Hardware Reference
In-Depth Information
identified as 10/100 or 10/100/1000 Ethernet. All modern Fast or Gigabit NICs should
also support full-duplex operation:
•Half-duplexmeansthatthenetworkcardcanonlysendoronlyreceivedatainasingle
operation.
• Full-duplex means that the network card can both receive and send simultaneously.
Full-duplex options boost network speed if switches are used in place of hubs. For ex-
ample, 1,000Mbps Gigabit Ethernet cards running in full-duplex mode have a maxim-
um true throughput of 2,000Mbps, with half going in each direction.
Note
Unlike hubs, which broadcast data packets to all computers connected to them, switches cre-
ate a direct connection between the sending and receiving computers. Therefore, switches
provide faster performance than hubs; most switches also support full-duplex operation,
doubling the rated speed of the network when full-duplex network cards are used.
For more information about switches,
see
“
Switches for Ethernet Networks
,”
p.
816
(this chapter).
Bus Type
If you need to install a network adapter for use with a Gigabit Ethernet (10/100/
1000Mbps) network, any of the following buses have more than adequate performance:
• PCI/PCIe. The integrated NIC built in to most motherboards are either PCI or PCIe
devices.
• CardBus/ExpressCard (laptop computers).
All of these buses support Gigabit Ethernet adapters without limiting throughput. Integ-
rated network adapters use either the PCI or PCI Express bus to connect to the system,
both of which have more than enough bandwidth. Note that USB 2.0 (480Mbps) is not on
thatlistbecauseitissimplynotfastenoughtofullysupportGigabitEthernet's1,000Mbps
bandwidth; however, 100Mbps Ethernet connections will work on USB 2.0 with no prob-
lems. USB 3.0 would be more than fast enough to support a Gigabit Ethernet adapter,
however there aren't any network adapters I know of using USB 3.0.
Wired Network Adapter Connectors
WiredEthernetadapterstypicallyhaveaneightposition,eightconductor(8P8C)connect-
or informally known as an RJ-45 connector, which looks like a large telephone jack. Fast
EthernetandGigabitEthernettwisted-paircablesusetheseconnectors,butyoumightstill
see older adapters that support a single BNC connector (for Thinnet coaxial cables) or
