The TCP(Transmission Control Protocol) delayed duplicate problem is discussed in Tannenbaum's "Computer Networks." The discussion references Tomlinson (1975) improved by Sunshine and Dayal (1978). Basically, from what I could make out it uses a ToD (Time of the day) clock to uniquely number packets and ensure that, if packet lifetime is $T$ secs, then no new packets have the same sequence number within $T$ secs. To elucidate the above fact a graph between sequence numbers and time is drawn which shows the linear relation and marks a Forbidden region, entering which produces duplicate packets.

So here are my questions:

  1. How exactly does entering the forbidden region produces the delayed duplicates?
  2. If I wanted to quantify the discussion with the following parameters:

    a) ToD clock size - 32 bits(keeps running even when the host is down)

    b) clock increases once per milliseconds

    c) maximum packet lifetime - 64 s

How would I find the minimum and maximum permissible sequence number generation rate?


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