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Topic:-Mesh/Hybrid Topology Network
I.:-Networking
1.:-Introduction:- A network can be defined as a group of computers and other
devices connected in some ways so as to be able to exchange data. Each of the
devices on the network can be thought of as a node; each node has a unique address.
Addresses are numeric quantities that are easy for computers to work with, but not for
humans to remember.
Example: 204.160.241.98
Some networks also provide names that humans can more easily remember than
numbers.
Example: www.javasoft.com, corresponding to the above numeric address.
…..
Fig.:-1.1
1.1:- Addressing:-
1.1.1:- Internet address:- Consists of 4 bytes separated by periods.
Example: 136.102.233.49
The R first bytes (R= 1,2,3) correspond to the network address;
The remaining H bytes (H = 3,2,1) are used for the host machine.
1.1.2:- InterNIC Register:-Organization in charge of the allocation of the
address ranges corresponding to networks.
Criteria considered:
 Geographical area (country)
 Organization, enterprise
 Department
 Host
1.1.3:- Domain Name System (DNS):- Mnemonic textual addresses are
provided to facilitate the manipulation of internet addresses. DNS servers are
NIC NIC NIC
addr 1 addr 1 addr 1

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responsible for translating mnemonic textual Internet addresses into hard numeric
Internet addresses.
1.1.4:- Ports:- An IP address identifies a host machine on the Internet. An IP
port will identify a specific application running on an Internet host machine. A port is
identified by a number, the port number. The number of ports is not functionally
limited, in contrast to serial communications where only 4 ports are allowed. There
are some port numbers which are dedicated for specific applications.
Table :-1.1.4.1:- Specific Application Port Number
1.2:- Data Transmission:- In modern networks, data are transferred using
packet switching. Messages are broken into units called packets, and sent from one
computer to the other. At the destination, data are extracted from one or more packets
and used to reconstruct the original message. Each packet has a maximum size, and
consists of a header and a data area. The header contains the addresses of the source
and destination computers and sequencing information necessary to reassemble the
message at the destination.
packet
header data
1001….101 00010000111…000000110001100
1.3:- Types of Networks:- There are two principle kinds of networks:
I:-Wide Area Networks (WANs).
II:-Local Area Networks (LANs).
Applications Port Numbers
HTTP 80
FTP 20 and 21
Gopher 70
SMTP(e-mail) 25
POP3(e-mail) 110
Telnet 23
Finger 79

4
1.3.1:- Wide Area Network(WANs):- Cover cities, countries, and
continents. Based on packet switching technology Examples of WAN technology:
Asynchronous Transfer Mode (ATM), Integrated Services Digital Network (ISDN).
1.3.2:- Local Area Network (LANs):- Cover buildings or a set of closely
related buildings. Examples of LAN technology: Ethernet, Token Ring, and Fibber
Distributed Data Interconnect (FDDI).
Ethernet LANs: based on a bus topology and broadcast communication
Token ring LANs: based on ring topology
FDDI LANs: use optical fibbers and an improved token ring mechanism
based on two rings flowing in opposite directions.
Fig.:-
1.3.2.1:-LANs
Network connectivity type Speed Transmission time
for 10 Mbytes
(Telephone)dail-up modem 14.4 Kbps 90 Min
ISDN modem 56/128 Mbps 45/12 Min
T1 connection 1.54 Mbps 50s
Ethernet 10 Mbps 9s
Token Ring 4/16 Mbps
Fast Ethernet 100 Mbps
FDDI 100 Mbps
Gigabit Ethernet 1 Gbps
ATM 25Mbps/2.4Gbps
Table:- 1.3.2.1:-WANs And LANs Network Connetctivity,Speed And
Transmission Time

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1.4:- Interconnection:- Networks of low capacity may be connected
together via a backbone network which is a network of high capacity such as a FDDI
network, a WAN network etc. LANs and WANs can be interconnected via T1 or T3
digital leased lines According to the protocols involved, networks interconnection is
achieved using one or several of the following devices:
 Bridge: a computer or device that links two similar LANs based on the same
protocol.
 Router: a communication computer that connects different types of networks
using different protocols.
 B-router or Bridge/Router: a single device that combines both the functions of
bridge and router.
 Gateway: a network device that connects two different systems, using direct
and systematic translation between protocols.
Fig.:-1.4.1:-Inerconnection
1.5:- Network Topology Diagram:- The specification of the network
topology diagram requires the definition of the characteristics and entities underlying
the network: Geographical locations of the different components or subnets involved
in the network. Description of the LAN topology. Description of the WAN topology.
Description of the network connectors such as routers, bridges,repeaters, and
gateways.

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2. :- Protocols:- Define the rules that govern the communications between two
computers connected to the network. Roles: addressing and routing of messages, error
detection and recovery, sequence and flow controls etc. A protocol specification
consists of the syntax, which defines the kinds and formats of the messages
exchanged, and the semantic, which specifies the action taken by each entity when
specific events occur.
Example: HTTP protocol for communication between web browsers and servers.
Request For Comments (RFC): specifications of the protocols involved in Internet
Communications. Example: Sample of RFC 821 describing communications between
SMTP server and client. Protocols are designed based on a layered architecture such
as the OSI reference model. Each entity at a layer n communicates only with entities
at layer n-1. The data exchanged, known as Protocol Data Unit (PDU), goes back and
forth through the layers, each layer adds or removes its own header and vice-versa.
Therefore a layer n PDU may become a layer n-1 data.
Fig.:- Network Topology Diagram
3. :- Protocol Layers:-
3.1:- The OSI (Open Systems Interconnection) Data Model:- ISO
standard for computer networks design and functioning. Involves at least 7 layers,
each playing a specific role when applications are communicating over the net.
During the sending process, each layer (from top to down) will add a specific header

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to the raw data. At the reception, headers are eliminated conversely until the data
arrived to the receiving application.
Fig.:-3.1:- OSI Layers
1.:- Physical layer: ensures a safe and efficient travel of data; consists of
electronic circuits for data transmission etc.
2.:- Data link layer: in charge of data encapsulation under the form of packets and
their interpretation at the physical layer.
3.:- Network layer: in charge of packets transmission from a source A to a
destination B.
4.:- Transport layer: in charge of the delivery of packets from a source A to a
destination B
5.:- Session layer: in charge of the management of network access.
6.:- Presentation layer: determines the format of the data transmitted to
applications, data compressing/decompressing, encrypting etc.
OSI Layers
Application layer
(applications connected to the network)
Presentation layer
(provides standard data representations for applications)
Session layer
(manages sessions among applications)
Transport layer
(provides end-to-end errors detection and correction)
Network layer
(handles connection to the network by the higher layers)
Data-link layer
(provides safe communication of data over the physical network)
Physical layer
(defines the physical characteristics of the network)

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Network layer
(provides routines allowing access to the physical network)
Application layer
(applications and processes running on the network)
Transport layer
(provides end-to-end data delivery services)
Internet layer
(makes datagrams and handles data routing)
7.:- Application layer: contains the applications which are used by the end-user,
such as Java, Word etc.
3.2:-The TCP/IP Model:--Consists of only 4 layers: application, transport,
internet and network.
Layers:-
Fig.:- 3.2.1:-Layers
1.:- Network layer:- Provides the same functionality as the physical, the data link
and network layers in the OSI model. Mapping between IP addresses and network
physical addresses. Encapsulation of IP datagrams, e.g packets, in format
understandable by the network.
2.:- Internet layer:- Lies at the heart of TCP/IP. Based on the Internet Protocol
(IP), which provides the frame for transmitting data from place A to place B.
3.:- Transport layer:- Based on two main protocols:
I:-TCP (Transmission Control Protocol)
II:-UDP (User Datagram protocol)
4.:- Application layer:- Combines the functions of the OSI application,
presentation, and
5.:- Session layer:- Protocols involved in this layer: HTTP, FTP, SMTP etc.

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4. Networks Interconnection/Internet:-
4.1:- Concept of Network Interconnection:- First implemented in the
Defense Advanced Research Project Agency Network (Arpanet), in 1966 in USA.
Consists of connecting several computer networks based on different protocols
Requires the definition of a common interconnection protocol on top the local
protocols. The Internet Protocol (IP) plays this role, by defining unique addresses for
a network and a host machine.
Fig.:-4.1.1:-Network Interconnetction/Internet
4.2:- Internet Protocol (IP):-
4.2.1:- Overview:- The IP protocol provides two main functionality:
 Decomposition of the initial information flow into packets of standardized
size, and reassembling at the destination.
 Routing of a packet through successive networks, from the source machine to
the destination identified by its IP address.
Transmitted packets are not guaranteed to be delivered (datagram protocol). The IP
protocol does not request for connection (connectionless) before sending data and
does not make any error detection. Functions Decompose the initial data (to be sent)
into datagrams. Each datagram will have a header including, the IP address and the
port number of the destination. Datagrams are then sent to selected gateways, e.g IP
routers, connected at the same time to the local network and to an IP service provider
P1
P2
P4
P3
IP

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network. Datagrams are transferred from gateways to gateways until they arrived at
their final destination.
Fig.:-4.2.1.1:-A IP(Internet Protocols) View
4.2.2:- Structure of an IP packet:- The fields at the beginning of the
packet, called the frame header, define the IP protocol’s functionality and limitations.
32 bits are allocated for encoding source and destination addresses (32 bits for each of
these address fields). The remainder of the header (16 bits) encodes various
information such as the total packet length in bytes. Hence an IP packet can be a
maximum of 64Kb long.
0 10 12 16 20 24
Header
Checksum
Source address
Destination address
Options
Data
4.3:- Transmission Control Protocol (TCP):-
4.3.1:- Overview: TCP provides by using IP packets a basic service that does
guarantee safe delivery:
 error detection
 safe data transmission
 assurance that data are received in the correct order
packet 1
Routers
packet 2 Receiver
Sender

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Before sending data, TCP requires that the computers communicating establish a
connection (connection-oriented protocol).
Fig.:-4.3.1.1:- A TCP View
TCP provides support for sending and receiving arbitrary amounts of data as one big
stream of byte data (IP is limited to 64Kb). TCP does so by breaking up the data
stream into separate IP packets. Packets are numbered, and reassembled on arrival,
using sequence and sequence acknowledge numbers. TCP also improves the
capability of IP by specifying port numbers.
→ There are 65,536 different TCP ports (sockets) through which every TCP/IP
machine can talk.
4.3.2:- Structure of a TCP packet:-
0 2 4 8 12 20
Source Port
Destination Port
Sequence No.
Sequnece Ack No.
Misc. Header
Data
4.4:- User Datagram Protocol (UDP):-
4.4.1:- Overview:- Datagram protocol also built on top of IP. Has the same
packet-size limit (64Kb) as IP, but allows for port number specification. Provides also
65,536 different ports. Hence, every machine has two sets of 65,536 ports: one for
TCP and the other for UDP. Connectionless protocol, without any error detection

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facility. Provides only support for data transmission from one end to the other,
without any further verification. The main interest of UDP is that since it does not
make further verification, it is very fast. Useful for sending small size data in a
repetitive way such as time information.
4.5:- Internet Application Protocols:- On top of TCP/IP, several
services have been developed in order to homogenize applications of same nature:
-FTP(File Transfer Protocol):- allows the transfer of collection of files between two
machines connected to the Internet.
-Telnet(Terminal Protocol):- allows a user to connect to a remote host in terminal
mode.
-NNTP(Network News Transfer Protocol):- allows the constitution of
communication groups (newsgroups) organized around specific topics.
-SMTP(Simple Mail Transfer Protocol):- defines a basic service for electronic
mails.
-SNMP(Simple Network Management Protocol):- allows the management of the
network.
Fig.:-4.5.1:-Internet Application Protocols
II:-Network Topology:-
1:-Introduction :- Abstract: The geometrical arrangement of computer
resources, remote devices and communication facilities is known as Network
structure or Network topology. A computer network is comprised of nodes and links,
TCP/UDP
IP
FTP Telnet SMTP SNMP
Ethernet Arpanet Token Ring

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1 • Bus Topology
2 • Ring Topology
3 • Star Topology
4 • Tree Topology
5 • Mesh/Hybrid Topology
a node is the end point of any branch in a computer, a terminal device, workstation or
interconnecting equipment facility.
A link is a communication path between two nodes. The terms “circuit” and
“Channel” are frequently used as synonyms for the link.
There are different types of the topologies like bus, ring, tree, mesh etc. However, we
will consider five basic network structures- topology.
Keywords: How topology use, Advantages, Disadvantages
Network Topology is the study of the arrangement or mapping of the elements (links,
nodes, etc.) of a network interconnection between the nodes.
Topologies can be physical or logical. Physical Topology means the physical design
of a network including the devices, location and cable installation. Logical Topology
refers to the fact that how data actually transfers in a network as opposed to its design.
1.1:-Some of the most common network topologies are:-
2:-Bus Topology:- This structure is very popular for local area networks. In
this structure or topology, a single network cable runs in the building or campus and
all nodes are linked along with this communication line with two endpoints called the
bus or backbone as show figure.
Fig.:-2.1:- Structure of Bus Topology Network

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By this type of topology, if one node goes faulty all nodes may be affected as all
nodes share the same cable for the sending and receiving of information. The cabling
cost of bus systems is the least of all the different topologies. Each end of the cable is
terminated using a special terminator.
[A]. Advantages:-
− Reliable in very small networks as well as easy to use and understand.
− Requires least amount of cable to connect the computers (nodes) together and
therefore is less expensive than other cabling arrangements.
− It's easy to extend, Two cables can be easily joined with a connector, making a
longer cable for more computers to join the network.
− A repeater can also be used to extend a bus configuration.
[B]. Disadvantages:-
− Heavy network traffic can slow a bus considerably because any computer can
transmit at any time. But networks do not Coordinate when information is sent.
Computer interrupting each other can use a lot of bandwidth.
− Each connection between two cables weakens the electrical signal.
− The bus configuration can be difficult to find and can cause the whole networks to
stop functioning.
3:-Ring Topology:- This is yet another structure for local area networks. In
this topology, the network cable passes from one node to another until all nodes are
connected in the form of a loop or ring. There is a direct point-to-point link between
two neighboring nodes (the Next and the Previous). These links are unidirectional
which ensures that transmission by a node traverses the whole ring and comes back to
the node, which made the transmission as shown in figure.
Fig.:-2.1:- Structure of Ring Topology Network

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Information travels around the ring from one node to the next. Each packet of data
sent to the rink is prefixed by the address of the station to which it is being sent. When
a packet of data arrives, the node checks to see if the packet address is the same as its
own, if it is, it grabs the data in the packet. If the packet does not belong to it, it sends
the packet to the next node in the ring. Faulty nodes can be isolated from the ring.
When the workstation is powered on, it connects itself to the ring. When power is off,
it disconnects itself from the ring and allows the information to bypass the node. The
most common implementation of this topology is token ring. A break in the ring
causes the entire network to fail. Individual nodes can be isolated from the ring.
[A]. Advantages:-
− Ring networks offer high performance for a small number of workstations or for
larger networks where each station has a similar workload.
− Ring networks can span longer distances than other types of networks.
− Ring networks are easily extendable.
− Unlike Bus topology, there is no signal loss in Ring topology because the tokens are
data packets that are re-generated at each node.
− Relatively expensive and difficult to install
− Failure of one computer on the network can affect the whole network.
− It is difficult to find fault in a ring network.
− Adding or removing computers can disrupt the network.
− It is much slower than an Ethernet network under normal load.
4:-Star Topology:- Star topology uses a central hub through which, all
components are connected. In a Star topology, the central hub is the host computer,
and at the end of each connection is a terminal as shown in Figure.
Fig.:-3.1:-Structure of Star Topology Network

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Nodes communicate across the network by passing data through the hub. A star
network uses a significant amount of cable as each terminal is wired back to the
central hub, even if two terminals are side by side but several hundred meters away
from the host. The central hub makes all routing decisions, and all other workstations
can be simple.
An advantage of the star topology is that failure, in one of the terminals does not
affect any other terminal; however, failure of the central hub affects all terminals.
This type of topology is frequently used to connect terminals to a large time-sharing
host computer.
[A]. Advantages:-
− It is more reliable (if one connection fails, it does not affect others)
− The center of a star network is a good place to diagnose network faults and if one
computer fails whole network is not disturbed. Hub detects the fault and isolates the
faulty computer.
− It is easy to replace, install or remove hosts or other devices, the problem can be
easily detected-It is easier to modify or add a new computer without disturbing the
rest of the network by simply running a new line from the computer to the central
location and plugging it to the hub.
− Use of multiple cable types in a same network with a hub.
− It has good performance
− It is expensive to install as it requires more cable, it costs more to cable a star
network because all network cables must be pulled to one central point, requiring
more cable length than other networking topologies.
− Central node dependency, if central hub fails, the whole network fails to operate.
− Many star networks require a device at the central point to rebroadcast or switch the
network traffic.
5:-Tree Topology:- The most common structure or topology known as Tree
topology, Tree topology is a LAN topology in which only one route exists between
any two nodes on the network. The pattern of connection resembles a tree in which all
branches spring from one root.

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Fig.:-2.1:- Structure of Tree Topology Network
Tree topology is a hybrid topology, it is similar to the star topology but the nodes are
connected to the secondary hub, which in turn is connected to the central hub. In this
topology group of star-configured networks are connected to a linear bus backbone.
[A]. Advantages:-
− Installation and configuration of network are easy.
− The addition of the secondary hub allows more devices to be attached to the central
hub.
− Less expensive when compared to mesh topology.
− Faults in the network can be detected traces.
− Failure in the central hub brings the entire network to a halt.
− More cabling is required when compared to the bus topology because each node is
connected to the central hub.
6:-Mesh/Hybrid Topology:-
6.1:-Introduction To Mesh/Hybrid Topology:- Devices are connected
with many redundant interconnections between network nodes. In a well-connected
topology, every node has a connection to every other node in the network. The cable
requirements are high, but there are redundant paths built in. Failure in one of the
computers does not cause the network to break down, as they have alternative paths to
other computers.

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Fig.:-5.1.1:- Mesh Topology Network
Mesh topologies are used in critical connection of host computers (typically telephone
exchanges). Alternate paths allow each computer to balance the load to other
computer systems in the network by using more than one of the connection paths
available.
A fully connected mesh network therefore has no (n-1) /2 physical channels to link n
devices. To accommodate these, every device on the network must have (n-1)
input/output ports.
[A]. Advantages
− Yield the greatest amount of redundancy in the event that one of the nodes fails
where network traffic can be redirected to another node.
− Point-to-point link makes fault isolation easy.
− Privacy between computers is maintained as messages travel along dedicated path.
− Network problems are easier to diagnose.
[B]. Disadvantages
− The amount of cabling required is high.
− A large number of I/O (input/output) ports are required.
6.2:- Mesh/Hybrid Topology:-
A local area network that employs either a full mesh topology or partial mesh
topology .
Full mesh topology- each node is connected directly to each of the others.
Partial mesh topology- some nodes are connected to all the others, but some of
them are only connected to nodes with which they exchange the most data.

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6.3:- History of Mesh/Hybrid Topology:-
Originally sponsored by the Department of Defense for military use.
Goal was to provide packet-switched network in mobile elements of a
battlefield in an infra-structureless environment.
Used a combination of ALOHA and CSMA and distance vector routing.
Note:-1972- Packet Radio Network.
Wanted soldiers, tanks, aircraft, etc. to be the nodes in the network.
6.4:- Full Mesh Topology:-
Every node has a circuit connecting it to every other node in the network.
Yields greatest redundancy, so if one node fails, network traffic can be
redirected to any of the other nodes.
Usually reserved for backbone networks since it is very expensive.
Fig.5.3.1:-Structure of Mesh/Hybrid Topology Network
6.5:- Partial Mesh Topology:-
Some nodes are organized in a full mesh scheme but others are only connected
to 1 or 2 in the network.
Common in peripheral networks connected to a full meshed backbone.
Less expensive to implement.
Yields less redundancy.

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Fig.:-5.4.1:-Structure of Mesh/Hybrid Topology Network
6.6:- Wired Mesh:-
It is possible to have a fully wired mesh network, however this is very
expensive
Advantages:-
 Reliable
 Offers redundancy
Disadvantages:-
 Expensive- large number of cables and connections required
Note:- Not really used in practice much, since the whole benefit of using mesh is in
the wireless.
6.7:- Wireless Mesh:-
Definition- a wireless co-operative communication infrastructure between
multiple individual wireless tranceivers that have Ethernet capabilities.
Can either be centralized for highly scalable applications, or can be
decentralized.
Advantages:-
Reliable- each node is connected to several others; when a node fails
its neighbors find other routes.
Scalable- capacity can be added simply by adding nodes.

21
Nodes act as repeaters to transmit data from nearby nodes to peers too
far away to reach- this results in a network that can span large
distances over rough terrain.
Each node only transmits as far as the next node.
Note:-Thought this was interesting application of wireless.
Robot that uses a wireless mesh network to see its environment and interact with it.
Extension of CalMesh- ad-hoc network of lightweight, small reconfigurable nodes
that self-organize to form a wireless mesh network.
Upcoming version will enable mobile to mobile mesh networking.
6.8:-How Does It Work?:-
Data hops from one device to another until it reaches its destination.
Each device communicates its routing information to every device it connects
with.
Each device then determines what to do with received data- pass it on or keep
it.
6.9:-Routing:-
When a node needs a connection with another node and a route doesn’t exist it
sends a request to its “mother” node
This node then forwards the message to its “mother” node and so on until the
original node is connected at the root to the node it wanted.
Next the algorithm tries to “cut corners” to optimize the path.
 Each node on the route floods its neighbors with routing requests.
 When a faster route is found, the unused part of the previous route is
erased and flooding ceases on that route.
6.10:-Advantage of Mesh/Hybrid Toplogy:-
Produces fairly good routes while reducing the number of messages required
to keep the network connected.
Uses only small amounts of memory at each node.
The network has a reliable way to establish that a node is not in the network.
6.11:-Advantage of Mesh/Hybrid Toplogy:-
Central “mother” nodes have an extra burden.
Eventually ceases to be scalable.

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Link propagation time establishes a limit on the speed the network can find its
root.
May use more power and bandwidth than other link-state protocols.
7:-Conclusion of Report:-
In this paper we have to study the different types of the topologies like Bus Topology,
Ring Topology, Star Topology, Mesh Topology and Tree Topology.
In this paper we have considered above five topology uses and its merits and demerits
that will study will help to know that which structure or topology is best for which
organization or business. We have to study the topology and finally we have to find
the fact that all topologies are alternate options for business like that Bus Topology is
use full for small network but its some demerits so its alternate option is Ring
Topology. So finally, we can say that all topologies have some extra and different
feature are available from other topology and that features are making it special from
other topology.
-:Refrence:-
1. Research Paper of Kartik Pandya ,Lecturer in Sikkim Manipal
University (S.M.U), India On (Network Structure OR Topology At
www.ijarcsms.com
2. http://www.sis.pitt.edu/~icucart/networking_basics/networking_topolo
gy.html
3. http://www.geocities.com/SiliconValley/Monitor/3131/ne/1nenotes.ht
ml#Network%20Topologies
4. Internet Resources.

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