D-Link DES-815, Руководство пользователя

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4 Overview
• The EIA/TIA 568 Wiring Standard does not support the use
of coaxial cables for horizontal wiring.
Network
Network diameter, which is the distance between two end-stations
in the same collision domain, is the primary difference between
traditional Ethernet and Fast Ethernet. Due to the increased
speed in Fast Ethernet and adherence to the EIA/TIA 568 wiring
rules, the network diameter of a Fast Ethernet collision domain is
limited to 205 meters; in contrast, the maximum 10BASE-T
Ethernet collision domain diameter can be up to 2500 meters.
Hubs
Unlike 10BASE-T hubs which are all functionally identical, Fast
Ethernet hubs are divided into two distinct types: Class I and
Class II. A Class I hub repeats all incoming signals on one port to
the other ports by first translating them to digital signals and
then retranslating them back to line signals. These translations
are necessary when connecting various network media to the
same collision domain, such as when combining two wire-pair
100BASE-TX media with four wire-pair 100BASE-T4 media. Only
one Class I hub can exist within the same collision domain, thus
this type of hub cannot be cascaded. A Class II repeater, on the
other hand, immediately repeats all incoming line signals on one
port to the other ports; no translations are performed. This type of
hub connects identical media to the same collision domain; for
example, TX to TX. At most, two Class II hubs can exist within
the same collision domain. The cable used to cascade these hubs is
called an inter-repeater link (IRL).
As mentioned earlier, stackable hubs can be used to increase the
number of available nodes in a collision domain. An entire hub
stack counts as a single repeater.