ASP State Server
To enable this feature:
Start the ASP.NET state service, either using
the Services snap-in or by executing "net start aspnet_state"
on the command line. The state service will by default listen on port 42424.
To change the port, modify the registry key for the service:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aspnet_state\Parameters\Port
Set the mode attribute of the <sessionState> section to "StateServer".
Configure the stateConnectionString attribute with the values of
the machine on which you started aspnet_state.
<sessionState
mode="[Off|InProc|StateServer|SQLServer|Custom]"
timeout="number of minutes"
cookieName="session identifier cookie name"
cookieless=
"[true|false|AutoDetect|UseCookies|UseUri|UseDeviceProfile]"
regenerateExpiredSessionId="[True|False]"
sqlConnectionString="sql connection string"
sqlCommandTimeout="number of seconds"
allowCustomSqlDatabase="[True|False]"
useHostingIdentity="[True|False]"
stateConnectionString="tcpip=server:port"
stateNetworkTimeout="number of seconds"
customProvider="custom provider name">
<providers>...</providers>
</sessionState>
http://msdn2.microsoft.com/en-us/library/h6bb9cz9(VS.80).aspx
http://samples.gotdotnet.com/quickstart/aspplus/doc/stateoverview.aspx