Basic CS-Networks [TCS Placement]: Sample Questions 49 - 49 of 133

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Question 49

Networks
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Describe in Detail

Essay▾

Which layers in OSI are network support layers?

Explanation

Network support layers are:

  • Physical Layer:
    • Responsible for transmission of digital data bits from the physical layer of the sending (source) device over media to the physical layer of the receiving (destination) device.
    • Examples include ethernet cables and token ring networks. Hubs and other repeaters function at the physical layer.
    • Data are transmitted using the signaling supported by the physical medium: electric voltages, radio frequencies, or pulses of infrared or ordinary light.
  • Data Link Layer:
    • Data link layer checks for physical transmission errors and packages bits into data “frames” .
    • Manages physical addressing schemes such as MAC addresses for Ethernet networks, controlling access of any various network devices to the physical medium.
    • Single most complex layer in the OSI model- often divided into two parts, the “Media Access Control” sublayer and the “Logical Link Control” sublayer.
  • Network Layer:
    • Network layer adds routing above the Data Link layer.
    • At the Network layer, the source and destination inside each frame are examined to determine the data has reached its final destination.
      • At final destination, data is formatted into packets and delivered up to the transport layer.
      • Otherwise, destination address is addresses and frame is pushed down to the lower layers.
    • To support routing, the Network layer maintains logical addresses such as IP addresses for devices on the network.
    • Manages the mapping between logical addresses and physical addresses.
    • In IP networking mapping is accomplished through the Address Resolution Protocol (ARP) .

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