TCS Papers: Sample Questions 400 - 401 of 502

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Question number: 400

» Basic CS » Networks

Essay Question▾

Describe in Detail

What are the responsibilities of Data Link Layer?


The Data Link Layer transforms the physical layer, a raw transmission facility, to a reliable link and is responsible for node-node delivery. It provides following functions:

  • Framing

    • Frames are streams of bits received from the network layer broken into manageable data units.

    • This division of stream of bits is done by Data Link Layer.

  • Physical Addressing

    The Data Link layer adds a header to the frame that defines physical address of the sender or receiver of the frame, if the frames are to be distributed to different systems on the network.

  • Flow Control

    • Provides a flow control mechanism to avoid a fast transmitter from running a slow receiver by buffering the extra bit.

    • Prevents overflow at the receiver side.

  • Error Control

    • Adds a trailer at the end of the frame for error control.

    • Also, duplication of frames is prevented by using this mechanism.

  • Access Control

    Protocols of this layer determine the devices that can control the link at any given time- when two or more devices are connected to the same link.

Question number: 401

» Basic CS » Networks

Essay Question▾

Describe in Detail

What is BGP (Border Gateway Protocol)?


  • Border gateway protocol is an inter-autonomous system routing protocol to advertise reachable networks within an autonomous system.

  • Enables information to be shared with the autonomous system- exchange network reachability information with other BGP systems.

  • Newer than EGP (Exterior Gateway Protocol).

  • Manages packets routed across the internet through the exchange of routing and reachability information between edge routers. Routes packets between autonomous systems (AS) under one service provider.

  • Traffic routed within a single network AS is referred to as internal BGP, or iBGP.

  • BGP connecting one AS to other AS is referred as external BGP, or eBGP.

  • BGP rule is that an AS advertises only those routes that it uses.

  • BGP runs over a reliable transport protocol and uses TCP port for establishing its connections.

The Border gateway protocol (BGP)

The Border Gateway Protocol (BGP)

The Border gateway protocol (BGP)