Re: TCPv4 errors?
William Sowerbutts (btg@thepentagon.com)
Mon, 30 Dec 1996 23:53:31 +0000
At 12:29 30/12/96 -0700, Mike Wangsmo wrote:
>On Mon, 30 Dec 1996, Richard B. Johnson wrote:
>
><<STUFF SNIPPED>>
>
>> Given this, I suspect that the error messages are ___PREFECTLY_NORMAL___,
>> considering the junk that we are forced to purchase. The best Ethernet
>> card I have found was a 3COM 3C509. It isn't very fast but at least the
>> interface timing is correct. Some of the alleged 100 mb/s cards, i.e.,
>> more modern boards are terrible.
>>
>> But... If one out of every 100 packets is errored due to poor interface
>> timing, that's 99% efficiency. If the board is a few percent faster, in
>> spite of its errors, the result might be a performance gain. This presumes
>> that the packet that has to be retransmitted comes from a compliant
>> IP interface that correctly keeps track of the packets. Some don't, so
>> you get a whole bunch of duplicates that have to be ACKed and thrown away.
>
>I don't have any ethernet cards installed in my box. These errors are
>from my ppp stuff and have only just recently started happening, ie after
>2.1.15.
>
>Mike
Sounds to me like it's probably corruption in the data coming from the
modem then. Have you got a 16550 UART? If not, your UART could be dropping
characters. If your modem doesn't support error correction (unlikely) or
you have a super-duper noisy phone line, that could also corrupt the IP
packets as they are transmitted to you. Maybe the reporting of this error
was introduced only recently, and that's why you've not seen this error
before.
_________________________________________________________________________
William R Sowerbutts (BtG) btg@thepentagon.com
Coder / Guru / Nrrrd http://www.users.dircon.co.uk/~guru/
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(m=-1;m<7;putchar(m++/6&c%3/2?10:s[c]-31&1<<m?42:32));}