Figure 7-28 Replacing the Network Repeaters with
Switches Reduces the Collision Domains to Two NICs Each
Choosing 1000Base-X Components and Media
Although Table 7-3 shows that there is considerable
flexibility of choice in the 1000Base-X link media, there is not total
flexibility. Some choices are preferred over others:
� NICs
at both ends of the link must be the same 1000Base-X version (CX, LX, or SX),
and the link connectors must match the NIC connectors.
�The
1000Base-CX specification allows either style 1 or style 2 connectors, but style
2 is preferred because some style 1 connectors are not suitable for operation at
1250 Mbps. 1000Base-CX links are intended for patch-cord use within a
communications closet and are limited to 25 meters.
�The
1000Base-LX and 1000Base-SX specifications allow either the small form factor
SFF MT-RJ or the larger duplex SC connectors. Because SFF MT-RJ connectors are
only about half as large as duplex SC connectors, and because space is a
premium, it follows that SFF MT-RJ connectors may become the predominant
connector.
�1000Base-LX
transceivers generally cost more than 1000Base-SX transceivers.
�The
maximum operating range for optical fibers depends on both the transmission
wavelength and the modal bandwidth (MHz.km) rating of the fiber. See Table 7-5.
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