ITPEC FE Morning October 2021 Question 32

Flow control — the receiver regulates how much the sender may transmit, so its buffers do not overflow.

At the data link layer the receiver tells the sender when to stop and when to go on, for example with stop-and-wait acknowledgements or a sliding window: the sender may have only a window's worth of unacknowledged frames outstanding, and the receiver's acknowledgements open the window again.

Answer (c)

Why not others:

• •(a) Congestion control — reacts to overload inside the network, mainly at the transport layer (TCP), not to the capacity of one receiver
• •(b) Error control — detects damaged or lost frames (for example with a CRC) and has them retransmitted; it does not pace the sender
• •(d) Media access control — decides which station may use a shared medium and when (for example CSMA/CD), not how much data a receiver will accept

Key rule: Flow control protects the receiver, congestion control protects the network, error control protects the data, and media access control shares the medium.

Networks · AI-written, may contain errors