HP (Hewlett-Packard) 100BASE-TX ユーザーズマニュアル
Chapter 1
11
Installing and Configuring PCI 10/100 Base-TX
Manual Speed and Duplex Mode Configuration
Manual Speed and Duplex Mode
Configuration
Configuration
Because the PCI 10/100Base-TX/9000 LAN ports support
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 the
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 the
lanadmin -X
command 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.
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.
Since Category 5 UTP contains multiple pairs of wires, it is possible to
have devices on both ends of a link segment sending data to each other
simultaneously. This is known as full-duplex operation. 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.
have devices on both ends of a link segment sending data to each other
simultaneously. This is known as full-duplex operation. 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, and indeed only makes
sense for, switches rather than hubs. It may be found in either 10 Mbit/s
or 100 Mbit/s switch devices. Full-duplex mode may provide a
throughput advantage under some circumstances, but the degree of the
advantage is application-dependent.
sense for, switches rather than hubs. It may be found in either 10 Mbit/s
or 100 Mbit/s switch devices. Full-duplex mode may provide a
throughput advantage under some circumstances, but the degree of the
advantage is application-dependent.
The PCI 10/100Base-TX ports support both half- and full-duplex
operation.
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
Autosensing”.
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
Autosensing”.