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3Flow control in data link layer vs flow control in transport layerFlow control in data link layer vs flow control in transport layer

Flow control in data link layer vs flow control in transport layer

Asked 1 years ago
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Before knowing how the layers are actually controlling the flow via various algorithms, you must know the reason why is it actually necessary.

Flow control in transport layer ensures the delivery of the message globally, as the two points of connection over this protocol are logically connected.

Whereas in data-link layer, the concern is to deliver message locally, as the two points of connection over this protocol are physically connected.

Now, coming upon the algorithms that control flow of a network:

  1. Stop and Wait - This flow control mechanism forces the sender after transmitting a data frame to stop and wait until the acknowledgement of the data-frame sent is received.
  2. Sliding Window - In this flow control mechanism, both sender and receiver agree on the number of data-frames after which the acknowledgement should be sent. As we learnt, stop and wait flow control mechanism wastes resources, this protocol tries to make use of underlying resources as much as possible.

These are the 2 basic algorithms for flow control, whereas others are used for error control mechanism.

TCP uses the sliding window protocol for flow control, the size of which is dependent upon the bandwidth, RTT and errors in packets.

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0

Both L2 (Data Link Layer) and L4 (Transport Layer) do flow control.

It's probably well known that TCP (L4) does flow control using sliding window protocol. Together with congestion control, TCP makes great effort to raise transmission efficiency.

There's a physical limit that the medium can transmit at most one frame at any given time, otherwise electrical signals (or other carriers) would interfere with each other, IOW, collides. Therefore, CSMA/CD and analogous come to solve this issue.

You should read those references to get yourself clear.

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0

it has a different approaches in transport layer and data link layer ... because -> transport layer is an end to end communication that is communication between node to node (sender and receiver).. -> where as in data link layer there will be multiple intermediate nodes(routers) present hence flow control mechanism is with respect to adjacent nodes in path between sender and receiver here therefore they have different approaches

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