Manual Speed And Duplex Mode Configuration - HP -UX 11i Installation And Update Manual

Configuring Built-In PCI Networking
Manual Speed and Duplex Mode Configuration
Manual Speed and Duplex Mode
Configuration
Because this PCI 10/100Base-TX/9000 LAN card supports
autonegotiation, you should not normally need to manually set the
duplex mode. Sometimes you may need to manually set the duplex mode
of the card, for example, if the switch is operating at full-duplex but does
not autonegotiate. Because the card defaults to half-duplex when
autonegotiation is turned off, this could cause a mismatch between the
card and switch (at either 10 or100 Mbits/s). To fix this, use lanadmin -X
as described later in this section.
The CSMA/CD media access method used in IEEE 802.3u-1995 is
inherently a half-duplex mechanism. That is, at any one time, there can
be only one sender of data on the link segment. It is not possible for
devices on either end of the link segment to transmit simultaneously.
Devices on both ends of a link segment can send data to each other
simultaneously (full-duplex mode). While the details of full-duplex
operation are not currently defined by IEEE 802.3u-1995 (full-duplex
mode essentially involves "turning off " the CSMA/CD access method
which is the foundation of IEEE 802.3), the autonegotiation mechanism
defined in IEEE 802.3u-1995 allows devices to advertise and configure
themselves to operate in a full-duplex mode which is essentially
vendor-specific. Devices that do not support autonegotiation can
sometimes be manually configured to operate in full-duplex mode.
Full-duplex mode is most-commonly found in either 10 Mbit/s or 100
Mbit/s switches rather than hubs. Full-duplex mode may provide a
throughput advantage under some circumstances, depending upon the
application. The PCI 10/100Base-TX and 100Base-FX/9000 (V-Class
only) cards support both half- and full-duplex operation.
Ensure that the speed, duplex mode, and autonegotiation of the
associated switch are configured the same as on the PCI 10/100Base-TX
card. If the switch supports autonegotiation on the ports connected to the
cards, this should be enabled as explained in "Autonegotiation and
Auto-sensing" on page 139.
To list the current speed and duplex mode of a PCI 10/100Base-TX/9000
card, use the -x option (lowercase x) in the lanadmin command.
Determine the speed and duplex mode of your hub or switch before
136 Appendix C