Overview of Tuning TCP/IP Parameters

You can set all of the tuning parameters described in this chapter with the ndd command, except for the following two parameters that can only be set in the /etc/system file:

• "tcp_conn_hash_size"

• "ipc_tcp_conn_hash_size"

Use the following syntax to set TCP/IP parameters with the ndd command.

# ndd -set driver parameter

For example, the following ndd command disables IP forwarding.

# ndd -set /dev/ip ip_forwarding 0

See ndd(1M) for more information.

To set a TCP/IP parameter across system reboots, include the appropriate ndd command in a system startup script. Use the following guidelines to create a system startup script to include ndd commands:

• Create a script in the /etc/init.d directory and create links to it in the /etc/rc2.d, /etc/rc1.d, and /etc/rcS.d directories.

• The script should run between the existing S69inet and S72inetsvc scripts.

• Name the script with the S70 or S71 prefix. Scripts with the same prefix are run in some sequential way so it doesn't matter if there is more than one script with the same prefix.

• See the README file in the /etc/init.d directory for more information on naming run control scripts.

See "Run Control Scripts" in System Administration Guide, Volume 1 for more information on creating a startup script.

TCP/IP Parameter Validation

All of the TCP/IP parameters described in this section are checked to verify they fall in the parameter range, which is provided in each tunable section, except for the two parameters that can be set only in the /etc/system file described above. See the validation section for "tcp_conn_hash_size" and "ipc_tcp_conn_hash_size" for more information.

Internet Request for Comments (RFCs)

Internet protocol and standard specifications are described in RFC documents. You can get copies of RFCs by using anonymous ftp to the sri-nic.arpa machine. Browse RFC topics by viewing the rfc-index.txt file at this site.