Administering your TCP/IP network

Using ifconfig to change parameters for a network interface

You can use the ifconfig(1Mtcp) command to reconfigure performance parameters for a single network interface. If you wish to make this change permanent you must edit the entry for the interface in /etc/confnet.d/inet/interface (see interface(4tcp)).

The metric, onepacket, and perf parameters affect performance.

metric can be used to artificially raise the routing metric of the interface used by the routing daemon, routed(1Mtcp). This has the effect of making a route using this interface less favorable. For example, to set the metric for the sme0 interface to 10, enter:

/etc/ifconfig sme0 inet metric 10

onepacket enables one-packet at a time operation for interfaces with small buffers that are unable to handle continuous streams of back-to-back packets. This parameter takes two arguments that allow you to define a small packet size, and the number of these that you will permit in the receive window. This deals with TCP/IP implementations that can send more than one packet within the window size for the connection. Set the small packet size and count to zero if you are not interested in detecting small packets. For example, to set one-packet mode with a small packet threshold of one small packet of 512 bytes on the net0 interface, enter:

/etc/ifconfig net0 inet onepacket 512 1

To turn off one-packet mode for this interface, enter:

/etc/ifconfig net0 inet -onepacket

perf allows you to tune performance parameters on a per-interface basis. The arguments to perf specify the default TCP receive and send window sizes in bytes, and whether TCP should restrict the size of a segment to a multiple of 1KB (when set to 0) or use all available space in a frame for a segment (when set to 1).

The following example sets the receive and send window size to 16KB, and uses the maximum space available in an Ethernet frame for each TCP segment:

/etc/ifconfig sme0 inet perf 16384 16384 1


© 1999 The Santa Cruz Operation, Inc. All rights reserved.
UnixWare 7 Release 7.1.1 - 5 November 1999