lwIP - A Lightweight TCP/IP stack - Bugs: bug #24493, Dropped incoming packets cause a...
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bug #24493: Dropped incoming packets cause a burst of duplicate ACKs
Submitter: | Bill Auerbach <billauerbach> | ||
Submitted: | Wed 08 Oct 2008 10:09:48 PM UTC | ||
Category: | TCP | Severity: | 3 - Normal |
Item Group: | Faulty Behaviour | Status: | Invalid |
Privacy: | Public | Assigned to: | None |
Open/Closed: | Closed | Planned Release: | None |
lwIP version: | CVS Head |
Jump to the original submission
Wed 06 May 2009 05:26:47 PM UTC, comment #12: |
Simon Goldschmidt <goldsimon> |
Wed 06 May 2009 02:09:59 PM UTC, comment #11: I'm not duplicating the not recovering problem - you can close it. |
Bill Auerbach <billauerbach> |
Wed 22 Apr 2009 10:35:49 AM UTC, comment #10:
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Simon Goldschmidt <goldsimon> |
Wed 22 Apr 2009 08:06:12 AM UTC, comment #9: I marked this for 1.3.1 because I'd really like to make sure it's at least understood before that release. If there's a situation where connections can completely stall it's a serious bug, but at the moment we're not really sure.
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Kieran Mansley <kieranm> |
Wed 22 Apr 2009 07:20:59 AM UTC, comment #8: Ok, awaiting further investigations, I've changed the planned release to 1.4.0. |
Simon Goldschmidt <goldsimon> |
Tue 21 Apr 2009 09:26:42 PM UTC, comment #7: Simon, I didn't capture at the right times to see the stall because I was after the source of dropped packets, which were real, as they caused us to have real-time issues. The stall happened only a few times over dozens of runs to find the pattern and cause of the dropped packets. Once I figured out how to stop the dropped packets, everything was (and has been) error-free.
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Bill Auerbach <billauerbach> |
Tue 21 Apr 2009 07:22:33 PM UTC, comment #6: Bill, did you have time to capture a transfer where it does not recover?
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Simon Goldschmidt <goldsimon> |
Thu 09 Oct 2008 02:19:12 PM UTC, comment #5: A transfer where it does not recover is indeed interesting. |
Kieran Mansley <kieranm> |
Thu 09 Oct 2008 02:01:58 PM UTC, comment #4: Thank you for the explanation. I understand. We can close this unless you'd like to see a capture where the transfer does not recover. I may have to simulate this so I don't have to wait 9+ minutes for the dropped packets to occur. I believe in my case it's happening because of the burst of data and a single reply packet, which starts yet another burst and so on. It's dropping right after the one packet reply and the next burst. |
Bill Auerbach <billauerbach> |
Thu 09 Oct 2008 01:41:48 PM UTC, comment #3: Perhaps I had relative sequence numbers turned on, and you didn't, which would explain the difference in sequence numbers seen in the trace, sorry.
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Kieran Mansley <kieranm> |
Thu 09 Oct 2008 01:23:00 PM UTC, comment #2: I don't understand - maybe our display options are different? I don't see 8892. I can attach the whole 9+ minute capture if you want me to. Up to what I attached (41000+ packets) all was error-free and after the section with errors it also continued error-free. It's the burst of identical packets that doesn't look right to me. Why is it sending 14 identical packets (except for the identification and checksum) in 100mS without any intervening packet receptions? |
Bill Auerbach <billauerbach> |
Thu 09 Oct 2008 08:17:30 AM UTC, comment #1: From the trace you've shown the behaviour of lwIP looks, at first glace, to be correct.
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Kieran Mansley <kieranm> |
Wed 08 Oct 2008 10:09:48 PM UTC, original submission:
When incoming packets are dropped, lwIP can transmit several duplicate ACKs very quickly in succession. The attached PCAP file shows 14 duplicates ACKs transmitted in 100.1mS. |
Bill Auerbach <billauerbach> |
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Follow 6 latest changes.
Date | Changed by | Updated Field | Previous Value | => | Replaced by |
---|---|---|---|---|---|
2009-05-06 | goldsimon | Status | Need Info | Invalid | |
Open/Closed | Open | Closed | |||
2009-04-22 | goldsimon | Planned Release | 1.3.1 | 1.4.0 | |
2009-04-21 | goldsimon | Status | None | Need Info | |
2009-04-03 | kieranm | Planned Release | 1.3.1 | ||
2008-10-08 | billauerbach | Attached File | - | Added BurstAcks.pcap, #16632 |
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Corresponding source code
I hope it stays like that. Thanks for checking.