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Baseband LAN :- ALAN that uses a single carrier frequency over a single channel. Ethernet . Token Ring use baseband TX .

Broadband N.W:- a N.W that uses multiple carrier frequencies to TX . multiplexed signals on a single cable without interfering with one another .


Ethernet :- A LAN Technology . is a 10 Mbps CSMA/CD baseband N.W . that runs thin , thick coax and twisted pair or fiber optic cable .

Communication Server :- A dedicated standalone System that manages communication activities for other computer.


File Server :- A computer that stores data for N.W users on Disks ,CD’s , Mag Tapes , and provides N.W .access to that data.

CSMA/CD :- carrier sense Multiple Access with collision detection is the Ethernet media access method . all N.W . devices request equally for access to TX . if a device detects another device’s signal while it is TX . if a device detects another device’s signal while it is TX . it stops TX and try again after a brief pause .


Internet :- a series of interconnected local . regional , National , and international N.W’S , linked using TCP/IP.

TCP/IP :- Transmission control protocol (TCP) and internet protocol (IP) are the stander N.W protocols in UNIX environments.


Protocol :- A procedure to intiate and maintaine communication in a N.W .

LAN:- A data communication system consisting of a group of interconnected computer’s . sharing application , data and peripherals . less (1KM)in diameter.


WAN:- A N.W .using communication carrier TX . services for TX of data over more than (1KM) in diameter .
ISO Layered Model :- the international standards organization (ISO) set standards for computer’s and communication .it’s open system interconnection (OSI) reference model specifies how dissimilar computing devices such as NW. interface card (N.I.C)and routers exchange data over a N.W .

Layer:- In N.W’S layers refer to S.W protocol levels comprising the architecture , with each layer performing functions from the layer above it .


NIC :- An adapter card that is inserted into a computer and contain the necessary S.W .and H.W. to enable the station to communication over the N.W .

OSI :- A seven layer model developed by ISO that governs communication interchange between systems .


Repeater : - A N.W device that repeaters signals from one cable onto one or more other cables , while restoring signal timing and wave forms.

Ring :- N.W topology in which the nodes are connected in a closed loop data is TX from node to node around the loop, always in the same direction .


Packet :- A series of bits containing data and control information including source and destination node addresses formatted for TX from one node to another .

Store and Forward :- Technique for examing incoming packets on an Ethernet Switch or bridge whereby the whole packet is read before forwarding or filtering takes place . store and forward is a slightly slower process than cut-through , but it does insure that all bad or misaligned packet are eliminated from the N.W by the switching device.


Cut through :- Another technique for examing packet in an Ethernet ,here the switch looks only at the first few bytes of a packet before forwarding or filtering it . this process is faster than looking at the whole packet , but it also allows some bad packet to be forwarded .

B and D channels :- these are channels used to handle voice ( B channel) and data (D channel ).


Client /Server :- A client initiates communication, while a server waiting to be contacted by the communicating client .

Congestion :- A state in which a N.W is over loaded with packets . if it is not handled by protocol S/W the N.W will suffer from congestion collapse .

Connection oriented N.W :- here the TX and RX must establish a connection before sending data .


Connectionless oriented N.W :- here the TX protocol carry enough information to reach RX without the N.W monitoring the transfer .

Datagram :- A packet may be transmitted where there is no guaranteed sequential delivery .


Route :- Is a computer that connects two or more N.W’s and forward packets according to information found in its routing table .

User Datagram protocol (UDP) :- the TCP/IP protocol that provides application programs with connectionless service .


Protocol Data Unit (PDU) :- the unit of information transferred between communicating peer layer processes .



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