Intermodulation noise occurs if two different frequencies are sharing a medium and one of them has excessive strength or the component itself is not functioning properly, then the resultant frequency may not be delivered as expected. Crosstalk This sort of noise happens when a foreign signal enters into the media. This is because signal in one medium affects the signal of second medium. Impulse This noise is introduced because of irregular disturbances such as lightening, electricity, short-circuit, or faulty components.
Digital data is mostly affected by this sort of noise. Transmission Media The media over which the information between two computer systems is sent, called transmission media. Transmission media comes in two forms. In this media, the sender and receiver are directly connected and the information is send guided through it. Unguided Media Wireless or open air space is said to be unguided media, because there is no connectivity between the sender and receiver.
Information is spread over the air, and anyone including the actual recipient may collect the information. Channel Capacity The speed of transmission of information is said to be the channel capacity. We count it as data rate in digital world. It depends on numerous factors such as: Smartzworld. Multiplexing Multiplexing is a technique to mix and send multiple data streams over a single medium.
This technique requires system hardware called multiplexer MUX for multiplexing the streams and sending them on a medium, and de-multiplexer DMUX which takes information from the medium and distributes to different destinations. Networks have interconnecting devices, which receives data from directly connected sources, stores data, analyze it and then forwards to the next interconnecting device closest to the destination.
Switching can be categorized as: Smartzworld. For a computer to use the data, it must be in discrete digital form.
Similar to data, signals can also be in analog and digital form. To transmit data digitally, it needs to be first converted to digital form. Digital-to-Digital Conversion This section explains how to convert digital data into digital signals. It can be done in two ways, line coding and block coding. For all communications, line coding is necessary whereas block coding is optional. Line Coding The process for converting digital data into digital signal is said to be Line Coding.
Digital data is found in binary format. It is represented stored internally as series of 1s and 0s. Digital signal is denoted by discreet signal, which represents digital data. There are three types of line coding schemes available: Smartzworld. In this case, to represent binary 1, high voltage is transmitted and to represent 0, no voltage is transmitted. It is also called Unipolar-Non-return-to-zero, because there is no rest condition i.
Polar Encoding Polar encoding scheme uses multiple voltage levels to represent binary values. Generally, positive voltage represents 1 and negative value represents 0.
It is also NRZ because there is no rest condition. Signals change during bits not between bits. Bit time is divided into two halves. It transits in the middle of the bit and changes phase when a different bit is encountered. It also transits at the middle of the bit but changes phase only when 1 is encountered.
Bipolar Encoding Bipolar encoding uses three voltage levels, positive, negative, and zero. Zero voltage represents binary 0 and bit 1 is represented by altering positive and negative voltages. Block Coding To ensure accuracy of the received data frame, redundant bits are used. For example, in even-parity, one parity bit is added to make the count of 1s in the frame even.
This way the original number of bits is increased. It is called Block Coding. Block coding involves three steps: 1. Division 2. Substitution 3. Analog-to-Digital Conversion Microphones create analog voice and camera creates analog videos, which are treated is analog data.
To transmit this analog data over digital signals, we need analog to digital conversion. Analog data is a continuous stream of data in the wave form whereas digital data is discrete. PCM is one of the most commonly used method to convert analog data into digital form. Sampling The analog signal is sampled every T interval. Most important factor in sampling is the rate at which analog signal is sampled.
According to Nyquist Theorem, the sampling rate must be at least two times of the highest frequency of the signal. Quantization Sampling yields discrete form of continuous analog signal. Every discrete pattern shows the amplitude of the analog signal at that instance. The quantization is done Smartzworld. Quantization is approximation of the instantaneous analog value.
Encoding In encoding, each approximated value is then converted into binary format. Transmission Modes The transmission mode decides how data is transmitted between two computers. The binary data in the form of 1s and 0s can be sent in two different modes: Parallel and Serial. Parallel Transmission The binary bits are organized into groups of fixed length.
Both sender and receiver are connected in parallel with the equal number of data lines. Both computers distinguish between high order and low order data lines. The sender sends all the bits at once on all lines. Because the data lines are equal to the number of bits in a group Smartzworld. Advantage of Parallel transmission is high speed and disadvantage is the cost of wires, as it is equal to the number of bits sent in parallel.
Serial Transmission In serial transmission, bits are sent one after another in a queue manner. Serial transmission requires only one communication channel. Serial transmission can be either asynchronous or synchronous. Asynchronous Serial Transmission It is named so because there is no importance of timing. Data-bits have specific pattern and they help receiver recognize the start and end data bits.
For example, a 0 is prefixed on every data byte and one or more 1s are added at the end. Two continuous data-frames bytes may have a gap between them. Synchronous Serial Transmission Timing in synchronous transmission has importance as there is no mechanism followed to recognize start and end data bits.
Data bits are sent in burst mode without maintaining gap between bytes 8- bits. Single burst of data bits may contain a number of bytes. Therefore, timing becomes very important. It is up to the receiver to recognize and separate bits into bytes. The advantage of synchronous transmission is high speed, and it has no overhead of extra header and footer bits as in asynchronous transmission.
There can be two cases according to data formatting. Bandpass: The filters are used to filter and pass frequencies of interest. A bandpass is a band of frequencies which can pass the filter.
Low-pass: Low-pass is a filter that passes low frequencies signals. When digital data is converted into a bandpass analog signal, it is called digital-to- analog conversion. When low-pass analog signal is converted into bandpass analog signal, it is called analog-to-analog conversion. Digital-to-Analog Conversion When data from one computer is sent to another via some analog carrier, it is first converted into analog signals.
Analog signals are modified to reflect digital data. An analog signal is characterized by its amplitude, frequency, and phase. There are three kinds of digital-to-analog conversions: Amplitude Shift Keying In this conversion technique, the amplitude of analog carrier signal is modified to reflect binary data. When binary data represents digit 1, the amplitude is held; otherwise it is set to 0. Both frequency and phase remain same as in the original carrier signal.
Frequency Shift Keying Smartzworld. This technique uses two frequencies, f1 and f2. One of them, for example f1, is chosen to represent binary digit 1 and the other one is used to represent binary digit 0. Both amplitude and phase of the carrier wave are kept intact. Phase Shift Keying In this conversion scheme, the phase of the original carrier signal is altered to reflect the binary data. When a new binary symbol is encountered, the phase of the signal is altered. Amplitude and frequency of the original carrier signal is kept intact.
Quadrature Phase Shift Keying Smartzworld. This is done in two different phases. The main stream of binary data is divided equally into two sub-streams.
The serial data is converted in to parallel in both sub-streams and then each stream is converted to digital signal using NRZ technique.
Later, both the digital signals are merged together. Analog-to-Analog Conversion Analog signals are modified to represent analog data. This conversion is also known as Analog Modulation. Analog modulation is required when bandpass is used. Analog to analog conversion can be done in three ways: Amplitude Modulation In this modulation, the amplitude of the carrier signal is modified to reflect the analog data.
The amplitude of modulating signal analog data is multiplied by the amplitude of carrier frequency, which then reflects analog data. The frequency and phase of carrier signal remain unchanged. Frequency Modulation In this modulation technique, the frequency of the carrier signal is modified to reflect the change in the voltage levels of the modulating signal analog data.
Phase Modulation In the modulation technique, the phase of carrier signal is modulated in order to reflect the change in voltage amplitude of analog data signal. Frequency of carrier is signal is changed made dense and sparse to reflect voltage change in the amplitude of modulating signal.
Magnetic Media One of the most convenient way to transfer data from one computer to another, even before the birth of networking, was to save it on some storage media and transfer physical from one station to another. For example, a bank has to handle and transfer huge data of its customer, which stores a backup of it at some geographically far-away place for security reasons and to keep it from uncertain calamities.
If the bank needs to store its huge backup data, then its transfer through internet is not feasible. The WAN links may not support such high speed. Even if they do; the cost is too high to afford.
In these cases, data backup is stored onto magnetic tapes or magnetic discs, and then shifted physically at remote places. Twisted Pair Cable A twisted pair cable is made of two plastic insulated copper wires twisted together to form a single media. Out of these two wires, only one carries actual signal and another is used for ground reference. The twists between wires are helpful in reducing noise electro-magnetic interference and crosstalk. This makes it more indifferent to noise and crosstalk.
UTP has seven categories, each suitable for specific use. In computer networks, Cat- 5, Cat-5e, and Cat-6 cables are mostly used. UTP cables are connected by RJ45 connectors.
Coaxial Cable Coaxial cable has two wires of copper. The core wire lies in the center and it is made of solid conductor. The core is enclosed in an insulating sheath. The second wire is wrapped around over the sheath and that too in turn encased by insulator sheath. This all is covered by plastic cover. Because of its structure, the coax cable is capable of carrying high frequency signals than that of twisted pair cable. The wrapped structure provides it a good shield against noise and cross talk.
Coaxial cables provide high bandwidth rates of up to mbps. RG stands for Radio Government. BNC terminator is used to terminate the wire at the far ends.
In PLC, modulated data is sent over the cables. The receiver on the other end de-modulates and interprets the data. Because power lines are widely deployed, PLC can make all powered devices controlled and monitored. PLC works in half-duplex. They can be spread over several kilometers. Broadband PLC provides higher data rates up to s of Mbps and works at higher frequencies 1. They cannot be as much extended as Narrowband PLC. Fiber Optics Fiber Optic works on the properties of light.
When light ray hits at critical angle, it tends to refracts at 90 degree. This property has been used in fiber optic. The core of fiber optic cable is made of high quality glass or plastic.
From one end of it light is emitted, it travels through it and at the other end light detector detects light stream and converts it to electric data. Fiber Optic provides the highest mode of speed. It comes in two modes, one is single mode fiber and second is multimode fiber.
Single mode fiber can carry a single ray of light whereas multimode is capable of carrying multiple beams of light. Fiber Optic also comes in unidirectional and bidirectional capabilities. To connect and access fiber optic special type of connectors are used. Wireless communication involves no physical link established between two or more devices, communicating wirelessly.
Wireless signals are spread over in the air and are received and interpreted by appropriate antennas. When an antenna is attached to electrical circuit of a computer or wireless device, it converts the digital data into wireless signals and spread all over within its frequency range. The receptor on the other end receives these signals and converts them back to digital data.
A little part of electromagnetic spectrum can be used for wireless transmission. Radio Transmission Radio frequency is easier to generate and because of its large wavelength it can penetrate through walls and structures alike.
Radio frequencies are sub-divided into six bands. Radio waves at lower frequencies can travel through walls whereas higher RF can travel in straight line and bounce back. The power of low frequency waves decreases sharply as they cover long distance. High frequency radio waves have more power. They use Ionosphere of earth atmosphere. When they reach Ionosphere, they are refracted back to the earth. Microwave Transmission Electromagnetic waves above MHz tend to travel in a straight line and signals over them can be sent by beaming those waves towards one particular station.
Because Microwaves travels in straight lines, both sender and receiver must be aligned to be strictly in line-of-sight. Microwaves can have wavelength ranging from 1mm — 1meter and frequency ranging from MHz to GHz. As shown in picture above, multiple antennas can be aligned to reach farther. Microwaves have higher frequencies and do not penetrate wall like obstacles. Microwave transmission depends highly upon the weather conditions and the frequency it is using.
Infrared Transmission Infrared wave lies in between visible light spectrum and microwaves. It has wavelength of nm to 1mm and frequency ranges from GHz to THz.
Infrared wave is used for very short range communication purposes such as television and its remote. Infrared travels in a straight line hence it is directional by nature.
Because of high frequency range, Infrared cannot cross wall-like obstacles. Light Transmission Highest most electromagnetic spectrum which can be used for data transmission is light or optical signaling.
Because of frequency light uses, it tends to travel strictly in straight line. Hence the sender and receiver must be in the line-of-sight. Because laser transmission is unidirectional, at both ends of communication the laser and the photo-detector needs to be installed.
Laser beam is generally 1mm wide hence it is a work of precision to align two far receptors each pointing to lasers source. Laser works as Tx transmitter and photo-detectors works as Rx receiver. Additionally, laser beam is distorted by wind, atmosphere temperature, or variation in temperature in the path. Laser is safe for data transmission as it is very difficult to tap 1mm wide laser without interrupting the communication channel.
Multiplexing divides the high capacity medium into low capacity logical medium which is then shared by different streams. Communication is possible over the air radio frequency , using a physical media cable , and light optical fiber.
All mediums are capable of multiplexing. When multiple senders try to send over a single medium, a device called Multiplexer divides the physical channel and allocates one to each. On the other end of communication, a De-multiplexer receives data from a single medium, identifies each, and sends to different receivers.
FDM is an analog technology. FDM divides the spectrum or carrier bandwidth in logical channels and allocates one user to each channel. Each user can use the channel frequency independently and has exclusive access of it.
All channels are divided in such a way that they do not overlap with each other. Channels are separated by guard bands. Guard band is a frequency which is not used by either channel. Time Division Multiplexing TDM is applied primarily on digital signals but can be applied on analog signals as well. In TDM the shared channel is divided among its user by means of time slot. Each user can transmit data within the provided time slot only. Digital signals are divided in frames, equivalent to time slot i.
Both ends, i. Multiplexer and De-multiplexer are timely synchronized, and both switch to next channel simultaneously. When channel A transmits its frame at one end, the De-multiplexer provides media to channel A on the other end. On the other end, the De-multiplexer works in a synchronized manner and provides media to channel B.
Signals from different channels travel the path in interleaved manner. Wavelength Division Multiplexing Light has different wavelength colors. In fiber optic mode, multiple optical carrier signals are multiplexed into an optical fiber by using different wavelengths. This is an analog multiplexing technique and is done conceptually in the same manner as FDM but uses light as signals. Further, on each wavelength time division multiplexing can be incorporated to accommodate more data signals.
FDM divides the frequency in smaller channels but CDM allows its users to full bandwidth and transmit signals all the time using a unique code. CDM uses orthogonal codes to spread signals. Each station is assigned with a unique code, called chip. Signals travel with these codes independently, inside the whole bandwidth. The receiver knows in advance the chip code signal it has to receive. When data comes on a port it is called ingress, and when data leaves a port or goes out it is called egress.
A communication system may include number of switches and nodes. No previous handshaking is required and acknowledgements are optional. Data is then forwarded on that circuit. After the transfer is completed, circuits can be kept for future use or can be turned down immediately. Circuit Switching When two nodes communicate with each other over a dedicated communication path, it is called circuit switching.
There is a need of pre-specified route from which data travels and no other data is permitted. In circuit switching to transfer the data, circuit must be established so that the data transfer can take place. Circuits can be permanent or temporary. Telephone is the best suitable example of circuit switching.
Before a user can make a call, a virtual path between caller and callee is established over the network. Message Switching This technique was somewhere in middle of circuit switching and packet switching.
A switch working on message switching, first receives the whole message and buffers it until there are resources available to transfer it to the next hop. If the next hop is not having enough resource to accommodate large size message, the message is stored and switch waits. As in circuit switching the whole path is blocked for two entities only. Message switching is replaced by packet switching. Packet Switching Shortcomings of message switching gave birth to an idea of packet switching.
The entire message is broken down into smaller chunks called packets. The switching information is added in the header of each packet and transmitted independently. It is easier for intermediate networking devices to store small size packets and they do not take much resources either on carrier path or in the internal memory of switches.
The internet uses packet switching technique. Packet switching enables the user to differentiate data streams based on priorities. Packets are stored and forwarded according to their priority to provide quality of service. This layer is one of the most complicated layers and has complex functionalities and liabilities. Data link layer hides the details of underlying hardware and represents itself to upper layer as the medium to communicate. Data link layer works between two hosts which are directly connected in some sense.
This direct connection could be point to point or broadcast. Systems on broadcast network are said to be on same link. The work of data link layer tends to get more complex when it is dealing with multiple hosts on single collision domain. Data link layer is responsible for converting data stream to signals bit by bit and to send that over the underlying hardware. At the receiving end, Data link layer picks up data from hardware which are in the form of electrical signals, assembles them in a recognizable frame format, and hands over to upper layer.
Functionality of Data-link Layer Data link layer does many tasks on behalf of upper layer. These are: Framing Data-link layer takes packets from Network Layer and encapsulates them into Frames. Then, it sends each frame bit-by-bit on the hardware. At receiver end, data link layer picks up signals from hardware and assembles them into frames.
Addressing Data-link layer provides layer-2 hardware addressing mechanism. Hardware address is assumed to be unique on the link. It is encoded into hardware at the time of manufacturing. Synchronization When data frames are sent on the link, both machines must be synchronized in order to transfer to take place.
Error Control Sometimes signals may have encountered problem in transition and the bits are flipped. These errors are detected and attempted to recover actual data bits. It also provides error reporting mechanism to the sender. Data-link layer ensures flow control that enables both machine to exchange data on same speed. Multi-Access When host on the shared link tries to transfer the data, it has a high probability of collision. The upper layers work on some generalized view of network architecture and are not aware of actual hardware data processing.
Hence, the upper layers expect error-free transmission between the systems. Most of the applications would not function expectedly if they receive erroneous data. Applications such as voice and video may not be that affected and with some errors they may still function well. Data-link layer uses some error control mechanism to ensure that frames data bit streams are transmitted with certain level of accuracy.
But to understand how errors is controlled, it is essential to know what types of errors may occur. Types of Errors There may be three types of errors: Single bit error In a frame, there is only one bit, anywhere though, which is corrupt. Multiple bits error Frame is received with more than one bits in corrupted state. Burst error Smartzworld.
In both cases, few extra bits are sent along with actual data to confirm that bits received at other end are same as they were sent. If the counter-check at receiver end fails, the bits are considered corrupted. Parity Check One extra bit is sent along with the original bits to make number of 1s either even in case of even parity, or odd in case of odd parity.
The sender while creating a frame counts the number of 1s in it. For example, if even parity is used and number of 1s is even then one bit with value 0 is added. This way number of 1s remains even. If the number of 1s is odd, to make it even a bit with value 1 is added. The receiver simply counts the number of 1s in a frame.
If the count of 1s is even and even parity is used, the frame is considered to be not-corrupted and is accepted. If the count of 1s is odd and odd parity is used, the frame is still not corrupted. If a single bit flips in transit, the receiver can detect it by counting the number of 1s. But when more than one bits are erroneous, then it is very hard for the receiver to detect the error.
This technique involves binary division of the data bits being sent. The divisor is generated using polynomials. The sender performs a division operation on the bits being sent and calculates the remainder. Before sending the actual bits, the sender adds the remainder at the end of the actual bits.
Actual data bits plus the remainder is called a codeword. The sender transmits data bits as codewords. If the remainder contains all zeros the data bits are accepted, otherwise it is considered as there is some data corruption occurred in transit.
Error Correction In the digital world, error correction can be done in two ways: Backward Error Correction When the receiver detects an error in the data received, it requests back the sender to retransmit the data unit.
Forward Error Correction When the receiver detects some error in the data received, it executes error- correcting code, which helps it to auto-recover and to correct some kinds of errors. The first one, Backward Error Correction, is simple and can only be efficiently used where retransmitting is not expensive. For example, fiber optics. But in case of wireless transmission retransmitting may cost too much.
In the latter case, Forward Error Correction is used. To correct the error in data frame, the receiver must know exactly which bit in the frame is corrupted. To locate the bit in error, redundant bits are used as parity bits for error detection. For example, we take ASCII words 7 bits data , then there could be 8 kind of information we need: first seven bits to tell us which bit is in error and one more bit to tell that there is no error.
Flow Control When a data frame Layer-2 data is sent from one host to another over a single medium, it is required that the sender and receiver should work at the same speed. That is, sender sends at a speed on which the receiver can process and accept the data.
If sender is sending too fast the receiver may be overloaded, swamped and data may be lost. Two types of mechanisms can be deployed to control the flow: Stop and Wait This flow control mechanism forces the sender after transmitting a data frame to stop and wait until the acknowledgement of the data-frame sent is received. Sliding Window In this flow control mechanism, both sender and receiver agree on the number of data-frames after which the acknowledgement should be sent.
As we learnt, stop and wait flow control mechanism wastes resources, this protocol tries to make use of underlying resources as much as possible. In both cases, the receiver does not receive the correct data-frame and sender does not know anything about any loss. In such case, both sender and receiver are equipped with some protocols which helps them to detect transit errors such as loss of data-frame.
Hence, either the sender retransmits the data-frame or the receiver may request to resend the previous data- frame. If an acknowledgement of a data-frame previously transmitted does not arrive before the timeout, the sender retransmits the frame, thinking that the frame or its acknowledgement is lost in transit. Sender retransmits the frame and starts the timeout counter. When the acknowledgement is received, the sender sits idle and does nothing.
The receiving-window enables the receiver to receive multiple frames and acknowledge them. When the sender sends all the frames in window, it checks up to what sequence number it has received positive acknowledgement. If all frames are positively acknowledged, the sender sends next set of frames. This enforces the sender to retransmit all the frames which are not acknowledged. The sender in this case, sends only packet for which NACK is received.
Network layer manages options pertaining to host and network addressing, managing sub-networks, and internetworking. Network layer takes the responsibility for routing packets from source to destination within or outside a subnet. Two different subnet may have different addressing schemes or non-compatible addressing types. Same with protocols, two different subnet may be operating on different protocols which are not compatible with each other.
Network layer has the responsibility to route the packets from source to destination, mapping different addressing schemes and protocols. Layer-3 Functionalities Devices which work on Network Layer mainly focus on routing. Routing may include various tasks aimed to achieve a single goal. Internet protocol is widely respected and deployed Network Layer protocol which helps to communicate end to end devices over the internet. It comes in two flavors. IPv4 which has ruled the world for decades but now is running out of address space.
Network Addresses are always logical i. Network address is always configured on network interface card and is generally mapped by system with the MAC address hardware address or layer-2 address of the machine for Layer-2 communication. IP addressing provides mechanism to differentiate between hosts and network. Because IP addresses are assigned in hierarchical manner, a host always resides under a specific network. Hosts in different subnet need a mechanism to locate each other. This task can be done by DNS.
DNS is a server which provides Layer-3 address of remote host mapped Smartzworld. When a host acquires the Layer-3 Address IP Address of the remote host, it forwards all its packet to its gateway.
A gateway is a router equipped with all the information which leads to route packets to the destination host. The next router on the path follows the same thing and eventually the data packet reaches its destination.
Multicast traffic uses special treatment as it is most a video stream or audio with highest priority. Anycast is just similar to unicast, except that the packets are delivered to the nearest destination when multiple destinations are available.
This selection process is termed as Routing. Routing is done by special network devices called routers or it can be done by means of software processes. The software based routers have limited functionality and limited scope. A router is always configured with some default route.
A default route tells the router where to forward a packet if there is no route found for specific destination. One route can be configured to be preferred over others. Unicast routing Most of the traffic on the internet and intranets known as unicast data or unicast traffic is sent with specified destination.
Routing unicast data over the internet is called unicast routing. It is the simplest form of routing because the destination is already known.
Hence the router just has to look up the routing table and forward the packet to next hop. Routers create broadcast domains. But it can be configured to forward broadcasts in some special cases. A broadcast message is destined to all network devices. In this case, the router creates multiple copies of single data packet with different destination addresses.
All packets are sent as unicast but because they are sent to all, it simulates as if router is broadcasting. All routers are configured in the same way. This technique is used to detect and discard duplicates. In broadcast routing, packets are sent to all nodes even if they do not want it.
But in Multicast routing, the data is sent to only nodes which wants to receive the packets. The router must know that there are nodes, which wish to receive multicast packets or stream then only it should forward.
Multicast routing works spanning tree protocol to avoid looping. Multicast routing also uses reverse path Forwarding technique, to detect and discard duplicates and loops. Anycast Routing Anycast packet forwarding is a mechanism where multiple hosts can have same logical address. When a packet destined to this logical address is received, it is sent to the host which is nearest in routing topology.
Whenever an Anycast packet is received it is enquired with DNS to where to send it. Unicast Routing Protocols There are two kinds of routing protocols available to route unicast packets: Distance Vector Routing Protocol Distance Vector is simple routing protocol which takes routing decision on the number of hops between source and destination. A route with less number of hops is considered as the best route. Every router advertises its set best routes to other routers.
Ultimately, all routers build up their network topology based on the advertisements of their peer routers, for example, Routing Information Protocol RIP. It takes into account the states of links of all the routers in a network. This technique helps routes build a common graph of the entire network. Multicast Routing Protocols Unicast routing protocols use graphs while Multicast routing protocols use trees, i.
The optimal tree is called shortest path spanning tree. It is used in dense environment such as LAN. It is used in sparse environment such as WAN. Routing Algorithms The routing algorithms are as follows: Flooding Flooding is simplest method packet forwarding. When a packet is received, the routers send it to all the interfaces except the one on which it was received.
This creates too much burden on the network and lots of duplicate packets wandering in the network. Time to Live TTL can be used to avoid infinite looping of packets. There exists another approach for flooding, which is called Selective Flooding to reduce the overhead on the network.
In this method, the router does not flood out on all the interfaces, but selective ones. Shortest Path Routing decision in networks, are mostly taken on the basis of cost between source and destination. Hop count plays major role here. Shortest path is a technique which uses various algorithms to decide a path with minimum number of hops.
There may exist requirement of connecting two different networks of same kind as well as of different kinds. Routing between two networks is called internetworking. Networks can be considered different based on various parameters such as, Protocol, topology, Layer-2 network and addressing scheme.
They can be statically configured go on different network or they can learn by using internetworking routing protocol. Routing protocols which are used within an organization or administration are called Interior Gateway Protocols or IGP. Routing between different organizations or administrations may have Exterior Gateway Protocol, and there is only one EGP i.
Border Gateway Protocol. Tunneling If they are two geographically separate networks, which want to communicate with each other, they may deploy a dedicated line between or they have to pass their data through intermediate networks. Tunneling is a mechanism by which two or more same networks communicate with each other, by passing intermediate networking complexities. Tunneling is configured at both ends.
This tagged data is then routed inside the intermediate or transit network to reach the other end of Tunnel. When data exists the Tunnel its tag is removed and delivered to the other part of the network.
Both ends seem as if they are directly connected and tagging makes data travel through transit network without any modifications. Some of the data communication and networking questions and answers are mentioned below.
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