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Chapter 3: Installation Requirements and Specifications
3-4 SEHI100TX User’s Guide
3.2 NETWORK CABLE LENGTHS
This section details the maximum network cable lengths specified by the
IEEE 802.3u standard for a Class I repeater. As stated previously, the
physical size of the network is limited primarily by propagation delay.
The round trip delay cannot exceed 512 bit times or 5.12 µs.
A 100BASE-T network might use all UTP links, all fiber links or a
combination of both. Table 3-1 details the maximum link lengths for each
type and combination of cable when used with a Class I repeater.
Figure 3-1 shows a simplified example of a network with one Class I
repeater. Link segments A and B represent the longest links in the
network. In this case, if both segment A and segment B are UTP, each
segment may be up to 100 meters long for a maximum network length of
200 meters. If segment A is UTP and segment B is fiber, the maximum
length of the network is 263 meters (with a maximum UTP segment
length of 100 meters). If both segments A and B are fiber, the maximum
length is 274 meters.
NOTE
A stack of five SEH hubs or four SEH hubs and one SEHI hub
is equivalent to one repeater.
!
CAUTION
The maximum length of an individual UTP segment may be no
more than 100 meters.
Table 3-1 Maximum Class I Network Cable Length
Number of
Repeaters
UTP UTP & Fiber Fiber
1 200 m 263 m 274 m
SEHI Book Page 4 Wednesday, May 15, 1996 10:42 AM