Broadcasting
Video conferencing
Video
TV/HDTV
Video
GSM 14.4 kb/s
HSCSD 56 kb/s
POTS 56 kb/s
GPRS 114 kb/s
EDGE 384 kb/s
Frame Relay 1.54 Mb/s
T-1 1.54 Mb/s
ADSL 8 Mb/s
Cable modems 52 Mb/s
Ethernet 10 M, 100 M, 1G
FDDI 100 Mb/s
OC-256 13.3 Gb/s
Data
Inter-LAN/PBX communications
Fax
Streaming with MPEG, MP3
10k
HUT Comms. Lab, Timo O. Korhonen
1M
100M
Bit rate (b/s)
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7 Application Layer
Type of communications:
E-mail, file transfer, client/server
6 Presentation Layer
TCP/IP Suite works
with 5 layers only
Encryption, data conversion:
ASCII to EBCDIC, BCD to binary ...
OSI Layers
5 Session Layer
Starts, stops session
maintains order
4 Transport Layer
Ensures delivery of entire file
or message
3 Network Layer
Routes data to different
LANs and WANs based on
network address
2 Data Link (MAC) Layer
Transmits packets form node to node
based on station address
1 Physical Layer
Electrical signals and
cabling
RTP: Real-time Transport Protocol (for internet telephony applications)
ICMP: Internet Control Message Protocol
(errors/IP package processing)
ARP: Address Resolution Protocol (data link address determination)
RARP: Reverse ARP (for instance DHCP host can ask its IP address)
BCD: Binary Coded Decimal
(four bits present each decimal digit)
EBCDIC - Extended Binary Coded Decimal Interchange Code (256 characters by 8 bits)
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Each OSI-layer has its Standardized Services
7. Application
NCP, FTP, Telnet, SMTP, SNMP, LAT, AFP, SMB...
6. Presentation
ACSE, ROSE, RTSE, ...
5. Session
NetBIOS, NetBEUI, DNS, ...
4. Transport
SPX, PEP, TCP, UDP, NSP...
3. Network
IPX, RIP, SAP, IDP, IP, ARP, RSVP, ICMP, X.25, RIP...
2. Data Link
IEEE 802.X, HDLC, ANSI X3T9.5, SMT,...
1. Physical
V.24, V.35, V.90, 10Base5, 10Base2, 10BaseT, FDDI,
SDH, G.703...
Understanding abbreviations: Wikipedia or Mpirical
(http://www.mpirical.com/companion/mpirical_companion.html)
HUT Comms. Lab, Timo O. Korhonen
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Protocols in Practice: Retrieving a Document from the Web
Addressing
Step:
1.
TCP/IP connection
2.
3.
4. –
6.
7. –
8.
HUT Comms. Lab, Timo O. Korhonen
Document
specifications
Document
response
Viewing the
document,
closing TCP/IP
The user clicks on a link to indicate which document
is to be retrieved. The browser must determine the
Internet address of the machine that contains the
document. To do so, the browser sends a query to
its local name server. DNS, UDP, HTTP, FTP, HTML
Once the address is known, the browser establishes
a connection to the server process in the specified
machine, usually a TCP connection. For the
connection to be successful, the specified machine
must be ready to accept TCP connections. TCP/IP
The browser runs a client version of HTTP, which
issues a request specifying both the name of the
document and the possible document formats it can
handle.
The machine that contains the requested document
runs a server version of HTTP. It reacts to the
HTTP request by sending an HTTP response which
contains the desired document in the appropriate
format. Document sent to the receiver.
The user may start to view the document. The TCP
connection is closed after a certain timeout period.
From Leon-Garzia, Widjaja: Communication Networks, 2th ed., Instructor’s Slide Set
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ITU-T Standards (www.itu.int)
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G - Transmission Systems and media, digital systems and
networks
H - Audiovisual and multimedia systems
I - ISDN
Q - Switching and signalling
V - Data communications over PSTN
X- Data networks and open system communications
Other important standardization organizations:
- IEEE (Institute of Electrical and Electronics Engineers)
- IETF (The Internet Engineering Task Force)
- ISO (International Organization for Standardization)
- ETSI (European Telecommunications Standards Institute)
Note that ITU-T standards nowadays available free-of-charge at ITU-T site
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Future Perspectives - PLMN
1995
2010
Single system support
Multi-system support
GSM, DECT
GPRS, EDGE, HSCSD, HSDPA
PSTN, ISDN
Voice, low rate data
Modest-rate
Push-to-talk,
VoIP
Internet
1992
HUT Comms. Lab, Timo O. Korhonen
2G: Data
compr.
2.5x
9.6 kb/s
1998
Terminals
UMTS/4G
WLANs
WiMAX
Radio
interfaces
Trunk
/Core
ATM, ISDN,
B-ISDN
TCP-IP/UDP
2G:
Fax/data/
SMS
9.6 kb/s
Software
radio
Portable,
Multimedia,
global
virtual
Virtual
reality
reality
Services
2.5G:
HSCSD
28.8 kb/s
2.5G:
GPRS
92 kb/s
2.5G:
EDGE
384 kb/s
3G:
UMTS
2 Mb/s
3G:
HSDPA
10 Mb/s
2000
2001
2003
2004
200525
Future Perspectives
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PLMNs and especially wireless LANs develop very
fast in home & office networks
Increasing data rates
QoS very important
Traffic gets more symmetrical (P2P)
PSTN:
 Used to transfer more and more data traffic
 Voice services of PSTN use IP (VoIP) and move
to Internet
Need of seamless communication of NGN means
that different networks must link efficiently ->
Inter(net)working between different kind of
networks important (example: Bluetooth-WLANUMTS)
HUT Comms. Lab, Timo O. Korhonen
PLMN: Public Land Mobile Network, IP:Internet Protocol
SLIP: Serial line IP
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Future Perspectives – Special Topics
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Sensor networking
 Autonomous, self-organizing
 Low power consumption
 Flexible topology
 High number of intelligent nodes
 Complex MAC-protocols
Usage of sensor networks
 Monitoring
 Body area networks (BANs)
Cross-layer design
Wire-replacement technologies
 Bluetooth
 Zigbee
 FireWire
HUT Comms. Lab, Timo O. Korhonen
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Web Resources
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Tutorials, links, abbreviations :
http://searchnetworking.techtarget.com/
Mpirical bank of abbreviations: http://www.mpirical.com/
companion/mpirical_companion.html
Wikipedia: http://en.wikipedia.org
Note: Many standards available online in the Library (as for
instance ITU-standards )
Have a look on course reference books homepages!
3:rd generation PLMN: www.w3.org, www.3gpp.org
Finish Spectral Regulation: www.ficora.fi
IEEE standards: www.ieee.org
ITU standards: www.iti.org
xDSL development: www.adsl.com
HUT Comms. Lab, Timo O. Korhonen
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Review Questions
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What does the concept of information society means?
Describe implications to technology/service
development.
What are the basic components and tasks of
generalized telecommunication network?
Give an example how telecommunication services
have evolved? What were the enabling changes in
technology?
What are the OSI layers? Give examples of their
tasks.
Summarize the expected development of mobile
telecommunication networks in terminals, radio
interface core network and in services
HUT Comms. Lab, Timo O. Korhonen
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S-72.1130 Telecommunication
Systems - Annex
What is …
(Some important concepts)
What is Ethernet?
Ethernet is the most widely-installed local area network (LAN)
technology. Specified in a standard, IEEE 802.3, Ethernet was
originally developed by Xerox and then developed further by
Xerox, DEC, and Intel. An Ethernet LAN typically uses coaxial
cable or special grades of twisted pair wires. Ethernet is also
used in wireless LANs. The most commonly installed Ethernet
systems are called 10BASE-T (100 m / CAT 3 cables) and
provide transmission speeds up to 10 Mbps. Devices are
connected to the cable and compete for access using a Carrier
Sense Multiple Access with Collision Detection (CSMA/CD)
protocol.
Fast Ethernet or 100BASE-T provides transmission speeds up
to 100 megabits per second and is typically used for LAN
backbone systems, supporting workstations with 10BASE-T
cards. Gigabit Ethernet provides an even higher level of
backbone support at 1000 megabits per second (1 gigabit or 1
billion bits per second). 10-Gigabit Ethernet provides up to 10
billion bits per second.
Source: Searchnetworking.com
HUT Comms. Lab, Timo O. Korhonen
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What is FDDI?
FDDI (Fiber Distributed Data Interface) is a set of ANSI and ISO
standards for data transmission on fiber optic lines in a local area
network (LAN) that can extend in range up to 200 km (124 miles). The
FDDI protocol is based on the token ring protocol. In addition to being
large geographically, an FDDI local area network can support
thousands of users. FDDI is frequently used on the backbone for a
wide area network (WAN).
An FDDI network contains two token rings, one for possible backup in
case the primary ring fails. The primary ring offers up to 100 Mbps
capacity. If the secondary ring is not needed for backup, it can also
carry data, extending capacity to 200 Mbps. The single ring can extend
the maximum distance; a dual ring can extend 100 km (62 miles).
FDDI is a product of American National Standards Committee X3-T9
and conforms to the Open Systems Interconnection (OSI) model of
functional layering. It can be used to interconnect LANs using other
protocols. FDDI-II is a version of FDDI that adds the capability to add
circuit-switched service to the network so that voice signals can also
be handled. Work is underway to connect FDDI networks to the
developing Synchronous Optical Network (SONET).
HUT Comms. Lab, Timo O. Korhonen
Source: Searchnetworking.com
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Multiprotocol Label Switching (MPLS)
Multiprotocol Label Switching is a standards-approved
technology (IETF: RFC 3031) for speeding up network traffic
flow and making it easier to manage. MPLS involves setting up
a specific path for a given sequence of packets, identified by
a label put in each packet, thus saving the time needed for a
router to look up the address to the next node to forward the
packet to. MPLS is called multi-protocol because it works with
the Internet Protocol (IP), Asynchronous Transport Mode
(ATM), and frame relay network protocols. With reference to
the standard model for a network (the Open Systems
Interconnection, or OSI model), MPLS allows most packets to be
forwarded at the layer 2(switching) level rather than at the
layer 3(routing) level. In addition to moving traffic faster
overall, MPLS makes it easy to manage a network for quality of
service (QoS). Note: ATM header overhead always at least 10
%, for MPLS it is order of magnitude smaller.
Source: Searchnetworking.com
HUT Comms. Lab, Timo O. Korhonen
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Streaming Technologies
Major streaming video and streaming media technologies include
RealSystem G2 from RealNetwork, Microsoft Windows Media
Technologies (including its NetShow Services and Theater
Server), and VDO. Microsoft's approach uses the standard
MPEG compression algorithm for video. The other approaches
use proprietary algorithms. (The program that does the
compression and decompression is sometimes called the codec.)
Microsoft's technology offers streaming audio at up to 96 Kbps
and streaming video at up to 8 Mbps (for the NetShow Theater
Server). However, for most Web users, the streaming video will
be limited to the data rates of the connection (for example, up
to 128 Kbps with an ISDN connection). Microsoft's streaming
media files follow Advanced Streaming Format (ASF).
Source: Searchnetworking.com
HUT Comms. Lab, Timo O. Korhonen
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Security and Secrecy*
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Services require security & secrecy, e. g. reliable, shielded
transfer (Example WEP of Wi-Fi). Especially important for
 NGN-services that are ‘near to users’
 Vulnerable services:
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medical/health as tele-surgery
rescue, police, defense
Networks can provide this in several network levels
(problem: overheads);
 fixed lines (PSTN, frame relay)
 flexible routing (SS7)
 scrambling or encryption (PLMNs)
 coding or ciphering (in all modern telecom links &
nets)
Often used concept: AAA: Authentication, Authorization,
Accounting
• Message goes to the right receiver
*
HUT Comms. Lab, Timo O. Korhonen
• Others can’t do eavesdropping
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What is AAA?
Short for authentication, authorization and accounting, a system in IP-based
networking to control what computer resources users have access to and to
keep track of the activity of users over a network.
Authentication is the process of identifying an individual,
usually based on a username and password. Authentication is
based on the idea that each individual user will have unique
information that sets him or her apart from other users.
Authorization is the process of granting or denying a user
access to network resources once the user has been
authenticated through the username and password. The
amount of information and the amount of services the user has
access to depend on the user's authorization level.
Accounting is the process of keeping track of a user's activity
while accessing the network resources, including the amount of
time spent in the network, the services accessed while there
and the amount of data transferred during the session.
Accounting data is used for trend analysis, capacity
planning, billing, auditing and cost allocation.
AAA services often require a server that is dedicated to providing the three
services. RADIUS is an example of an AAA service.
Source: www.webopedia.com
HUT Comms. Lab, Timo O. Korhonen
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What is Bluetooth?
Bluetooth is an industrial specification for wireless personal area networks (PANs).
Bluetooth provides a way to connect and exchange information between devices like personal
digital assistants (PDAs), mobile phones, laptops, PCs, printers and digital cameras via a
secure, low-cost, globally available ISM short range radio frequency.
Bluetooth lets these devices talk to each other when they come in range, even if they are not in
the same room, as long as they are within up to 100 metres (328 feet) of each other, dependent
on the power class of the product. Products are available in one of three power classes:
Class 3 (1 mW) is the rarest and allows transmission of 10 centimetres (3.9
inches), with a maximum of 1 metre (3.2 feet)
Class 2 (2.5 mW) is most common and allows a quoted transmission distance
of 10 metres (32 ft)
Class 1 (100 mW) has the longest range at up to 100 metres.
The specification was first developed by Ericsson, and was later formalized by the Bluetooth
Special Interest Group (SIG). SIG was established by Sony Ericsson, IBM, Intel, Toshiba and
Nokia, and later joined by many other companies as Associate or Adopter members. Bluetooth
is also IEEE 802.15.1 that specifies its radio interface by using frequency hopping.
HUT Comms. Lab, Timo O. Korhonen
http://en.wikipedia.org/wiki/Bluetooth
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Quality of Service (QoS)
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ATM, MPLS and UMTS support wide range of services that posses
different quality of service (QoS) requirements.
Transportation system differentiated into constant rate, real-time
and higher-latency services by Multi-Protocol Label Switching
(MPLS) or Differentiated Services (DiffServ)
User services can be divided to different groups, depending on QoS
requirements. Four traffic classes can been identified for ATM:
 Conversational class (very delay-sensitive traffic)
 Streaming class
 Interactive class
 Background class (the most delay insensitive)
Hence TCP (Connection-oriented transport-layer) is not a good
choice if errors can be tolerated
UDP (Connectionless transport-layer protocol) appropriate for
many streaming applications (error control in upper layers)
HUT Comms. Lab, Timo O. Korhonen
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Example from mpirical - database
http://www.mpirical.com/companion/mpirical_companion.html
HUT Comms. Lab, Timo O. Korhonen
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