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From Andy Wang <aw...@ptc.com>
Subject Re: Speeding up mod_proxy_balancer on Windows
Date Mon, 13 Oct 2008 20:04:46 GMT
Ruediger Pluem wrote:
> Correct and my statement didn't imply to set this registry value to 0. I think
> this is a dangerous road and could lead to other network problems.
>   
While your statement didn't imply that, the microsoft knowledge base
article seems to imply that this registry setting should be used to tune
performance behavior in this scenario.  However, they do warn that
setting it to 0 shouldn't help much.   Apparently, 1s per socket
connection "will make no difference" in their book.  No wonder people
question performance on Windows, especially with the "a second here, a
second there shouldn't matter" mentality.
> I wanted to say that the value Mladen mentioned is not really helping as it
> "normally" should deal with situations where the SYN packets get lost and
> retransmission is due.
> But as we all have to learn again Microsoft has their very own interpretation
> of RFCs:
>
> RFC793:
>
> "Reset Processing
>
>   In all states except SYN-SENT, all reset (RST) segments are validated
>   by checking their SEQ-fields.  A reset is valid if its sequence number
>   is in the window.  In the SYN-SENT state (a RST received in response
>   to an initial SYN), the RST is acceptable if the ACK field
>   acknowledges the SYN.
>
>   The receiver of a RST first validates it, then changes state.  If the
>   receiver was in the LISTEN state, it ignores it.  If the receiver was
>   in SYN-RECEIVED state and had previously been in the LISTEN state,
>   then the receiver returns to the LISTEN state, otherwise the receiver
>   aborts the connection and goes to the CLOSED state.  If the receiver
>   was in any other state, it aborts the connection and advises the user
>   and goes to the CLOSED state."
>
> In particular the last sentence tells us what to do if a SYN is answered
> with a RST:
>
> "If the receiver [of the RST packet] was in any other state, it aborts the
> connection and advises the user and goes to the CLOSED state."
>   
I'm glad you looked that up.   I had found the microsoft kb article
shortly after my last e-mail and didn't bother to question their
statement that the RFC is ambiguous.  After reading that, it's clearly
not ambiguous.  Gotta love what you can do when you're the 800lb gorilla
in the room.


Andy


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