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display for linkage and activity states, and for the speed and duplex settings.
About Fast Ethernet
Fast Ethernet is a network technology specified by IEEE Standard 802.3u. It extends the
traditional 10Mbps (10 megabit/sec) Ethernet technology to achieve 100Mbps (100
megabit/sec) transmission and reception. Because Fast Ethernet retains the traditional
Ethernet CSMA/CD (Carrier Sense, Multiple Access, Collision Detect) protocol, it
remains wholly compatible with 10Mbps Ethernet while providing a tenfold increase in
network capacity.
The Fast Ethernet standard specifies three subtypes, corresponding to three media types:
• 100Base-TX (using two twisted pairs in EIA 568 Category 5 UTP or STP cable)
• 100Base-T4 (using four twisted pairs in a Category 3, Category 4, or Category 5
UTP cable) 100Base-FX (using two fiber-optic strands).
The DFE-680TX provides half-duplex 100Base-TX operation (in Category 5 twisted-pair
cable environments). It does not provide 100Base-T4 or 100Base-FX operation. To
provide for traditional 10Mbps Ethernet operation in twisted-pair cable environments, the
DFE-680TX also offers 10Mbps Ethernet operation, in full-duplex and half-duplex
modes. The DFE-680TX's autonegotiation capability provides for automatic selection of
the best operation mode.
About Autonegotiation
The basic idea of auto- negotiation can be understood by reflecting for a moment on the
familiar process of making a dialup connection between two modems. You have probably
heard some gravelly−sounding exchanges between your local modem and a modem at the
other end of a telephone line. (These exchanges are ordinarily played out through a
speaker in your local modem). As irritating as those few seconds of noise may be, they do
let you know that your modem and the remote modem are on the job, preparing for your
intended communication with the remote computer.
The preparatory work of the two modems during those few seconds before you see the
"connect" message is to negotiate the best data communication scheme which is
supported by both modems, and which is suitable for the quality of the telephone- line
connection between them. The parameters to be settled between the two modems include
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