We first apply access control methods to get access to the channel link followed by the flow control methods to stop the receiver from overflowing.

Suppose we are using CSMA/CD in access control method then it has own throughput, efficiency etc. And in flow control we are using suppose Go-back-n(GBN) mechanism then it has also own throughput, efficiency etc.

My question is what is the difference between access control throughput, efficiency and flow control throughput, efficiency?

  • I don't understand the question. throughput is number of successfully transmitted bytes/sec, efficiency is presumably link utilization which is [time spent on something successfully transmitted]/[total time spent] (usually measured over some repeated interval). You can either measure or model said values for method X. Then you get values for method X. If method X is not the same as method Y, then the values would be different. You can measure a real system, having method X, Y, and Z. They you will get value for a combination X, Y, Z. (you can probably model too, but i never saw this done).
    – Effie
    Mar 2, 2022 at 16:13
  • so, i guess throughput and efficiency of access control and flow control are just different values of the same quantities measured for access control and flow control respectively. Since I only saw these values (or models) in isolation, I would assume that the value of access control does not take flow control into account and vice versa.
    – Effie
    Mar 2, 2022 at 16:15
  • @Effie could you answer this question, I waiting for your answer.I need to understand throughout, efficiency of flow control of laye4, layer2(LLC Sublayer of DLL) and access control efficiency, throughput layer2(Mac Sublayer) ?
    – S. M.
    Mar 2, 2022 at 16:24
  • I don't remember how to do it, and I would have to google it as well.
    – Effie
    Mar 2, 2022 at 16:25
  • @Effie could we say access control throughput is less than flow control throughput? please differentiate access control throughput and flow control throughput? Please reply... I am still waiting for your reply.
    – S. M.
    Mar 9, 2022 at 20:06

1 Answer 1


(Ethernet) Flow Control uses pause frames to slow down a sender when it's sending more data than the receiver can handle. It can cause head-of-line blocking and needs to be used with care (or not at all). Flow Control is used for full-duplex transmission only, half duplex used backpressure (deliberate collision/jam signaling).

Access control is a range of protocols that are used to secure access to a physical (switch) port.

CSMA/CD is a largely obsolete media access control (MAC) protocol, used to arbitrate a shared (wired) Ethernet medium.

Go-back-n (ARQ) is an error-control method. Variants are used by the TCP transport-layer protocol and by the wireless IEEE 802.11 data link layer.

All of those are (almost) entirely different things.

  • when we use access control throughput, efficiency means efficiency,throughput of sender Or receiver and flow control (suppose stop and wait)throughput, efficiency means throughput, efficiency of physical link?
    – S. M.
    Mar 1, 2022 at 21:14
  • They have very little to do with each other.
    – Ron Trunk
    Mar 1, 2022 at 21:19
  • @RonTrunk don't understand, please elaborate more.
    – S. M.
    Mar 1, 2022 at 21:21
  • Throughput and efficiency have no meaning for access control.
    – Ron Trunk
    Mar 1, 2022 at 21:23
  • 1
    I think the Wikipedia article explains it better than I can
    – Ron Trunk
    Mar 1, 2022 at 21:37

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