Choose MTU value
On this page you can specify the MTU value, which will be used to optimize your system. If you are unsure about which option to select, it is recommended to follow SySpeed choice. Also pay attention to the messages displayed in the bottom of the page.

 Optimal
SySpeed searches for the packet size which has the optimal round trip time. It takes time up to several minutes, depending on a connection quality.
Usually, it is not recommended to choose this option, because it may give a real profit quite seldom.

 Discovered
This value has been discovered by ping test. Usually, it corresponds to the biggest packet size, which can be transmitted by network media.
NOTE: under poor connection quality discovered MTU could be lower than real MTU used by system, but, at least, there is a guarantee that this MTU can be used with your network media for sure.

 Safe
SySpeed recommends this value as safe. You can trust it in case if there was already several optimizations and SySpeed was able to gather some statistics.
Usually, here is the biggest MTU successfully used in previous optimizations.

 Max Possible
The biggest possible MTU value accordingly specified connection type. SySpeed select it by default if there is no practical information about the network media.
Select this option if you need to achieve the highest network performance. If your network media does not support that big MTU, you will be asked to re-optimize with some smaller MTU.

 System Default
This options means that no exact MTU value will be used. After optimization the system will decide which MTU to use by its own.
NOTE: Some TCP parameters depending on exact MTU value also will be unset (e.g. Receive Window Size).

 Custom
Here it is possible to specify any exact value for the MTU.
NOTE: All MTU values on this page cannot override the biggest MTU value for the previously specified connection type.

Next step: Choose RWIN value or Set other TCP/IP parameters if System Default MTU is selected.

Choose RWIN value
On this page you can specify TCP Receive Window Size (RWIN) value. Move slide bar left or right to set the exact RWIN value.

For the greatest efficiency, the receive window is calculated as a multiple of the TCP maximum segment size (MSS). Currently selected value is displayed below the slider bar in numeric format as well as formula to calculate RWIN with current MSS value.

In general, larger receive windows improve performance over high delay, high bandwidth networks. If RWIN > 64 KBytes is supported, that area is marked with color in the right side of the slider. It is recommended to set RWIN > 64 KBytes only for high bandwidth connection, not for analog modem line.

System default value for receive window depends on operation system.

For Windows 98 or SE it is usually set to 8760 bytes (that is, 8192 rounded up to six 1460-byte segments or MSS * 6).

Under Windows Me, 2000 and XP the window size is normally set to 17,520 bytes (16K rounded up to twelve 1460-byte segments or MSS * 12).

Next step: Set other TCP/IP parameters

Set other TCP/IP parameters

On this page all of TCP/IP parameters, except MTU and RWIN, are enumerated in the list along with their optimal values. Shown valued are not the current values, which are set in the system, but optimal, which will be used to optimize the system.

Every parameter in the list has its own editor. That editor can be used as for changing of the parameter value as for getting more information about it, including explanation about parameter purpose, recommended, default and the most typical values etc.

Example of editor dialog for Time To Live (TTL) TCP/IP parameter. Short explanation about the TTL parameter is displayed in the top of the window. Below controls are presented to select the most typical values for the parameter along with the recommended one. With the custom field any value could be specified.
If default value is chosen, parameter will not be set in the registry, but the shown system default value will be used instead.
In the bottom left corner of the dialog you can see the blue link Default TTL. If clicked it opens the Web page in the Internet containing more information about TTL parameter (true only for Windows 2000 and XP).

To active an editor for any parameter in the list double click on it or select it and then press Ctrl+Enter. In appeared window change the previous value to the new one and store it by pressing OK.

When Next button is pressed, the system is optimized and all TCP/IP parameters are stored in the system registry.