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What are the TCP/IP Limitations with the Networking Components?

	Note that this section discusses how the networking components are implemented on Windows operating systems. For POSIX-compliant operating systems (e.g. Mac OS X, Solaris, etc.), the networking components are implemented using the Berkeley sockets API. Therefore, the limitations of the networking components will vary depending on the type of operating system being used, rather than on POSIX itself.

Customers sometimes ask what limitations exist with the networking components, specifically with regards to the number of sockets that can be created. Any sockets code shipped with Chameleon is based on and has the restrictions of Microsoft WinSock 2.

The TCP/IP limitations are as follows:

Memory Pool

• WinSock allocates sockets in the non-paged memory pool (i.e. memory that cannot be swapped to the page file by the virtual memory subsystem). Once this memory pool is full no more sockets can be created. The pool size is different depending on the operating system you are using and the amount of memory available on the machine. Older Windows operating systems may have more limitations than newer versions. For example, the non-paged memory pool stops growing at 1/8th the size of the memory available on the machine. For Windows NT 4.0, this means a hard maximum of 128 MB; conversely, Windows 2000 has a hard maximum of 256 MB.

• The best way to test this value is to write a small application on the machine you are using to determine how many sockets can be created.

Incoming Connection Stack

• Another limit is imposed on the size of the incoming connection stack. The stack exists in order to cache incoming connections before they are accepted. If the stack is full the next incoming connection is refused. The maximum stack size on Windows NT Workstation, Windows 2000 Professional and Win9x is 5. Windows NT/2000/XP Server's maximum connection backlog size is 200.