If we apply 120-volt AC, 60-hertz power to the primary of a power transformer with its secondary open, a very small current will flow through the primary winding. Only a small quantity primary current will flow because the inductive reactance of the primary winding is very high. However, if a load is then placed on the secondary winding
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Showing posts with label electronics tutorials. Show all posts
Showing posts with label electronics tutorials. Show all posts
TCP/IP Protocol
The TCP/IP protocol suite is used in internet was developed prior to OSI model. Therefore the layers used in Transmission control protocol/Inter networking protocol are different from layers in OSI model.
The TCP/IP protocol is made of five layers; physical,data link, network, transport and application layer. The first four layers provide the physical standards, network interface, inter-networking and transport functions that correspond to first four layers of OSI model.
In TCP/IP protocol the top three layers are shown by single application layer. The different modules in TCP/IP suite are relatively independent and changes as per the need of system. The term hierarchical means top layer is supported by below layers.
At transport layer TCP/IP defines the transmission control protocol(TCP) and user datagram protocol(UDP)
At network layer the inter-networking protocol is defined(IP). Some data movement protocols are also supported on this layer.
The TCP/IP protocol is made of five layers; physical,data link, network, transport and application layer. The first four layers provide the physical standards, network interface, inter-networking and transport functions that correspond to first four layers of OSI model.
In TCP/IP protocol the top three layers are shown by single application layer. The different modules in TCP/IP suite are relatively independent and changes as per the need of system. The term hierarchical means top layer is supported by below layers.
At transport layer TCP/IP defines the transmission control protocol(TCP) and user datagram protocol(UDP)
At network layer the inter-networking protocol is defined(IP). Some data movement protocols are also supported on this layer.
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Application Layer
The application layer enables the user to access the network. It provides user interface and support foe services such as mail,remote file access and transfer, shared database management. It relates between presentation layer and user.
The services provided by application layer are :
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The services provided by application layer are :
- Network Virtual terminal; It is a software version of a physical terminal and allows a user to log on to a remote host.
- File transfer,Access and Management; It provides a user to access and transfer files in a remote computer.
- Mail Services; it provides the email forwarding and storage.
- Directory service; It provides distributed database sources and access for global information.
Presentation Layer
The presentation layer is concerned with the syntax and semantics of information exchanged between two system.
The presentation layer has following responsibilities;
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The presentation layer has following responsibilities;
- Translation; The process of changing information in two systems is usually in the form of character strings,numbers and so on. The information is changed into a bit stream by encoding on presentation layer.
- Compression; Data compression reduces the number f bits to be transmitted. It is important mostly in the transmission of multimedia such as text,audio and video.
Session Layer
The session layer is te network dialog controller. It establish,maintain and synchronize the interaction between communicating systems.
The responsibilities of session layer are:
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The responsibilities of session layer are:
- The session layer allows two systems to enter into a dialog. It allows the communication between the two in half or full duplex. It called dialog control.
- It make synchronization checkpoints into a stream of data. The checkpoints can be specified by time limit or data limit.
Transport Layer
The transport layer is responsible for source to destination delivery of the entire message. The transport layer ensures that the whole message arrive intact and in order and check all the packets relation to each other. Also check the error control and flow control at source to destination level.
For additional security, network layer may create the connection between two end ports. It involves the etablishment, data transfer and connection release.
Transport layer have following responsibilities;
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For additional security, network layer may create the connection between two end ports. It involves the etablishment, data transfer and connection release.
Transport layer have following responsibilities;
- Service point addressing; As compters run many programs at the same time. So here source to destination delivery is not from one computer to other but it is froma specific program on one computer to a specific program on the other. Therefore transport layer header must include a service point address or port address.The transport layer gets the entire message to the correct program running on computer.
- A mesasge is divided into transmittable segmentrs, each segment contains a sequence number. These number used in reassembling.
- The transport layer can be connectionless or connection oriented. In connectionless it simply deliver packet to network layer at destination but in connection oriented it makes connection with the transport layer and then deliver packets.
- Like data link layer it is responsible for flow control. Here flow control is end to end not on a single link.
- Like data link layer it is responsible for error control. It makes sure that the entire message is delivered correctly at the destination without any error.
Network Layer
The network layer is responsible for the source to destination delivery of a packet possibly across multiple networks. It also determines the delivery of packet from origin to destination in a network.
If two systems connected to same network then network layer is not needed. But for different network from source to destination delivery it is needed.
Some responsibilties of network layer are below:
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If two systems connected to same network then network layer is not needed. But for different network from source to destination delivery it is needed.
Some responsibilties of network layer are below:
- For different networks the network layer adds a header to the packet coming from upper layer including logical address of sender and receiver.
- When the independent networks are connected together to create an internetwork, the connecting devices ( routers and gateways ) route the packets to their destination.
Data Link Layer
The data link layer transforms the physical layer a a raw transmission facility to a reliable link and is resposible for nod eto node delivery. It makes the physical layer error free for the network layer.
This layer includes the following responsibilities :
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This layer includes the following responsibilities :
- It divides the stream of bits received from network layer into manageable data units called frames.
- If frames are to be distributed to different systems on network, it adds a header to the frame to define the physical address of the sender(source address) and/or receiver(destination address) of frame.
- It also control that the data rate absorbed by reveiver must match the data rate at which is sent by sender called flow control.
- It also control the retransmitting of data if any frame is lost or damaged and the duplication of frames called error control.
- If two or more devices are connected to a same link. Then data link layer determines that which device has control over the link at any given time.
Physical Layer
The physical layer coordinate the functions required for the transmission of a bit stream over a physical medium. It deals with the interface and transmission medium. It is concerned with the following:
- The physical characteristics of interface between medium and devices.
- At physical layer data must be in 0 and 1 (bit form). So it define the encoding.
- Tha data rate is defined that how many bits per second are sent.
- The sender and receiver must be synchoronised at bit level.
- The line configuration is also concerend with physical layer. It may be point to point or multipoint.
- The topology used for the network is also concerned with the physical layer.e.g; star,mesh,ring etc.
- The transmission mode is also concerned with physical layer. It may be simplex,half or full duplex.
Categories of Networks
There are three primary types of networks including local area networks, metropolitan area networks and wide area networks. Here we differentiate them by their size, ownership, distance and structure.
Local Area Network (LAN) :
A local area network is a private network having links of devices within a campus,building or office. A LAN can have two or more systems connected or devices i.e printers in a office. It also depend on the technology used in the networking.
In LAN we basically share data or sometimes hardware. The restrictions can be used on some particular software or hardware for the usage, by the number of users. It also depends which topology and transmission medium is used.
LANs have data rate from 4 to 6 Mbps range. Now a days its increasing and may be 100 Mbps depending on the speed of systems.
Metropolitan Area Network (MAN) :
A metropolitan area network is more widely can be used. It can be used in a entire city. It may be a single network or it can be combination of some LANs. A MAN can be used for a company having many offices in a city.
A MAN is owned by a company. Some service provider can also provide the MAN to a company by switched multi megabit data services (SMDS).
Wide Area Network (WAN) :
A wide area network provides a long distance transmission of data. It may be overr large geographical areas thay may be acountry, a continent or whole world.
A WAN can use public or private communication devices or usually in combination. It can be on unlimited number of miles.
Internetworks:
When two or more networks are connected, they become an internetwork or internet. The networks are connected by internetworking devices i.e routers,gateways.
The term internet is a generic term used to mean an interconnection of networks.
The Internet is the name of a specific worldwide network.
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Local Area Network (LAN) :
A local area network is a private network having links of devices within a campus,building or office. A LAN can have two or more systems connected or devices i.e printers in a office. It also depend on the technology used in the networking.
In LAN we basically share data or sometimes hardware. The restrictions can be used on some particular software or hardware for the usage, by the number of users. It also depends which topology and transmission medium is used.
LANs have data rate from 4 to 6 Mbps range. Now a days its increasing and may be 100 Mbps depending on the speed of systems.
Metropolitan Area Network (MAN) :
A metropolitan area network is more widely can be used. It can be used in a entire city. It may be a single network or it can be combination of some LANs. A MAN can be used for a company having many offices in a city.
A MAN is owned by a company. Some service provider can also provide the MAN to a company by switched multi megabit data services (SMDS).
Wide Area Network (WAN) :
A wide area network provides a long distance transmission of data. It may be overr large geographical areas thay may be acountry, a continent or whole world.
A WAN can use public or private communication devices or usually in combination. It can be on unlimited number of miles.
Internetworks:
When two or more networks are connected, they become an internetwork or internet. The networks are connected by internetworking devices i.e routers,gateways.
The term internet is a generic term used to mean an interconnection of networks.
The Internet is the name of a specific worldwide network.
Transmission Mode
The direction of a signal between two devices is defined by a transmission mode.
Or
The transmission mode defines the direction of a signal between two devices.There are three types of transmission mode given as below;
Simplex Mode:
In the simplex mode the communication is unidirectional. Only one can send data and other can receive. No any other possibility is available. A remote is an example of simplex mode.
Half Duplex Mode:
In half duplex mode both devices can send and receive data, but not at the same time. At a time one device send data and other receives. Walkie talkie is an example of half duplex mode.
Full Duplex Mode:
In full duplex mode both devices can send and receive data at the same time. It has two way traffic at the same time. The telephone network is an example of full duplex mode.
Or
The transmission mode defines the direction of a signal between two devices.There are three types of transmission mode given as below;
Simplex Mode:
In the simplex mode the communication is unidirectional. Only one can send data and other can receive. No any other possibility is available. A remote is an example of simplex mode.
Half Duplex Mode:
In half duplex mode both devices can send and receive data, but not at the same time. At a time one device send data and other receives. Walkie talkie is an example of half duplex mode.
Full Duplex Mode:
In full duplex mode both devices can send and receive data at the same time. It has two way traffic at the same time. The telephone network is an example of full duplex mode.
Network Criteria
For an effecient and effective networking the following criteria is most important.
Performance:
The performance depends on many factor some are discussed below:
Number of Users:
A large number of users on a network can slow its reponse time if it is designed for heavy traffic loads. In peak times on a certain network can slow its performance.
Transmission Medium:
The transmission medium used for the network also a main factor for its performance. As data has to travel on it. It can be fibre optics for a faster transfer of data.
Hardware:
The hardware used in networking affect the speed and capacity of transmission. A high computer with big storage will perform better.
Software:
The software used for running applications and data processig at sender reciever end and intermediary nodes also effects the performance of the network.
Reliability:
Rliability of a network on the followings;
Frequency of Failure:
All networks fail occasionally. But a network that fails often have little value to a user.
Recovery Time:
The time taken to restore itself after the failure is recovery time. The network quickly restores is more useful than the other takes much time.
Catastrophe:
The network must be protected by fire,earthquake or theft. There may be a system for back up of network software.
Security:
Network security isues include unauthrized access and viruses.
Unauthorized Access:
On a network there may be sensitive data, therfore it must be protected by an unauthorized access. It may be user identification and password or at higher level it can be encryption techniques.
Viruses:
As network can be accessed at many points, it may have computer virus. A virus is a code that damages the system. A good network must have the virus protection by hardware or software based.
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Performance:
The performance depends on many factor some are discussed below:
Number of Users:
A large number of users on a network can slow its reponse time if it is designed for heavy traffic loads. In peak times on a certain network can slow its performance.
Transmission Medium:
The transmission medium used for the network also a main factor for its performance. As data has to travel on it. It can be fibre optics for a faster transfer of data.
Hardware:
The hardware used in networking affect the speed and capacity of transmission. A high computer with big storage will perform better.
Software:
The software used for running applications and data processig at sender reciever end and intermediary nodes also effects the performance of the network.
Reliability:
Rliability of a network on the followings;
Frequency of Failure:
All networks fail occasionally. But a network that fails often have little value to a user.
Recovery Time:
The time taken to restore itself after the failure is recovery time. The network quickly restores is more useful than the other takes much time.
Catastrophe:
The network must be protected by fire,earthquake or theft. There may be a system for back up of network software.
Security:
Network security isues include unauthrized access and viruses.
Unauthorized Access:
On a network there may be sensitive data, therfore it must be protected by an unauthorized access. It may be user identification and password or at higher level it can be encryption techniques.
Viruses:
As network can be accessed at many points, it may have computer virus. A virus is a code that damages the system. A good network must have the virus protection by hardware or software based.
Distributed Processing
In a network a task is divided into multiple computers using multiple processing. Instead of a single large machine for different processes, many computers are used and following advantages can be gained by using distributed processsing.
Security/Encapsulation:
A system designer can limit the interaction of a user to an interface. for example in banks, the particular use only can see his own account not the whole bank data or accounts.
Distributed Databases:
A single system can not store the data of whole network. Therefore world wide web provide the access to information stored or available on the Internet.
Faster Problem Solving:
Different computers working on a problem can solve it earlier than a single computer solving it.
Security through Redundancy:
Multiple computers running the same program at the same time can provide security through redundancy. In space three computers runs the same application at a time so if one fails then other can override it.
Collaborative Processing:
Multiple computers and users can interact on a task. In network games each player see the action and effect of all others on the application running.
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Security/Encapsulation:
A system designer can limit the interaction of a user to an interface. for example in banks, the particular use only can see his own account not the whole bank data or accounts.
Distributed Databases:
A single system can not store the data of whole network. Therefore world wide web provide the access to information stored or available on the Internet.
Faster Problem Solving:
Different computers working on a problem can solve it earlier than a single computer solving it.
Security through Redundancy:
Multiple computers running the same program at the same time can provide security through redundancy. In space three computers runs the same application at a time so if one fails then other can override it.
Collaborative Processing:
Multiple computers and users can interact on a task. In network games each player see the action and effect of all others on the application running.
Hybrid Topology
Hybrid topology is the combination of using diffrent topologies with one as a backbone.
For example, a tree topology used as a back bone and secondry ring topology is used. So here the tree topology is backbone of ring topology and controlling the traffic and communication between the devices of all ring topolgy and may also attached devices in the tree topology itself.
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For example, a tree topology used as a back bone and secondry ring topology is used. So here the tree topology is backbone of ring topology and controlling the traffic and communication between the devices of all ring topolgy and may also attached devices in the tree topology itself.
Ring Topology
In a ring topology each device has a dedicated point to point line configuration only with the two devices on either side of it. A signal trevels in one direction fron device to device untill it reaches the destination. Each device have a repeater which is used to boost the signal.
Advantages:
1. Easy installation and reconfiguration.
2. Easy to remove a device by removing two cables.
3. Fault locatingand isolation is easy.
Disadvantages:
1. Unidirectional traffic can be a disadvantage.
2. The break in the ring dtops all the communication of network.
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Advantages:
1. Easy installation and reconfiguration.
2. Easy to remove a device by removing two cables.
3. Fault locatingand isolation is easy.
Disadvantages:
1. Unidirectional traffic can be a disadvantage.
2. The break in the ring dtops all the communication of network.
Bus Topology
In bus topology multi point line configuration is used. One long cable acts as a backboneto link all the devices in the network.
Nodes are connected to the cable by drop lines and taps.
A drop line is a connection running between the device and main cable.
A tap is a connector that attached to the main cable to its mattalic core.
The limited number of taps can be used in bus topology because the signals become weak while treveling through wire and loose their energy in the form of heat.
Advantages:
1. Easy installation by laying the main cable along the effecient path.
2. Less cabling is required.
3. Drop line has to reach to nearest point on main cable.
Disadvantages:
1. Difficult reconfiguration and fault isolation.
2. Difficult to add more devices.
3. A fault or break in connection stops the entire transmission.
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Nodes are connected to the cable by drop lines and taps.
A drop line is a connection running between the device and main cable.
A tap is a connector that attached to the main cable to its mattalic core.
The limited number of taps can be used in bus topology because the signals become weak while treveling through wire and loose their energy in the form of heat.
Advantages:
1. Easy installation by laying the main cable along the effecient path.
2. Less cabling is required.
3. Drop line has to reach to nearest point on main cable.
Disadvantages:
1. Difficult reconfiguration and fault isolation.
2. Difficult to add more devices.
3. A fault or break in connection stops the entire transmission.
Tree Topology
A tree topology is a variation of the star topolgy. As in star topology devices are linked to central hub that control the traffic. However in tree topology the secondry central hubs are again linked to a central hub. In tree topology this central hub is the active hub to control the secondry hubs and traffic.
An active hub contains a repeater (hardware device) that regenrates the bit patterns before sending. It strengthens the transmission and boosted signal travels long distance.
The secondry hubs can be active or passive. The passive hub only provide a simple connection to the central hub and attached devices.
Advantages:
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An active hub contains a repeater (hardware device) that regenrates the bit patterns before sending. It strengthens the transmission and boosted signal travels long distance.
The secondry hubs can be active or passive. The passive hub only provide a simple connection to the central hub and attached devices.
Advantages:
1. This is less expensive.
2. One link and one input/output port is required.
3. Easy installation and reconfiguration.
4. Less cabling is required.
5. If one link fails then other remain active to communicate.
6. Make fault identification and isolation easy.
7. More devices can be attached.
8. It allows the network to isolate and prior the specific computer of a secondary hub to another computer of another secondary hub.
Disadvantages:
1. The only major disadvantage is that if the central hub or controller fails then the entire network goes down.
Star Topology
In a star topology every device in the network has a dedicated point to point link to a central hub. The device not connected to each other in this network. Therefore all traffic flows through the central hub. If one device want to send data to another one then it must be sent to the central controller, which further relays data to other device.
Advantages:
1. This is less expensive.
2. One link and one input/output port is required.
3. Easy installation and reconfiguration.
4. Less cabling is required.
5. If one link fails then other remain active to communicate.
6. Make fault identification and isolation easy.
Disadvantages:
1. The only major disadvantage is that if the central hub or controller fails then the entire network goes down.
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Advantages:
1. This is less expensive.
2. One link and one input/output port is required.
3. Easy installation and reconfiguration.
4. Less cabling is required.
5. If one link fails then other remain active to communicate.
6. Make fault identification and isolation easy.
Disadvantages:
1. The only major disadvantage is that if the central hub or controller fails then the entire network goes down.
Mesh Topology
In a mesh topology every device has a dedicated point to point link to every other device. The term dedicated means that the link carries traffic between the only two connected devices. Therefore in a mesh topology used network has n(n-1)/2 links to n devices. For these links each device must have n-1 input/ouput ports.
Advantages:
1. Traffice errors resolved as each link carries its own data.
2. The disconnection of one link do not disturb the other links and network.
3. The privacy and security remains as only receipent can see the data using a dedicated link.
4. Using the dedicated link to locate the fault and to isolate is much easy.
Disadvantages:
1. The much number of cables and ports in devices are required.
2. Also the installation and reconfiguration is difficult.
3. More space is required for the cabling.
Therefore the mesh topology is apllied to a limited networks or it is used as a backbone in hybrid networks.
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Advantages:
1. Traffice errors resolved as each link carries its own data.
2. The disconnection of one link do not disturb the other links and network.
3. The privacy and security remains as only receipent can see the data using a dedicated link.
4. Using the dedicated link to locate the fault and to isolate is much easy.
Disadvantages:
1. The much number of cables and ports in devices are required.
2. Also the installation and reconfiguration is difficult.
3. More space is required for the cabling.
Therefore the mesh topology is apllied to a limited networks or it is used as a backbone in hybrid networks.
Topology
The term topology refer to the representation of a network laid out either physically or logically.
When two or more devices are connected to a link then two or more links form a topology. It show the links of the entire network with the devcies attached for communication.
There are five basic topologies used for the communicating devices.
1. Mesh Topology
2. Star Topology
3. Tree Topology
4. Bus Topology
5. Ring Topology
There are two possible relationships for connecting the devices.
Peer-to-Peer
In peer to peer devices share the same link equally.
Primary-Secondary
In primary secondry devices one device controls the traffic and the others communicate through it.
Mesh and Ring topologies mostly use the peer to peer transmission. While Tree and Star topologies convenient for primary secondry connections. But Bus topology is equally convenient to both peer to peer and primary secondary.
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When two or more devices are connected to a link then two or more links form a topology. It show the links of the entire network with the devcies attached for communication.
There are five basic topologies used for the communicating devices.
1. Mesh Topology
2. Star Topology
3. Tree Topology
4. Bus Topology
5. Ring Topology
There are two possible relationships for connecting the devices.
Peer-to-Peer
In peer to peer devices share the same link equally.
Primary-Secondary
In primary secondry devices one device controls the traffic and the others communicate through it.
Mesh and Ring topologies mostly use the peer to peer transmission. While Tree and Star topologies convenient for primary secondry connections. But Bus topology is equally convenient to both peer to peer and primary secondary.
