Like most Sys Admins, my job (
in home, just for practice or tweak) includes managing both Linux andWindows machines. This is the start of a two-part series regardingtweaks I have found for networking in each type of system.
First up:Windows.
I have labeled my findings based on where you'll find it: either asan operating system feature, or in the device manager of the Ethernetadapter you're using.
Driver: Interrupt Coalescing / Moderation
Gigabit adapters in particular implement new algorithms to try toaccommodate different forms of network traffic: especially when a goodportion of it may not need that kind of speed (think web-facingadapters on 10/100 lines). However, it has been my own experience thatQuickbooks can be particularly jumpy with this feature enabled. It goesby several different names (depends on the vendor) but you should onlyneed to leave this on if you're using a gigabit interface on anInternet-facing server.
Driver: Offloading (IP / TCP / UDP)
Many adapter drivers come with a form of
offload engine for layer 3 or 4 protocols; there is also a
"Large Segment Offload"feature on some adapters.
These features are meant to reduce CPUoverhead by having the network adapter do more of the work: however, alot of network adapters are sub-par, and there is no harm in having theCPU do these tasks (disabling the offloads) for anything short of aserver-grade adapter. The exception would be
checksum offloading: that seems to be easily doable by any hardware.
2003 & Older: SMB tweaking
Microsoft has offered a set of
registry tweaksthat should improve file sharing performance on older Windows systems:they will have little or no impact on newer systems, for they use
SMB version 2.
XP & Newer: Automatic IPv6 Tunneling
At
GoGoNet Live,I was fortunate to question a Cisco engineer that took credit forhaving Windows implement automatic tunneling with XP and newer: hebelieved that providing IPv6 access, "native" or not, would spurapplication developers to honor API changes and continue to embrace thenew protocol.
Now that 2010 is almost out:
6to4 has been maligned by
Google and
Apple for breaking website access;
ISATAP can be hard to work with;
Teredo tunnelingcan be hit or miss (Microsoft does host some servers for use); and thatdesired application uptake has been largely ignored by the likes of
Pidgin,Steam, and others.
The speaker can be forgiven that his intentions wentawry, when quite a few people (Linux and Windows) think the best way tohandle IPv6 is to
turn it off completely. Fortunately, you don't have to slay the IPv6 beast: its a known fact we'll be living with it
starting in 2011, like it or not.
1. Commands to use on an "administrator" command prompt...
netsh interface ipv6 6to4 set state state=disabled
netsh interface ipv6 isatap set state state=disabled
netsh interface ipv6 set teredo disable
2. On Windows XP systems, you can also disable the "IP Helper" service: however, you'll lose use of the
portproxy function.
3. If you want to use IPv6, and your ISP doesn't have it, consider free (and stable) tunnel services from
HE,
GoGoNet, and
SixXS.
XP x64 & Server 2003: Compound TCP
With the Vista networking stack, a
modified TCP stackwas introduced. I use this "Compound TCP" when I can on the newersystems: fortunately, it has been backported to the 2003-based systemsvia
hotfix 949316.
Vista & Newer: Standard Networking Tweaks
1. I make prudent use of Compound TCP,
TCP timestamping, and
TCP Chimney: the latter is a function of Windows that does partial TCP offloading when able.
At the "administrator" command prompt...
netsh interface tcp set global congestion=ctcp
netsh interface tcp set global time=enabled
netsh interface tcp set global chimney=enabled
2. I prefer not to use
IPv6 privacy addressing for troubleshooting purposes; it can be disabled with the following command...
netsh interface ipv6 set privacy state=disable
3. There is an additional tweak that can help deal with propertraffic routing: however, many routers don't implement it correctly,and Battlefield Heroes doesn't like it at all. Use at your caution.
netsh interface tcp set global ecn=enabled
And there you have ... my list of favorite tweaks.
Thanks...
Monday, May 16, 2011
Anu
