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8/2/2019 Introduction to Network Structure and Protocol
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Fundamentals of Networking:
Introduction to Network Structureand Protocol
Dr. Hania Farag
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Overview
1
Monday, September 12, 2011
Basic concepts in communications
Understanding Networking.
Understanding Transmission Medium (Network
Cables) Understanding Network Hardware
Understanding Network Protocols
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Overview
2
Monday, September 12, 2011
Basic concepts in communications Understanding Networking.
Understanding Transmission Medium (Network
Cables)
Understanding Network Hardware
Understanding Network Protocols
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Basic Concepts in Communication
3
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Communicationsactivity associated with distributingor exchanging information
Telecommunicationstechnology of communications at
a distance that permits information to be created any
where and used everywhere with little delay Today it, involves
Data: digital and analog
Voice: spoken word
Video: telelcommunication imaging
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Essentials for Communications
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Message
Transmitter / Receiver Medium
Message must be understood
Some level of security
Source Transmitter Transmission Receiver Destination
Source System Destination System
Workstation/PCWorkstation/PC
Medium
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Overview
5
Monday, September 12, 2011
Basic concepts in communications Understanding Networking.
Understanding Transmission Medium (Network
Cables)
Understanding Network Hardware
WAN and LAN
Understanding Network Protocols
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What do you see here for a typical network?
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Key Network Terminology Explained (1)
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Networks needs to interconnect at a distance by aform of point to point or point to multiple point
connected media
Networks that are interconnected have proven to be
low cost, reliable, and efficient means of
communicating at a distance
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Key Network Terminology Explained (2)
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Node: anything connected to the network, usually a
computer, but it could be a printer or a scanner
Segment: any portion of a network that is separated by a
switch, bridge or a router from another part of a network.
Backbone: the main cabling of a network that all of thesegment connect to. Usually, the backbone is capable of
carrying more information than the individual segments.
Topology: The way each node is physically connected to
the network
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Key Network Terminology Explained (3)
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Simplex: information flows in only one direction
Half-duplex: information flows in two directions, but
only in one direction at a time.
Full-duplex: information flows in two directions atthe same time
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Basic Signal Terminologies
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Bit: binary digit, either 0 or 1
Baud : one electronic state change per second
Bit rate :a method for measuring data transmission
speedbits per second
Mbps : millions of bits per second (data speed;measure of bandwidth = total information flow over
a given time) on a telecommunication medium
8 bits = 1 byte
Teraflops : trillion operations per second
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TYPES OF NETWORKS
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LANLOCAL AREA NETWORK IS A SMALL
GEOGRAPHICAL AREA SUCH AS OUR SCHOOLBOARD.
MANMETROPOLITAN AREA NETWORK IS A
NETWORK OVER A LARGER GEOGRAPHICAL AREA
SUCH AS THE PROVINCIAL GOVERNMENT.
WANWIDE AREA NETWORK IS A NETWORK USED
OVER AN EXTREMELY LARGE GEOGRAPHICAL AREA
SUCH AS THE FEDERAL GOVERNMENT.
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Topologies
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Physical layout of network devices
Four types: mesh, bus, ring, and
star
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Mesh Topology
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Mesh Topology
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It is also called apoint-to-pointtopology. Each device is connected directly to all other
network devices.
It provides fault tolerance.
It is only found in wide area networks.
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Bus Topology
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Bus Topology
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It is a multipointtopology. Each device shares the connection.
The bus has one starting and one ending point.
Packets stop at each device on the network. Only one device at a time can send.
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Ring Topology
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Ring Topology
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It is a circle with no ends. Packets are sent from one device to
the next.
It does not slow down as more
devices are added.
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Star Topology
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Star Topology
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All devices are connected to a central device(hub).
The hub receives and forwards packets.
It is the easiest topology to troubleshoot and
manage.
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Hybrid Topologies
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They are variations of two or more topologies.
Star busused to connect multiple hubs in astar topology with a bus.
Star ringwired like star, but functions like a
ring.
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Star Bus Topology
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Design Considerations
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The best topology involves matchingwith the environment it is to be usedin.
The physical arrangement ofcomputers do not dictate the necessarytopology.
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Overview
2
Monday, September 12, 2011
Basic concepts in communications
Understanding Networking.
Understanding Transmission Medium (Network
Cables)
Understanding Network Hardware
WAN and LAN
Understanding Network Protocols
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Basic transmission medium concepts
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Medium is the physical path between transmitter and
receiver in a data transmission system
Guided Medium: waves are guided along a solid
medium path (twisted pair, coaxial cable, and optical
fiber). Unguided medium: waves are propagated through
the atmosphere and inner/outerspace (satellite, laser,
and wireless transmissions).
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Medium examples by type
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Conductive: twisted pairs and coaxial cables
Electromagnetic: microwave
Light: lasers and optical fibers (need clear line of
sight)
Wirelessinner/outerspace; satellite(omnidirectional security issues)
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Coaxial cable (1)
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Widely installed for use in business and corporation
ethernet and other types of LANs. Consists of inter copper insulator covered by
cladding material, and then covered by an outer
jacket
i l bl
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Coaxial cable (2)
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Applications:
TV distribution (cable tv); long distance telephonetransmission; short run computer system links
Local area networks
Transmission characteristics: Can transmit analog and digital signals
Usable spectrum for analog signaling is about 400
Mhz
T i d P i C bl
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Twisted Pair Cable
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T i d P i C bl
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Twisted Pair Cables
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Physical description:
Each wire with copper conductor
Separately insulated wires twisted together to reduce cross talk
If enclosed in a sheath then is shielded twisted pair (STP) otherwise often
for home usage unshielded twisted pair (UTP). Must be shield from
voltage lines
Application: Common in building for digital signaling used at speed of 10s Mb/s
(CAT3) and 100Mb/s (CAT5) over 100s meters.
Common for telephone interconnection at home and office buildings
Less expensive medium; limited in distance, bandwidth, and data rate.
C i f T i d P i C bli S
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Categories of Twisted Pairs Cabling System
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Category Maximum datarate
Usual application
CAT 1 Less than 1 Mbps analog voice (plain old telephoneservice) Integrated Services DigitalNetwork Basic Rate Interface in ISDNDoorbell wiring
CAT 2 4 Mbps Mainly used in the IBM Cabling Systemfor token ring networks
CAT 3 16 Mbps Voice and data on 10BASE-T Ethernet(certify 16Mhz signal)
CAT 4 20 Mbps Used in 16Mbps Token Ring
Otherwise not used much
CAT 5 100 Mbps 100 Mbps TPDDI
155 Mbps asynchronous transfermode (certify 100 Mhz signal)
O ti l fib
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Optical fiber
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O ti l Fib
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Optical Fibers
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Physical Description:
Glass or plastic core of optical fiber = 2to125 m
Laser or light emitting diode provides transmission lightsource
Applications:
Long distance telecommunication Greater capacity; 2 Gb/s over 10s of Km
Smaller size and lighter weight
Lower attenuation (reduction in strength of signal)
Electromagnetic isolationnot effected by externalelectromagnetic environment.
Wi l T i i
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Wireless Transmission
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Frequency range (line of sight): 26 GHz to 40 GHz: for microwave with highly directional
beam as possible
30 MHz to 1 GHz: for omnidirectional applications
300MHz to 20000 GHz: for infrared spectrum; used for pointto point and multiple point application (line of sight)
Physical applications: Terrestrial microwavelong haul telecommunication service
(alternative to coaxial or optical fiber)
Propagation via towers located without blockage from trees,etc (towers less than 60 miles apart)
O i
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Overview
3
Monday, September 12, 2011
Basic concepts in communications
Understanding Networking.
Understanding Transmission Medium (Network
Cables)
Understanding Network Hardware
WAN and LAN
Understanding Network Protocols
Hubs
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Hubs
3
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A hub is the place where data converges from one or
more directions and is forwarded out in one or more
directions.
Seen in local area networks
Gateways
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Gateways
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A gateway is a network point that acts as an entranceto another network.
Routers
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Routers
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A router is a device or a software in a computer that
determines the next network point to which a packetshould be forwarded toward its destination.
Allow different networks to communicate with eachother
A router creates and maintain a table of the availableroutes and their conditions and uses this informationalong with distance and cost algorithms to determine thebest route for a given packet.
A packet will travel through a number of network points
with routers before arriving at its destination.
Bridge
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Bridge
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a bridge is a product that connects a local area
network (LAN) to another local area network that
uses the same protocol (for example, Ethernet or
token ring).
A bridge examines each message on a LAN,"passing" those known to be within the same LAN,
and forwarding those known to be on the other
interconnected LAN (or LANs).
What is the difference between?
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What is the difference between?
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Bridge: device to interconnect two LANs that use the
SAME logical link control protocol but may use
different medium access control protocols.
Router: device to interconnect SIMILAR networks,
e.g. similar protocols and workstations and servers Gateway: device to interconnect DISSIMILAR
protocols and servers, and Macintosh and IBM LANs
and equipment
Switches
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Switches
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Allow different nodes of a network to communicate
directly with each other.
Allow several users to send information over a
network at the same time without slowing each other
down.
Circuit Switching Technologies
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Circuit Switching Technologies
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Circuit switching is a dedicated communications path established
between two stations or multiple end points through nodes of the WAN Transmission path is a connected sequence of physical link between
nodes.
On each link, a logical channel is dedicated to the connection. Data
generated by the source station are transmitted along dedicated path as
rapidly as possible.
At each node, incoming data are routed or switched to the appropriate
outgoing channel without excessive delay. However, if data processing
is required, some delay is experienced.
Example of circuit switching above is the telephone networks.
Packet Switching Technologies
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Packet Switching Technologies
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Data are sent out in a sequence of small chucks, calledpackets.
Each packet, consisting of several bits is passed through thenetwork from node to node along some path leading from thesource to the destination
At each node along the path, the entire packet is received,
stored briefly, and then transmitted to the next node. At destination all individual packets are assembled together
to form the complete text and message from the source. Eachpacket is identified as to its place in the overall text forreassembly.
If packet errors occur, the packet is retransmitted.
Frame Relay Techniques
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Frame Relay Techniques
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Each packet included additional bits and each node performed
additional processing to insure reliable transmission. Frame relay has removed the overhead bits and additional processing.
It has become unnecessary to invoke these overhead checks andthereby enables higher capacity transmission rates.
Frame relay takes advantage of these high rates and low error rates.
Frame relay networks are designed to operate efficiently at user datarates of 2 Mb/s and higher. (packet switching originally designed witha 64 Kb/s data rate to the end user).
Frame relay achieves these higher rates by stripping out most of theoverhead involved with error control.
Asynchronous Transfer Mode (ATM)
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Asynchronous Transfer Mode (ATM)
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Evolution from frame relay and circuit switching.
Major differences: Frame relay uses variable length packets
called frames. ATM uses fixed length packets called
cells.
ATM provides little overhead for error control like frame
relay, and depends on inherent reliability of the transmissionsystem and on higher layers of logic in the end systems to
identify and correct errors.
ATM is designed to operate in range of 10s to 100 Mb/s
compared to frame relay (2 Mb/s)
ISDN and
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ISDN and
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Integrated services digital network (ISDN) was intended to
be a world wide public telecommunication network toreplace existing public telecommunication networks anddeliver a wide variety of services.
ISDN has standardized user interfaces, implemented a set ofdigital switches and paths supporting a broad range of traffictypes and providing a value added processing service
ISDN is multiple networks, but integrated to provide userwith single, uniform accessibility and world wideinterconnection.
Broadband ISDN Technology
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Broadband ISDN Technology
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First generation ISDN was narrowband, 64 Kb/s
channel of switching and circuit switchingorientations. Frame relay resulted from the ISDNnarrowband efforts.
Second generation is broadband ISDN. It supports
high data rates of 100 Mb/s and has a packetswitching orientation. ATM resulted from thebroadband ISDN efforts.
What is ethernet?
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What is ethernet?
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A group of standards for defining a local areanetwork that includes standards in cabling and the
structure of the data sent over those cables as well as
the hardware that connects those cables.
Independent of the network architecture
Network Interface Card (NIC)
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Network Interface Card (NIC)
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Every computer and most devices (e.g. a network
printer) is connected to network through an NIC. Inmost desktop computers, this is an Ethernet card (10
or 100 Mbps) that is plugged into a slot on the
computer motherboard.
How does Ethernet work?
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How does Ethernet work?
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Using MAC addresses to distinguish betweenmachines
What is a MAC Address?
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Media Access Control (MAC) Addressare thephysical address of any device.
The MAC address has two parts of 3 bytes long. The
first 3 bytes specify the company that made the NIC
(Network Interface Card) and the second 3 bytes arethe serial number of the NIC.
Overview
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5
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Basic concepts in communications
Understanding Networking.
Understanding Transmission Medium (Network
Cables)
Understanding Network Hardware
Understanding Network Protocols
Protocols of Computer Communications anN t k
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Networks
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Protocol are used for communication between computers in different
computer networks. Protocol achieves:
What is communicated between computers?
How it is communicated?
When it is communicated?
What conformance (bit sequence) between computers?
Key elements of a protocol are:
SYNTAC: Data format and signal levels
SEMANTICS: Control information for coordination and error handling
TIMING: Synchronization, speed matching, and sequencing
Examples of protocols:
WAN Protocol: TCP/IP LAN Protocol: Media Access Control; Contention; Token Passing
ISO/OSI Reference Model (1)
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( )
5
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Open Systems Interconnection
No one really uses this in the real world.
A reference model so others can develop detailed
interfaces.
The reference model defines 7 layers of functions
that take place at each end of communication and
with each layer adding its own set of special related
functions.
ISO/OSI Reference Model (2)
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( )
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How to transmit signal; codingHardware means of sending and receiving data on a carrier
Two party communication: Ethernet
Routing and Forwarding Address: IP
End-to-end control & error checking
(ensure complete data transfer): TCP
Establish/manage connection
ASCII Text, Sound (syntax layer)
File Transfer, Email, Remote Login
What is TCP/IP?
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Transmission Control Protocol (TCP)uses a set of rules to
exchange messages with other Internet points at theinformation packet level
Internet Protocol (IP)uses a set of rules to send and receive
messages at the Internet address level
TCP (example)
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p
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Web Server: serves HTML pages
TCP layer in the server divides the file into one or morepackets, numbers the packet, then forward packetsindividually to IP.
Note: each packet has the same destination IP address, itmay get routed differently through the network.
TCP (on the client) reassembles the individual packetsand waits until they have arrived to forward them as asingle file.
Connection-oriented protocol
IP
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Connectionless protocol (I.e. no established
connection between the end points that arecommunicating.)
Responsible for delivery the independently treated
packet !!!!
TCP responsible for reassembly.
Overview
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5
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Basic concepts in communications Understanding Networking.
Understanding Transmission Medium (Network
Cables)
Understanding Network Hardware
Understanding Network Protocols
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THANKS !COPYRIGHTS RESERVED
Monday, September 12, 2011