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First a note: The default settings usually work just fine. You can walk
a customer through these changes if the customer is technically savvy,
already has good throughput, and is just looking to improve it a bit.
You can also walk a customer through this if they have been tweaking it
on their own and have made their throughput worse as a result. If the
customer has poor throughput and has never made any registry changes,
then tweaking these settings is usually a waste of time and effort.
Escalate it to Tier II as there is a problem with their line. Please
insure that the cache has been cleared before escalating. Some customers
have cache settings in the hundreds of megabytes, which will slow even a
DSL or Cable modem to a crawl. Set the cache to 10 megabytes and empty
it. Hardcoding an IP and Subnet into the TCP/IP settings of the NIC has
been shown to improve throughput in some cases. The correct IP's and
Subnets are listed on the router pages. If a customer wants or needs to
return to the default settings, just delete these keys and reboot.
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WINDOWS 95/98
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Class\NetTrans\0003
Add a String value and name it: MaxMTU then
set the value to: 1454
or modify it to this.
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP
Add a String value and name it: DefaultRcvWindow then
set the value to: 65535
or modify it to this.
Adding or changing the DefaultTTL values is not necessary and will not
increase the throughput.
If the customer already has one in there, either remove it or set it to
128.
(default TTL for Windows 9x is 64 and NT is 128)
Computer must be rebooted for these changes to take effect
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WINDOWS 98 with ICS enabled, do the above plus:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\ICSharing\Settings\General\
Add a String value and name it: InternetMTU then
set the value to: 1454
or modify it to this.
This key may also be removed completely rather than changing it.
See http://support.microsoft.com/support/kb/articles/q230/1/16.asp
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WINDOWS NT/2000
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters
Add a DWORD value and name it: MaxMTU then
set the value to: 000005AE
or modify it to this. (that's 5 zero's+ and will equal
1454)
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters
Add a DWORD value and name it: TcpWindowSize then
set the value to: 0000ffff
or modify it to this. (that's 4 zero's and 4 F's
and will equal 65535)
Computer must be rebooted for these changes to take effect
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It may be easier and safer to just send the customer here, but remember
to disclaim it and remind them to backup their registry first.
http://www.speedguide.net/files/sguide_tweak_98_pppoe.zip
(for '98 only)
Unzip this .inf file, right-click to install, reboot.
See also: http://www.worldgate.com/~marcs/mtu
http://www.cisco.com/warp/public/105/38.shtml
Note: EnterNet has been modified recently to support lower MRU sizes.
The MTU/MRU sizes are normally negotiated during the connection phase,
and then passed up to the TCP/IP configuration to control the TCP Max
Segment Size (MSS). In the case of Windows, there was no way to update
the TCP protocol dynamically. Starting with version 1.31 for Windows,
and version 1.09b for Mac, the TCP Max Segment Size is now settable at
install time to a default of 1454 for Windows, and 1400 for Mac OS. This
is the optimal setting for these platforms, and should not be modified
by the user. The MTU/MRU negotiation is no longer used for this feature,
so you may see some Configuration Rejects at the protocol level if
you're running traces, but this can be ignored. - Network Telesystems
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