NoteHKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
| Data type | Range | Default value |
|---|---|---|
| REG_DWORD | 0 | 1 | 2 | 3 | 3 |
Determines whether TCP uses the timestamping and window scaling features described by RFC 1323.
Window scaling permits TCP to negotiate a scaling factor for the TCP receive window size, allowing for a very large TCP receive window of up to 1 GB. The TCP receive window is the amount of data the sending host can send at one time on a connection.
Timestamps help TCP to measuring round trip time (RTT) accurately in order to adjust retransmission timeouts. The Timestamps option provides two four-byte timestamp fields in the TCP header, one to record the time the initial transmission is sent and one to record the time on the remote host.
This entry is a two-bit bitmask. The lower bit determines whether scaling is enabled; the higher bit determines whether timestamps are enabled. To enable a feature, set the bit representing the feature to 1. To disable the feature, set its bit to 0.
| Value | Meaning |
|---|---|
| 0 (00) | Timestamps and window scaling are disabled. |
| 1 (01) | Window scaling is enabled. |
| 2 (10) | Timestamps are enabled. |
| 3 (11) | Timestamps and window scaling are enabled. |
Note
Windows 2000 does not add this entry to the registry. You can add it by editing the registry or by using a program that edits the registry.
Tip
For more information on RFC 1323, see the specification at http://www.cis.ohio-state.edu/htbin/rfc/rfc1323.html.