Basic CS-Networks [TCS Placement]: Sample Questions 38 - 39 of 133

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Question 38


Describe in Detail


What is cladding?


  • A layer of a glass surrounding the center fiber of glass inside a fiber-optic cable is called cladding.
  • This plastic or glass sheath is fused to and surrounds the core of an optical fiber. Inner core of the fiber is the pathway that the light travels through.
  • Cladding՚s mirror-like coating keeps the light waves reflected inside the core.
  • Cladding is covered with a protective outer jacket.
Given the Image is Define the Cladding

Question 39


Describe in Detail


What are the Data link protocols?


  • Data link protocol specifications implement the data link layer.
  • Protocol provides a set of rules to implement layers of the OSI model.

Categories of Data Link Protocols

Asynchronous Protocols

  • ACL provides packet-switched connections between the master and all active slaves.
  • Packet retransmissions are usually applied to assure data integrity.
  • Simple, character oriented protocol՚s generally used on two-point networks using asynchronous data and asynchronous modems.
  • Examples: X-MODEM, Y-MODEM, IBM 83B

Synchronous Protocols

  • The SCO link is point-to-point between master and slave.
  • Master maintains the link by using reserved timeslots at regular intervals.
  • Packets retransmissions are not allowed.
  • Protocols on point to multi-point networks use synchronous data and synchronous modems.
  • Examples: IBM BSC, SDLC, HDLC
  • There are 3 types are character oriented protocol, byte-count-oriented protocol, and bit-oriented protocols.

Character Oriented Protocols

  • Character-oriented protocols use special characters to indicate the beginnings and ends of messages.
  • Best-known character-oriented protocol is the binary synchronous communication protocol also known as BISYNC.
  • BISYNC is defined to only support the 6-bit trans code SBT, EBCDIC and ASCII.
Given the Image is Defining the Character Oriented Protocol Frame Structure

Byte-Count-Oriented Protocols

  • Byte-count-oriented protocols use special characters to mark the beginning of the header, followed by a count field that indicates number of characters in the data portion of the message.
  • The best known byte-count-oriented protocol is the digital data communication message protocol.
Given the Image is Defining the Byte-Count-Oriented Protocol Frame Structure

Bit-Oriented Protocol

  • These do serial bit-by-bit information transfer over the data communications channel
  • Information is transferred as a series of successive bits interpreted individually on a bit-by-bit basis or in groups of several bits as opposed to a fixed length group of bits
  • Example: SDLC, HDLC
Given the Image is Defining the Bit-Oriented Protocol Frame Structure

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