What is a TCP keepalive
The main reason to change the your default TCP KEEPALIVE
setting is to allow your platform to close TCP connections that have are
orphaned. An TCP connection may be orphaned for example if a TELNET session is
started on a PC and the user turns off the PC without properly shutting down the
TELNET session.
Your platform will terminate an orphan connection after the
TCP KEEPALIVE period has elapsed. The default for TCP KEEPALIVE, on most
systems, is 2 hours. Until the orphan connection is terminated, it may be
impossible to reestablish a TELNET client
connection
You must be a superuser in order to change TCP KEEPALIVE
parameters. If you can the TCP KEEPALIVE parameters, you must follow the maximum
and minimum settings, listed for you platform. Information on your platform is
listed under Additional Resources.
Changing TCP KEEPALIVE parameters will affect other users
on your platform. TCP KEEPALIVE probes consume bandwidth and can close good
connections if there is a temporary loss of connectivity.
|
KEEPALIVE
Parameters by Operating System |
| Operating System |
Parameter wait time before
probing the connection |
Parameter interval between
probes |
Parameter maximum time or
tries to probe connection before dropping |
Unit of measure |
| Caldera Open Server
5.02-5.06 |
tcp_keepidle |
tcp_keepintvl |
n/a |
half-seconds |
| Caldera Open Unix 8 |
tcp_keepidle |
tcp_keepintvl |
n/a |
half-seconds |
| HP-UX 10.10, 10.20 |
tcp_keepstart |
tcp_keepfreq |
tcp_keepstop |
seconds |
| HP-UX 11.0 |
tcp_time_wait_interval |
tcp_keepalive_interval |
tcp_keepalives_kill |
milliseconds |
| IBM AIX 3,2.5, 4.1.4, 4.2 |
tcp_keepidle |
tcp_keepintvl |
n/a |
half-seconds |
| Digital UNIX 4.0a |
tcp_keepidle |
tcp_keepintvl |
n/a |
ticks (half-seconds) |
| Red Hat Linux 6.2, 6.4, 6.5 |
tcp_keepidle |
tcp_keepintvl |
n/a |
half-seconds |
| Windows 98/ME |
KeepAliveTime |
KeepAliveInterval |
n/a |
milliseconds |
| Windows 2000 NT 4.0 |
KeepAliveTime |
KeepAliveInterval |
TcpMaxDataRetransmission |
milliseconds |
| Windows XP |
KeepAliveTime |
KeepAliveInterval |
TcpMaxDataRetransmission |
milliseconds |
|
Resetting KEEPALIVE by Operating System |
|
Operating System |
Command |
| Caldera OpenServer Open
Unix |
inconfig <tcp_parameter> <nnn_value>
|
| HP-UX 10.10 |
nettune -s <tcp_parameter>
<nnn_value> |
| HP-UX 10.20 |
/usr/contrib/bin/nettune
-s <tcp_parameter> <nnn_value> |
| HP-UX 11.0 |
ndd -set /dev/tcp <tcp_parameter>
<nnnn_value> |
| AIX 3.2.5, 4.1.4, 4.2 |
no -o <tcp_parameter>=<nnn_value> |
| Digital UNIX 4.0a |
dxkerneltuner
Choose inet and click the Select Subsystem button. A panel displays
current values, range of values, and any new settings.
Enter a new setting and choose "Apply." No reboot is necessary. |
| Windows 98/ME |
Run Regedit to edit the
Registry file located in HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\MSTCP
Enter a new value and choose OK.
Reboot after editing. |
| Windows 2000 NT 4.0 |
Run Regedit to edit the
Registry file located in HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters.
Enter a new value and choose OK.
Reboot after editing. |
| Windows XP |
Run Regedit to edit the
Registry file located in HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters.
Enter a new value and choose OK.
Reboot after editing. |
Additional Resources
- Microsoft Windows 95/98/ME
- http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q158474
- Microsoft Windows 2000/NT
- http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q120642
- Microsoft Windows XP
- http://support.microsoft.com/default.aspx?scid=kb;en-us;Q314053
- Other operating systems
- Refer to the system tuning documentation for your respective operating
system. See our documentation list for more information.
|
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