L1 by-mr
description
Transcript of L1 by-mr
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Syllabus Distribution (online)
• LIU Rules––
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Attendance policyExams
Academic Honesty
Withdrawal
Probations
In class behavior
• My rules– On time, honesty, hard working, reading
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Course outcomes
Identify the current approaches to design and implement broadband packet networks.
Outline the evolution of broadband networks generations.
Design a cost-effective network that meet the requirements of emerging technologies.
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• Explain the importance of broadbandmodern communication systems.
Learn the foundation and theory of theservice in modern networks.
networks for
• quality of
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Textbook and handouts
• Required text:– Connection-Oriented Networks: SONET/SDH,
ATM, MPLS, OPTICALG. Perros, Wiley 2005
QoS in Packet Networks,2005
NETWORKS Harry
– K. Park, Springer
• Handouts:– Will be delivered when needed
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Introduction
TOPICS––
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Overview of the Internet structure
Overview of the current networks implementation
Classification of communication systems
Examples of connections
Standards committees
1st generation of transport networks5
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Example of a Road Network
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Another road network
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Internet Structure
6Source Kurose & Ross
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Example of AT&T (Tier 1)
- Connects virtually every country and territory around the world.- More than 3,800 service nodes supporting MPLS-based services in 143 countries.- AT&T manages more than 200,000 MPLS customer ports.- A global carrier of IP and data traffic, carrying over 14,000 terabytes of traffic per average business day.- AT&T has one of the world's most powerful and advanced IP backbone networks, encompassing over 540,000
worldwide fiber-route miles - enough to circle the Earth at the equator more than 20 times.
Source http://www.telepresenceoptions.com/images/AT&T%20Network%20Map-thumb-450x227.jpg
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Another Global Network example
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D
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Networks of our days
Direct FiberCOAX
Tier 2Fiber
Tier 2IP/
MPLSD ernetSONET/ S
TDMPON Fiber Tier 2
PBB-TE
S3/E3
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Ethernet
BondedT1/E1
Ethernet
Ethernet
Ethernet
Ethernet
Ethernet
Bonded Copper
Eth
Direct Fiber
Ethernet
EthernetEthernetEthernet
WDM
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All-IP NetworksRegional office
CallManagerManager Router/GW
Router/GW
PSTN
HeadquarterIP WAN
DSL Access
InternetRouter/GW
VPN Access
Remote office
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Source www.cisco.com
Call
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Current Evolution in Cellular NetworksMigration to the all-IP cellular networks
In 4G, there will be no circuit swiching
All data (voice, video, web, ftp, etc.) will use IP IP convergence
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Source Alcatel-lucent 2008
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Classification of Communication Networks
EthernetPacket radio networkSatellite network
Telephone networkWavelength routing network
IP networkX.25ATMFrame relayMPLS
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Connectionless networksConnection-oriented networks
Packet–switched networksCircuit-switched networks
Broadcast communication networksSwitched communication networks
Communication networks
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Switched communication networks
– Circuit-switched networks:• The telephone network (PSTN)• Wavelength routing optical network.
Packet-switched networks:–••••
IP networkATMFrame RelayMPLS networks
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Broadcast communication networks
• Examples:
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packet radio networkssatellite networks
multi-access Ethernet.
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Packet-switched networks
• Connection-oriented networks––
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ATMFrame Relay
MPLS
• Connectionless networks
– IP
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Circuit-switched networks
In order for two users to communicate a circuit or a connection has to be first established by the network. Specifically, thefollowing three phases are involved:––
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circuit establishment,data transfer,
circuit disconnect.
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Connection-orientedpacket-switched
networks
• Circuitvoice,
switching is a good solution forasince it involves exchanging
relatively continuous flow of data.
• However, it is not a good solution for thetransmission of bursty data
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Connection-oriented packet-switchednetworks imitate circuit-switched network.
In order for two users to communicate avirtual circuit or a connection has to be firstestablished by the network.three phases are involved:
The following
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connection establishment,data transfer, and
connection disconnect.
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Connectionlesspacket-switched networks
In an IP network, a user can send packets to a destination without having to set up a connection first, i.e., without informing the network prior to transmitting them.
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• This simplifies thea special signaling
network, as there is no need forprotocol.
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Routing in IP
User A User B
IP network
The routing of a packet through the network is doneon a hop-per-hop basis based on the destination IPaddress carried in the IP packet’s header.
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Quality of Service (QoS) in IP
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Typically, an IP router does not offer QoS.It cannot distinguish packets belonging to different service classes based on their destination address.IP is almost ubiquitous. There has been a lot of interest in introducing QoS in the IP network, and MPLS seems to be the architecture of choice for introducing QoS.
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Examples of connections
Probably the oldest connection-orientedcircuit-switched network is the plain oldtelephone system (POTS).
Switch Switch
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Twisted pair SONETTwisted pair
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An ATM connectionATMATMATM
switch 1
switch 3switch 2
SETUPSETUP
SETUP
CONNECTCONNECT
CONNECT
A bi-directional connection is established using signaling.The connection is associated with an id number.
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SETUP
CONNECT
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• The switching of a cell through an ATM switch isdone based on its connection ID number.
A connection is associated with a specific class of service.
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• An ATM switch can distinguish cells belongingdifferent service classes, and serve them
to
accordingly so thatrequested QoS.
to provide them with the
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An MPLS connection
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The procedure is similar to ATM.
An MPLS-enabled IP router switches IP packets not on a hop-by-hop basis using the packet’s IP address. Rather, it forwards them using a label which identifies the connection that the packet has to follow.
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A wavelength routing opticalconnection
network
Router A OXC 1 OXC 2 OXC 3 Router B
1W1W 1W
A three-node wavelength routing network
Router A Router BOXC 1 OXC 2 OXC 3
A lightpath
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1 11 1
1W
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• An important feature of a wavelengthrouting optical network is that it is a circuit-switched network.
A connection is an optical path through the•optical network (called a lightpath) and it is
hopestablished using a wavelengthalong the connection’s path.
on each
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Summary
connectionless (IP network)
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Circuit switchedPacket switched with
Call establishment Required Not required
Dedicated physical path Yes No
Packets follow the same path Yes No
Packets arrive in sequence Yes No
Breakdown in core equipment is fatal Yes No
Availabilty in bandwidth Fixed, constant Dynamic, variable
When the congestion can occur On call establishment On every packet
Bandwidth is fully utilized No Yes
Transmission Store-and-Forward No Yes
Billing Per minute Per packet
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Standards Committees
ITU : International Telecommunication Union
ISO: International Organization for Standardization
ANSI: American National Standards Institute
IEEE: Institute of Electrical and ElectronicsEngineering
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IETF: InternetATM Forum
MPLS Forum
etc…
Engineering Task Force
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First Generation of TransportNetworks
TOPICS– History of the multiplexing
networksin circuit switched
– The PDH hierarchy
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PSTN History
• PSTN is the first telecommunicationnetwork (1875)– Based on circuit switched.
The subscriber is connected to the central office using a dedicated twisted pair (local loop).Multiplexing is done between two centraloffices to transport the calls of many users
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Multiplexing
• FDM (Frequency Division Multiplexing)used for analog signals.
TDM (Time division Multiplexing) used for digital signals PDH (Plesiochronous Digital Hierarchy)– How to digitize an analog signal (voice)?
WDM (Wavelength Division Multiplexing)used for optical signals
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First Step towards TDManalog signalDigitize the PCM (Pulse Code Modulation)
By sampling: take a sample every125 µsec.Then by quantification: represent the taken sample on 8 bits coding 8000 samples per seconde 8000 * 8 = 64 000 bits per second.
DS0 is the basic digital signal of 64 000 bits/sec34
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TDM
• Time division multiplexing allowssimultaneously by many users
The transmission is organized into
a link to be utilized
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frames.
Each frame contains a fixed number of time slots.
Each time slot is pre-assigned to a specific input link. The duration of a time slot is either a bit or a byte.
If the buffer of an input link has no data, then its associated time slot is transmitted empty.A time slot dedicated to an input link repeats continuouslyframe after frame, thus forming a channel or a trunk.
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Hierarchical Multiplexing in TDM
Two approaches:•– PDH (Plesiochronous Digital Hierarchy)
• Plesion means “nearly the same”, and chronos means“time” in Greek)..
• Frame Format (Ex: European standard, Tx: NorthAmerican standard).
SONET/SDH (will be explained next week)• SONET: Synchronous Optical NETwork (North
American).
• SDH: Synchronous Digital Hierarchy (European).37
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Synchronous vs Plesiochronous
• Synchronous Digital Multiplexers have tributaries with thesame clock frequency, and they are all synchronized to a master clock SONET/SDH
Plesiochronous Digital Multiplexers have tributaries that have the same nominal frequency (that means there can be small difference from one to another), but they are not synchronized to each other PDH
For synchronous case, the pulses in each tributary all rise and fall during the same time intervalFor the PDH, the rise and fall time of the pulses in each
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•tributaries do not coincide with each other
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PDH: T carrier / E carrier
• The DS signal is carried over a carrierknown as the T carrier.– T1 carries the DS1 signal,
– T2 carries the DS2 signal etc…
system
• The ITU-T signal is carried oversystem known as the E carrier.
a carrier
• The DS and ITU-T hierarchy is known asplesiochronous digital hierarchy (PDH).
the
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The DS1 signal in T1
slot 24
• 24 (8-bit time slots)/frame– Each time slot carries 8 bits/ 125 µsec,
channel carries a 64 Kbps voice.or the
– Every 6th successive time slot (i.e, 6th, 12th,18th, 24th, etc), the 8th bit is robbed and it is used for signaling.
• F bit: Used for synchronization. It transmitsthe pattern: 101010110…
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FTime slot 1
Time slot 2
Time slot 3 . . .
Time
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The DS1 signal in E1
• E1– 30 voice time slots plus
and control2 time slots for synchronization
– Total transmission rate: 32x8 = 256 bits per 125 sec,or 2.048 Mbps
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T1 frame for voice
24 time intervals, each one is composed of 8 bits (192 bits)
1 « Framing bit »8 bits per « timeslot » per DS1 frame
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T1 frame for data (fractional T1)It is possible to have a partial or an entire DS1•
• A partial DS1 allows to have multiple throughputsof 64kbps
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DS1, DS3 over SONET