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Can someone explain to me why:

netsh interface tcp set global autotuning=disabled

netsh interface tcp set global chimney=disabled

netsh interface tcp set global rss=disabled

is a "magic fix" for so many problems involving network file transfers on Windows 7/2008?

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1 Answer 1

up vote 2 down vote accepted

You're turning off some "new" TCP tuning features (vintage Windows 2003 Scalable Networking Pack and Windows Vista, mostly) that have some problems interoperating with older OS's (and, in some cases, other OS's of the same vintage).

My experience has been that I've needed to disable these features to get reliable operation in only a single circumstance so far, but judging by the amount of ire out there in the community it seems like a lot of people have had to disable them frequently. (I suspect some amount of it is superstition now and these features get disabled "just because" as opposed to being disabled to resolve specific issues.) Some early NDIS 5.1 drivers (NIC drivers) had problems implementing these features correctly and were part of the cause of the early problems,

Here is some background on the features. In general, leaving them enabled (when everything is working on both the client and server) result in the lowest CPU usage and most efficient use of the network (most data in-flight at a time, least round-trips). I've had good luck but, perhaps, I'm just an exception.

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It's odd, because I've had to disable them to resolve problems with network traffic between Windows 7 and Server 2008. –  voltagex Aug 16 '11 at 0:25
    
Furthermore, turning off TCP offloading is a little troubling, because these NICs should definitely support it. –  voltagex Aug 16 '11 at 0:26

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