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Re: [lwip-users] Understanding retransmission
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From: |
Simon Goldschmidt |
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Subject: |
Re: [lwip-users] Understanding retransmission |
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Date: |
Mon, 19 Jan 2015 16:19:57 +0100 |
Jan Menzel wrote:
> In line 21 the shark records a duplicated ACK, which
> I've seen a few times already (there is one in line 7 for example.).
I don't know what the reason for the Dup ACK in frame #7 is, but for frame #21,
the reason seems to be a corrupted TCP checksum of frame #14.
To see what the reason is here, try to:
- pass TCP_WRITE_FLAG_COPY to tcp_write() (when using the raw api)
- set LWIP_CHECKSUM_ON_COPY to 0 (or LWIP_CHECKSUM_ON_COPY to 1)
and see if that helps (and which of the two).
Also, I've commited a possible bugfix for LWIP_CHECKSUM_ON_COPY some days ago,
maybe that fixes your problem?
Simon