Tcpwindowsize

The sending host cannot send more data until it receives an acknowledgment and a TCP receive window update. Each TCP packet contains the advertised TCP receive window on the connection. A larger window allows the sender to continue sending data and can improve communication performance.

Supported Clients

This option is valid for all clients.

Options File

Place this option in the dsm.sys file within a server stanza. You can set this option on the Communication tab, Window Size field of the Preferences editor.

Place this option in the client options file (dsm.opt). You can set this option on the Communication tab, Window Size field of the Preferences editor.

Parameters

window_size

Specifies the size, in kilobytes, to use for your client node TCP/IP sliding window. The range of values is 0 through 2048. A value of 0 allows Tivoli® Storage Manager to use the operating system default TCP window size. Values from 1 to 2048 indicate that the window size is in the range of 1KB to 2MB. For Mac OS X, the range of values is 1 through 128. If you specify a value less than 1, the TCP window size defaults to 1. If you specify a value greater than 2048, the TCP window size defaults to 2048.

Note:

1. The TCP window acts as a buffer on the network. It is not related to the tcpbuffsize option, or to the send and receive buffers allocated in client or server memory.
2. A window size larger than the buffer space on the network adapter might degrade throughput due to resending packets that were lost on the adapter.
3. Depending on the operating system communication settings, your system might not accept all values in the range of values.
4. The tcpwindowsize option overrides the operating system's default TCP/IP session send and receive window sizes.

window_size

Specifies the size, in kilobytes, to use for your client node TCP/IP sliding window. The range of values is 0 through 2048. A value of 0 allows Tivoli Storage Manager to use the operating system default TCP window size. Values from 1 to 2048 indicate that the window size is in the range of 1KB to 2MB. The default is 63.If you specify a value less than 1, the TCP window size defaults to 1. If you specify a value greater than 2048, the TCP window size defaults to 2048.

Note:

1. The TCP window acts as a buffer on the network. It is not related to the tcpbuffsize option, or to the send and receive buffers allocated in client or server memory.
2. A window size larger than the buffer space on the network adapter might degrade throughput due to resending packets that were lost on the adapter.
3. Depending on the operating system communication settings, your system might not accept all values in the range of values.
4. The tcpwindowsize option overrides the operating system's default TCP/IP session send and receive window sizes.
5. Windows provides a larger TCP receive window size when communicating with hosts that also provide this support, known as RFC1323. In these environments, a value greater than 63 can be useful.