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RE: [lwip-devel] Help with TCP stream errors.
From: |
Bill Auerbach |
Subject: |
RE: [lwip-devel] Help with TCP stream errors. |
Date: |
Thu, 30 Apr 2009 17:35:02 -0400 |
>Sounds like the hardware might be generating the wrong checksum. If it
>did this consistently, the connection would never be able to recover, as
>the sequence would go something like this:
Wow, Kieran, I'm impressed. You are in fact correct. Although we had
thoroughly tested the hardware implementation, there was a small race condition
in handling carry-outs and very intermittently we were missing the ending carry
and were off by 1. In a tight loop comparing hardware and software methods
with random data and data sizes and alignment for thousands of passes, it never
failed. Only in the full application sending and receiving data "live" would
it do this.
After you posted this, I tested the 2 methods while running live and did catch
hardware checksums that didn't match the software checksum. I did this check a
lot sooner than I would have had it not been for your help. Thank you!!!
Bill