Windows 2008 tcp change

Windows provides a mechanism to control the initial retransmit time, and the retransmit time is then dynamically self-tuned. To change the initial retransmit time, modify the following registry values. Description: This parameter controls the initial retransmission time-out that is used by TCP on each new connection. It applies to the connection request SYN and to the first data segments that is sent on each connection. For example, the value data of " decimal" sets the initial retransmit time to five seconds.

NOTE: You can increase the value only for the initial time-out. Decreasing the value is not supported. Change the following key in Windows NT 4. Description: This parameter controls the initial retransmission time-out used by TCP on each new connection.

It applies to the connection request SYN and to the first data segment s sent on each connection. For prerequisites and more information, click the following article number to view the article in the Microsoft Knowledge Base:. For more information about retransmit time, click the following article numbers to view the articles in the Microsoft Knowledge Base:.

Need more help? Expand your skills. Get new features first. Was this information helpful? Yes No. Thank you! Kind: 3 Length: 3 Option: Window Scale Option Description: Identifies the scaling factor to be used when using window sizes larger than 64k.

For more efficient use of high-bandwidth networks, a larger TCP window size may be used. The TCP window size field controls the flow of data and is limited to 2 bytes, or a window size of 65, bytes.

Since the size field can't be expanded, a scaling factor is used. TCP window scale is an option used to increase the maximum window size from 65, bytes to 1 Gigabyte. The window scale option is used only during the TCP three-way handshake.

The window scale value represents the number of bits to left-shift the bit window size field. The window scale value can be set from 0 no shift to If the window size is 65, bytes with a window scale factor of 3. The window size used in the actual three-way handshake isn't the window size that's scaled, per RFC section 2. It means that the first data packet sent after the three-way handshake is the actual window size.

If there's a scaling factor, the initial window size of 65, bytes is always used. The window size is then multiplied by the scaling factor identified in the three-way handshake. The table below represents the scaling factor boundaries for various window sizes. If the window size in the registry is entered as M in decimal, the scaling factor during the three-way handshake is A scaling factor of 12 only allows a window size up to ,, bytes M. The initial window size in this example would be calculated as follows: 65, bytes with a window scale factor of When the value for window size is added to the registry, and its size is larger than the default value, Windows attempts to use a scale value that accommodates the new window size.

The TcpOpts value in the following registry key can be added to control scaling windows and timestamp:. The valid range is 0, 1, 2 or 3 where: 0 disable RFC options 1 window scale enabled only 2 timestamps enabled only 3 both options enabled.

This registry entry controls RFC timestamps and window scaling options. Timestamps and Window scaling are enabled by default, but can be manipulated with flag bits. Bit 0 controls window scaling. Bit 1 controls timestamps. A timer retransmit timer was set when the packet was sent, until the acknowledgment was received.

For example, if the window size was 64, bytes 44 full segments on an Ethernet network, only one of every 44 packets were used to recalculate the round-trip time. With a maximum window size of 65, bytes, this sampling rate was sufficient. Using window scaling, and a maximum window size of 1 Gigabyte, this RTT sampling rate isn't sufficient. Using this data, the RTT can be accurately calculated with large window sizes. RTT is used to calculate retransmission intervals.

Accurate RTT and retransmission time-outs are needed for optimum throughput. Either side can then use the TCP option during the session. The timestamp option field can be viewed in a Network Monitor trace by expanding the TCP options field, as shown below:.

The TCP sequence number field is limited to 32 bits, which limits the number of sequence numbers available. The Microsoft Press Store by Pearson. As an administrator, you enable networked computers to communicate by using the basic networking protocols built into Windows Server Normally, networking is installed during Windows Server setup.

Domain name The name of the domain in which the computer will be located. This can be a parent or a child domain. Subnet mask The subnet mask for the IPv4 network to which the computer is attached. Subnet prefix length The subnet prefix length for the IPv6 network to which the computer is attached. If you are unsure of any of this information, you should ask the IT staff.

In many cases, even if you are an administrator, there is a specific person you must ask for the IP address setup that should be used. If no one in your organization has this role yet, this role should be assigned to someone or jointly managed to ensure that IP addresses are assigned following a specific plan.