Optimizing Windows XP Network performance using TCP RFC1323 Protocol

In this article, we will learn how to adjust the Windows XP registry parameters through RFC1323. RFC 1323 is a high-performance extension of TCP-to adjust, improve, and optimize network speed and throughput. This technique can help you save the investment required to download software, programs, and even purchase additional network devices or hardware. Windows XP contains several Registry parameters that can dynamically affect performance-one of which is used to process RFC 1323, that is, high-performance TCP extensions. The TCP Window referenced in RFC 1323 is the receiving window, which stores the cache space that reaches the TCP slice, unless (a) packets arrive with the Push tag and are immediately delivered to the application, or (B) receive its application into the cache to retrieve its data. During the TCP handshake, both parties based on the TCP connection will tell the other party their receipt cache size. This is included in the Window Size field of the TCP header. The typical value of this field is 65,535 (it is a 2-byte field, and 65,535 is the maximum value it can represent ). This indicates that, if necessary, the device that sends the handshake packet has 65,535 bytes of space for storing the arrived data. Note: If the TCP Window Scale option is used for initial communication from a TCP node in the TCP handshake packet, Windows Scaling is used by default in the XP system. This means that if your XP device is used as a server (responding to the initial TCP handshake packet), you will use Window Scaling. If your XP device is a client (for example, you connect to an HTTP server or email server), you will not use Window Scaling. If the cache space of a host is exhausted during file transfer, it must send a packet containing the value of Window = 0. The TCP node must stop sending data until a Window Update packet is sent. A window update packet is a simple ACK packet with a non-zero window size value. When the window update process occurs, the data stream may continue. Figure 1 shows that the data stream has stopped because a host declares Window 0 (Window Zero. Figure 1: The receiver host sends a packet with the TCP Window Size field 0 to stop data transmission, because the host has no available cache space and 65,535 of the window size is not enough in current faster links, thicker pipelines, and larger file transfers. Window 0 prompts the creation of Window Scaling, which is defined in RFC 1323. During the TCP handshake, if both parties add the Window Scale option to the TCP packet header, the Window Scale will be supported. Both parties must have such a Window Scale option value so that both parties can use this function. The Window Scale option defines the multiplier used to determine the Window size, as shown in figure 2. Figure 2: The host declares the Window Scale factor of 2 in its TCP handshake packet. This dimension factor increases the size of the actually received Window to 262,140 bytes. The Window size value is a power operation value. For example, if Window Scale is set to 0, the value of the Window Scale field is multiplied by 1 (this will not change the size, it only allows the other party to use the Window Scale ). If the Window Scale value is 1, you should take the Window size field value as 2. For example, if you are downloading an Open Office Suite with a size greater than 75 MB (a suitable size value I usually use to test based on HTTP File Transfer. If you do not activate Window Scaling, but you do want to have a decent throughput ratio, your receiving Window may block the download process because there is only 65,535 of the size of the receiving cache space. Adjust the Window Scaling and set the size factor to 4, which provides a 262,140-byte receiving cache space. To enable the Window Scale setting (and do not enable the timestamp option, I will introduce it in another article), set the value of tcp1323opts to 1. Tcp1323Opts Key: TcpipParameters Value Type: REG_DWORD -- number (flags) Valid Range: 0, 1, 2, 3 0 (disable RFC 1323 options) (disable RFC 1323 option) 1 (window scaling enabled only) (only enable window scaling) 2 (timestamps enabled only) (only enable timestamp) 3 (both options enabled) (enable window scaling and timestamp) default Value: no value. The default behavior is as follows: when initializing a TCP connection, the Timestamp and Window Scale options are not used, however, if the TCP nodes contain them in the SYN film during communication initialization, the timestamp and Window size options are used. Description: This parameter controls the use of RFC 1323 Timestamp and window size TCP options. You can explicitly set the timestamp and window zoom through bits. Bit 0 controls the window size, and bit 1 controls the timestamp. Tip: You must select the baseline for network communication before making any changes. This allows you to verify that your modifications have a positive effect on network communication.