STUDY NOTES-Networking

Networking

Network is an integrated communication system where different user can exchange data or message.

Computer Network:

Our computer network is inter-connection of different individual computer device using hardware and software resource for the exchanging data or information.

Features of computer network:

1). Line configuration 2. Networking topology 3). Network category 4). Internetworking

5) Transmission media.

Line configuration:

It denotes the types of connection required between the devices for communication. These can be of two fundamental types.

(a) Point- to- point:- These means there is a dedicated line between a particular pair of device.

b)Multi –point: - this means using a common line (BUS). We can connect multiple devices for there inter communication

Network topology:-

Means categorizing network ware to geographical pattern

Mesh denotes direct connection between every individual device it there are n-devices we required N(N-1)/2 connection.

In Bus topology a carrier bus as a communication line connects different devices

In star topology a server acts as a center point to connected different devices.

It in star network every device is connected to left and right neighbour only it forms a ring network.

In tree topology servers are connected to devices using a particular hierarchical manner.

Network category:- Network can be categories according to the area covers by the network. The categories are as follows.

1) Local area network 2) Metropolitan area network 3)Wide area network 4)Global area network.

LAN:- It is a localized network system which comprises of either a small area or a building etc. It consists of a server, which is connected to set of nodes via and electronic device called HUB. Any message or data from server is related the nodes with specific nodes address. The connection is mostly done by using copper cable.

MAN:- different LAN servers in metropolitan city can be inter connected using a master server to create a MAN. These type of network spreads over a city and the connection is done mainly through cables of some times using wireless technology.

WAN:- it is inter city network system to connect different city servers using a master server such network uses connection oriented of connection less technology for connecting different devices and servers. Normally, WAN consist of a single country or a set of country eg. Indian railway reservation system.

GAN:- Inter connecting different WAN creates a globalised network. Which may spread over the globe. Such network mostly uses satellite technology and also connection-oriented technology to perform inter communication. One of the popular examples of such network to Internet.

Transmission Mode:- Transmission mode determines the direction of data flow in case of a communication system.

1) Simplex mode: These systems provides ones specific device to send data and mother specific device to receive data ex. T.V.

2) Half duplex mode:- Here data can flow in both direction but in one specific direction at a time. Ex. Walkie talkie.

3) Full duplex mode:- here data can flow in both direction simultaneously eg. Telephone.

Inter networking:- different network when inter connected either locally or in a wide area, the conception is called internetworking. So, basically network - to – network integration using wireless or wire technology creates Internetwork. Eg. BSNL.

OSI [Open system interconnection]: - ISO has proposed a standard network interfacing software model, for intercommunication between different devices. Such software model is called OSI model. OSI model is a set of specification about standard network software.

1. Application layer 2. presentation layer 3. session layer 4. transport layer 5. network layer 6. data link layer 7. physical layer

In these layer structure lower layer provides basic circuits to its immediate upper layer and the interaction between layers is level by level.

PHYSICAL LAYER: these layer provides specification about physical characteristics like. Voltage to be used, type of signal, how bits will be convert, type of carrier including hardware characteristics are define in these layer.

Data link layer: These layer is responsible for converting signal pattern to its equivalent meaningful binary format to represent data. These includes representation of voltage pattern, specification indicating which voltage represent 1 or which represent o.

(1) Inter-conversion from signal pattern to data form and viceversa.

(2) To check is the send data has been actually received on the receiver side, These layer perform error control activity.

(3) To match the speed of senders transmission with that of receiver. These layer uses flow control mechanism, otherwise there is a possibility of data loss.

NIC: Network interface card

(4) For every machine in a network, there exists two types of address to identify the machine.

(a) physical address denotes a particular electronic circuit or chip no, which is called network interface card, which is a circuit for enabling a machine connected to a network.

(b) When a machine is connected to a server. The server provides local address logical address for a particular node or client.

Such addressing in a network is responsibility of there layer.

Network layer: These layer is responsible for mode-to-node delivery of data packet for transmission of data. The basic function are as follows:

(i) It provides another logical address where data packet is crossing a country or in case of international transmission system.

(ii) These layer to decides cost and time optimized route for transporting data over the network.

Transport layer: These layer responsible for end-to-end delivery of data packet in a network. The basic functions are as follows:

(i) When large amount(vol) of data is required to be transmitted, it is broken up into small parts or pieces, individual piece are transmitted individually. On the receiver side the pieces are to be rearranged to make out original data. These is a vital responsibility of these layer.

(ii) It performs flow control and error control to avoid data loss in case of end-to-end communication.

(iii) For communication of data connection protocol is used before actual communication. The protocol includes connection establishment data transfer and connection termination. All these are perform by transport layer.

Session Layer: These layer performs same basic transmission activity as follows:

(i) It controls process-to-process communication in a network. A process is identified by service access point address(SAP), which is a running programmed.

(ii) It keeps synchronization points for a long data transmission process to keep track of last successful transmission of data packet.

Presentation Layer: These layer performs manipulation of the content of data for over coming different language problem or to introduce data security.

The basic function are as follows:

(i) Different user may use local language, which is must compatible with another user. These layer converts data contents to a global format, transport formatted data over the network, and converts back to local format on the receivers .

(ii) transmitted data may be trapped or used by any unauthorized user which is a problem for data security. Network uses enayption description mechanism to convert data to meaningless form, transmit it over the line and convert back in the receivers end. These mechanism is supported by these layer.

Application Layer: These layer enables human user to access network. It provide a software called network browser, which is used to access a particular network site. Also, the layer provides basic facilities which are as follows:

(i) e-mail: These is a mail delivery service by which user can send or receive mails.

(ii) FTAM: stands for file transfer access management. These is a file handling service to transmit electronic files.

Signal: Signal is a kind of electro- magnetic wave or pattern, which depends on the type of carrier used.

Transmission medium: transmission medium are communication system carriers, which transport signal from sender to receiver device. It can be characterized in two types:

Guided medium: Gm uses physical conducting wires to transmit signals. It is of three types.

(a) Twisted pair wire(b) co-axial cable(c) optical fibre/Fibre optic cable

Twisted pair wire consists of two copper insulated wires would around each other. Twisted pair wire are of two types:

(i) Shielded Twisted pair wire(STP): STP cable has a mesh covering over the twisted pair wires. TP without the outer covering is unshielded.

(j) Unshielded medium: when multiple twisted pair wire are kept transmitted signals can create electric magnetic interreference giving rise to unwanted energy or voltage called cross-talk. These can be avoids by using shielded twisted wire pair.

Co-oxial cable: Co-oxial cable consists of a set of twisted pair wire around a central axis. It is used to carry high values of signal using different frequency. Ex: cable(TV)

Two types:

(1) base band cable: These type of cables carry digital signal will less frequency level.

(2) Broad-band: It carries analog signal with higher frequency.

Fibre-Optic cable: It uses glass medium to transmit signals in the form of light wave. Actually, optical source in used to generate light, the cable is surrounded by rarer glass medium, so that using reflection entire light wave is kept inside the medium and propagated.

Two type:

(1) single mode fibre: uses single light source.

(2) Multi mode fibre: uses multiple light source.

Unguided medium: Uses wireless communication to transmit signals using air medium.

Radio wave communication: These are low frequency signal which can bend when it faces curvature.

Types of RW transmission:

(a) surface propagation: It are low frequency signals travels close to earth surface, the signal can propagate ignoring curvature of the surface.

(b) Tropospheric Propagation: there radio waves are directed toward tropospheric layer and reflected back to the receiving side.

In these case the transmission is line-of-sight type bicog bending is not allow.

(c) Ionospheric propagation: radio waves are transmitted upword, reflected by ionospheric and comes done in and there part of the earth surface.

(d) Space Propagation: These uses satellite communication where gio-stationary satellite are used to reflect back signals down to the earth surface.

Micro-wave communication: Micro-wave is a high frequency electro-magnetic signal which is mostly used in satellite communication.

Geo-stationary satellite are used to accept uploaded signals using uplink frequency and reflect back downloaded signal with downlink frequency.

Transmitter (for uploading) and receiver (for down loading) are faintly available in the form of transceiver medium used by sender or receiver device.

Multiplexing: It is an hardware technique to combine more than one simple signal to form a compo rite carrier signal to be transmitted over network channel.

De-Multiplexing is the reverse process to filter out original simple signal from the comporite carriers on the receiving side.

FDM(Frequnecy Division multiplexing): bandwidth of a network channel: denotes different value in H2 between highest supported frequency range and lowest supported frequency range.

FDM is a technique of combining signal components into one comporite signal, when the channel Bandwidth is higher than the total combine signal bandwidth. So, using signal network channel it is possible to transport set of signal by using a multiplexes hardware.

WDM(wave Division Multiplexing): When optical signal carriers is used to transmit signal as light wave, WDM is used.

These includes combining multiple light signal into one compo rite form using an optical prison, which derives compo rite light wave.

These light wave is transported to receiving side, which de- multiplexes the received signal into individual light waves using another optical prison.

TDM(Time Division Multiplexing):

Synchronous TDM: Here each Host-Machine(sender) is given a fined time-slot, within which the machine can send data over a common network channel TDM multiplexer switches between machine to machine in round robin manner depending on time slot.

Disadvantage:(1) It data transmission is not finish within the time slot for a particular sender, it has to wait before the next chance comes up. It these occurs for many sender will increase system overrate, making system slow.

(2)It sender has nothing to transmit, its time slot is wasted.

Asynchronous Tdm: In asynchronous Tdm. We consider out of n sender not all sender will transmit at the same time. So, no. of time slot is less than n Tdm multiplexer allocate time slot to sender device as per demand.

Advantage: (1) These procedure avoids wastage of time slot and idleness of network channel.

HDLC: (High level data link control): These is a bit oricuted full duplex protocol which is used in a multipoint communication system.

(a) Primary Device- It has right to send data.

(b) Secondary device- it has the right to received data.

(c) Combined device- it is the collection of primary and secondary device.

It is a protocol to present arising errors. It determines where a better msg starts & ends & what part of the msg is included in the CRC. It uses but stuffing for data transferring. Bit stuffing is the method with the help of this are can rectify the ambiguity at data frame if sub string of data matches with the flog bit. Under this mechanism the system will insert a after consecutive five awes. It will malice impossible be find out the flog bit unique.

Project802:IEEE proposed a modification of OSI model by dividing data link layer into two section as action.

(a) Logical link control

(b) Medium access control

These model is called project802 which is mainly used in local area network.

Networking & Internetworking Device:

Networking Device are mostly required in inter-mediate stages in local networking.

Networking Device:

Repeater, Bridge

Internetworking device are mostly required in connecting internal network.

Inter-networking:

Router, gateway

Repeater: It is a connecting device. Which work at physical layer, to regenerate signal strength in case of long distance communication repeater should be install at some distance interval so that original signal can be transported to the receiver. It acts as a regenerate to simplify signal and cut off the noise.

BridgeLConnection of lan)

Bridge is a connecting device which is mainly used to connect Lans. It acts as a repeater when data packet belongs to a neighbouring lan otherwise it can reside destination lan by interacting with other bridges.

Bridge work in data link layer and so it can recognize data link layer address of the transmitted.

Bridge: 1) Simple bridge2) transparent bridge

Simple Bridge: It is a manually operation device where neighboring Lan information are to the entered by an operation Lan logs into network also any division or updation of network device is to the manipulated by an operation.

Transparent Bridge: (It initially has no knowledge about its neighbors when it logs a network by watching different incoming data packet address) it gradually bits it address table.These type of address generation for neighboures is called backwared learning. So in future it will be able to deliver packets to it neighboring Lan.

Router: It is an inter networking device which works in the network layer. Its basic purpose is to route data packets to there destination using network layer address. It uses routing algorithms to decide ideal path so that the packet can reach its destination efficiently. It Router finds the destination address is its neighbours, it simply acts as a bridge.

Router:1) single protocol router2) Multiple protocol router 3) Brouter bridge router.

Single protocol Router: These router can connects distinguish networks which uses similar protocol.

Multiple protocol Router: It can connect different network with variable protocol.

Brouter: It is a combined functionality of a bridge and a Router which is mostly multi protocol Router.

Routing Algorithms: 1) Distance vector Routing: In these algorithm each router maintain a distance vector table which is a table of address for its neighbouring network and routers. All the router are mesh connected so that each router can final several routers to send packet.

The basic activity: 1) Router maintains knowledge about its neighbours.

2) It exchanges information periodically with others which are directly connected.

3) Every router updates its memory table if there is some changes in the network.

4) Link state Routing: In these algorithm every router can share a common data base which stores information abt. Network. The routers are maintaining information about their locality and they also exchange these information with other routers.

The basic activities are:1) The Router keep knowledge about its neighbouring network.

2) Every Router stores its neighbourhood information in UNK state database.

3)Router shares information with other routers only there is change in network.

Routing Process: 1) Adaptive Routing: It means deciding router depending on the present networking condition.

2) Non-Adaptive Routing: It uses fined router which doesnot depends on networking condition.

Gate way: It is an advanced router device which operates in all layers of the OSI interface. It can convert one network protocol to another in case of network to network communication. The basic functions are as follows.

a) It can act as a router.

b) It can convert one network protocol to another.

c) It can send packets to any external network.

d) Network layer protocol:1)ARP 2) RARP 3) ICMP 4)IGMP

ARP: (Address Resolution Protocol) It is a protocol used to find physical address of the host when its internet address is known. In these protocol if a host sends query packet to its server requesting physical address table and response with device address.

RARP: (Reverse ARP) It is a protocol which is used to find internet address of the host when the physical address is known. Here host request it server to send its internet address server find the address and send response.

ICMP: (Internet control Message protocol) It is a protocol used to provides feedback incase of failure in delivery of data packet by any device. In such case the failing device reports back to the predecessor and request for retransmission.

IGMP: (Internet group Message protocol) It is a message bootong protocol where sender can use a) Unicasting- sending message to are receiver.

b) Multicasting: sending message to group of receiver.

c) Broad casting: Sending message to all.

Sonet: (synchronous optical network)It is an example of packet switching optical network which transmits digital data in optical form sonnet uses a special signal called STS which is a high-speed optical signal.

Sonnet device:

1) STS multiplex]

2) STS regenerate

3) STS adol/drop multiplex

STS multiplex: Multiplex takes digital signal uses optical source to generate light wave, converts digital to optical form de-multiplexer perform weres activity.

STS Regenerate: It is use to amplify STS signal for transmission over network.

ADD/Drp mul: These is a foltering device which simple optical signal from a composite.

Sonet layer:1) palk layer- (transport)2) line layer(network)3) section layer(data link)4) photomic layer(physical)

Photomic layer: These is the bottom most layer which provides physical specification about light particle fibre optic channel type of multiplexer used etc.

Line layer: These layer is responsible for resoursing source of destination address and the type of communication channel used.

Palk layer: These layer is responsible transferring digital to optical or digital signal conversion using mux/demux.

Also it is responsible for routing signal user deal router.

X.25:It is an example of packet switching wide area network (WAN) which uses virtual circuite approach tp packet switching.

Physical layer: In these the network uses a protocol called X.21 which consists with specification signal characteristics and grouping of width.

Frame layer: These layer consists construction of frame or packet format using a protocol LAPB (link_Access_Protocol_Balanced) Also, it is responsible for error control and flow control for delivery of data packet.

Frame types: 1) I- frame (Information frame) It carries information about network transport protocol.

5) S- frame(supervisory frame) It carries information about network management.

6) U-frame(Uses frame) It carries information about user data.

Packet layer: These layer is responsible for transporting data packet using a protocol called PLP(packet layer protocol) The protocol uses packet switching with connection establishment virtual circuit creation data transfer connection termination. Each packet contains information about the virtual circuit used.

Q PSK:( Quadrature PSK) IT varies phase change considering for states as O0, Do0 so that use can have four values in the variation of phase.

DISK(Differential PSK) It mixs variation of bit pattern representing phase change in four different states.