#13634: tcp: rfc-5681: implementing an ideal timer
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Reporter: a-star | Owner: axeld
Type: task | Status: new
Priority: normal | Milestone: Unscheduled
Component: Network & Internet/TCP | Version: R1/Development
Keywords: tcp, gsoc, ideal timer | Blocked By:
Blocking: | Has a Patch: 0
Platform: All |
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Under additional considerations, rfc 5681 discusses the ideal timer:
“After an idle period, TCP cannot use the ACK clock to strobe new segments
into the network, as all the ACKs have drained from the network. In
addition, changing network conditions may have rendered TCP’s notion of
the available end-to-end network capacity between two endpoints. ”
Solution:
“When TCP has not received a segment for more than one retransmission
timeout, cwnd is reduced to the value of the restart window (RW) before
transmission begins. We define RW = min(IW, cwnd)” where IW is the same
described above in the slow start patch.
What I have done:
Whenever new data is received and for the time being we are acting as only
a receiver, we reset the ideal timer.
When we are the sender, and all inflight data gets acknowledged, instead
of cancelling the retransmission timer, we use it as Ideal timer. I have
tried to avoid adding an extra timer since the same work can be
accomplished using the already existing retransmission timer as the cycle
for the ideal timer also equals RTO.
Upon the fire of the retransmission timer, _Retransmit is called. I have
added a condition to check whether the timer was fired due to the ideal
timeout or we actually need to retransmit a segment.
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Ticket URL: <https://dev.haiku-os.org/ticket/13634>
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