The PCI 10/100Base-TX/3000 product provides the means for interfacing
various types of HP e3000 systems to either a 10Base-T or 100Base-TX
network. 100Base-TX is a subset of 100Base-T networking defined
by the IEEE 802.3u-1995 standard. 100Base-TX provides 100 Mbits/s
data transmission over category 5 unshielded twisted-pair (UTP)
cable for which two pairs of wires in the cable are used — one wire
pair for receiving data, and one wire pair for transmitting data. The
same card port that supports 100Base-TX operation can also support
10Base-T operation (this is true for both the add-on adapter card
and the Core I/O card LAN port).
Autonegotiation is a mechanism defined in the IEEE 802.3u specification
whereby devices sharing a link segment can exchange information
while the link is being established and automatically configure
themselves to operate at the most efficient mode shared between them.
Autonegotiation is like a rotary switch that automatically
switches to the correct technology such as 10Base-T or 100Base-TX
or between half- and full-duplex modes. Once the most efficient
common mode is determined, autonegotiation passes control of the
link to the appropriate technology, sets the appropriate duplex
mode, and then becomes transparent until the link is broken.
The following is the IEEE 802.3u-defined autonegotiation hierarchy
for resolving multiple common abilities for a 10/100Base-TX card:
100Base-TX full-duplex (most efficient)
100Base-TX half-duplex
10Base-T full-duplex
10Base-T half-duplex (least efficient)
For example, if both devices on the link support 10Base-T (half-duplex) and
100Base-TX (half-duplex), autonegotiation at both ends will select 100Base-TX
(half-duplex) instead of 10Base-T (half-duplex).
Many 100Base-TX devices on the market today such as hubs and switches
do not support autonegotiation. Either the speed and duplex mode
of the device are fixed (as is usually the case with hubs), or they are
often manually configured at the desired speed and duplex (as is often
the case for switches). However, switches that support autonegotiation
are becoming more commonplace.
If the PCI 10/100Base-TX/3000 card or the Core I/O card LAN
port is connected to a device, such as a switch, that is autonegotiating,
the PCI card will autonegotiate with the device to mutually determine
the highest possible speed and duplex settings between them.
If the PCI 10/100Base-TX/3000 card or the Core I/O card LAN
port is connected to a device that does not support autonegotiation
or a device that has autonegotiation disabled, the PCI card will
autosense the speed of the link and set itself accordingly. The
duplex mode of the card may be set to half-duplex in this case. If
you want the card to operate in full-duplex mode, you must set it
using the method described in "Notes on Manual Speed and
Duplex Mode Configuration" in this document.
The PCI 10/100Base-TX card or the Core I/O card LAN port will
sense when the connection between itself and a hub or switch on
the other end of a link has been broken. If a connection is made
to another (or the same) device and autonegotiation is enabled,
the autonegotiation and autosensing process will be done again automatically.
Autonegotiation and autosensing are also done whenever the interface
is reset.
Notes on Manual Speed and Duplex Mode Configuration
Complete PDF