D-Link DFE-904 User Manual page 8

Standards for 10-Mbps Ethernet and 100-Mbps Fast Ethernet are administered
by the International Institute of Electrical and Electronics Engineers (IEEE). The
DFE-904 conforms fully to IEEE standards for hubs of its type.
As a 10-Mbps Ethernet hub, the DFE-904 conforms to the IEEE's 10BASE-T
standard. 10BASE-T stands for 10-Mbps "baseband" (that is, one-bit-at-a-time)
signaling on twisted-pair cables.
Technical note:
As a 100-Mbps Fast Ethernet hub, the DFE-904 conforms to the 100BASE-TX
Class II standard.
Terminology tip:
100BASE-TX Class II hubs can be connected to each other using twisted-pair
cabling; Class I hubs cannot. A twisted-pair connection between hubs is called
an uplink.
Terminology Tip:
Both 10BASE-T and 100BASE-TX allow uplinking, but the two standards have
very different rules for uplink connections. Follow the connection instructions in
this guide very carefully.
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Twisted-pair cables contain wires wound together in pairs to
reduce electromagnetic interference (EMI). Some also have
foil shielding to further reduce EMI.
The X in 100BASE-TX means that signals cross from the
sender's transmit lines to the receiver's receive lines (this
crossover occurs within the hub). 10BASE-T has crossover
also, but no X; the X was added to distinguish 100BASE-TX
from 100BASE-T4, a Fast Ethernet standard with no
crossover.
In an uplink connection, neither side is really "higher" than
the other; uplinking simply lets each side pass to the other
all valid signals that it receives from networked devices.
Uplinking is sometimes referred to as cascading or daisy-
chaining.