lwIP - A Lightweight TCP/IP stack - Bugs: bug #27783, Silly window avoidance for small...
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bug #27783: Silly window avoidance for small window sizes
Submitter: | David Empson <dempson> | ||
Submitted: | Thu 22 Oct 2009 09:19:50 PM UTC | ||
Category: | TCP | Severity: | 3 - Normal |
Item Group: | Faulty Behaviour | Status: | Fixed |
Privacy: | Public | Assigned to: | goldsimon |
Open/Closed: | Closed | Planned Release: | None |
lwIP version: | 1.3.1 |
Jump to the original submission
Fri 30 Oct 2009 10:03:10 AM UTC, comment #9: |
Simon Goldschmidt <goldsimon> |
Fri 30 Oct 2009 09:51:32 AM UTC, comment #8: Yes, please change the default TCP_WND to 4MSS. We might want to change the default MSS as well as it is currently very small. 536 bytes is the normal default value for MSS.
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Kieran Mansley <kieranm> |
Fri 30 Oct 2009 09:39:23 AM UTC, comment #7: Hm, but that would make it worse for WND==MSS again. Maybe you're right and sending that many ACKs is OK if the window is that small (since it helps minimize latencies) - which means leave it as it is.
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Simon Goldschmidt <goldsimon> |
Fri 30 Oct 2009 09:04:55 AM UTC, comment #6: Sounds reasonable.
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Kieran Mansley <kieranm> |
Thu 29 Oct 2009 05:22:44 PM UTC, comment #5: I just discovered another problem with our silliy-window-avoidance algorithm: with TCP_WND <= ((TCP_MSS*4)-4) (i.e. window smaller than 4 segments), the algorithm effectively disables the delayed ACK mechanism, i.e. an ACK is sent for every (full-MSS-sized) segment received.
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Simon Goldschmidt <goldsimon> |
Fri 23 Oct 2009 01:18:11 PM UTC, comment #4: Checked in. Thanks for tracking this down with us, David. |
Simon Goldschmidt <goldsimon> |
Fri 23 Oct 2009 08:10:17 AM UTC, comment #3: Looks good, thanks for following this through. |
Kieran Mansley <kieranm> |
Fri 23 Oct 2009 07:12:40 AM UTC, comment #2: Any objections against checking in? |
Simon Goldschmidt <goldsimon> |
Fri 23 Oct 2009 07:12:01 AM UTC, comment #1: As was written in bug #27771, to achieve this, the first if-statement in tcp_update_rcv_ann_wnd() should be changed from
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Simon Goldschmidt <goldsimon> |
Thu 22 Oct 2009 09:19:50 PM UTC, original submission:
Kieran Mansley wrote:
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David Empson <dempson> |
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Follow 4 latest changes.
Date | Changed by | Updated Field | Previous Value | => | Replaced by |
---|---|---|---|---|---|
2009-10-23 | goldsimon | Assigned to | None | goldsimon | |
Open/Closed | Open | Closed | |||
Status | None | Fixed | |||
2009-10-23 | goldsimon | Planned Release | 1.3.2 |
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Corresponding source code
Changed TCP_WND to 4*TCP_MSS and TCP_MSS to 536 in opt.h.