Chapter 3: Installation Requirements and Specifications
3.2NETWORK 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 ∝s.
A stack of five SEH hubs or four SEH hubs and one SEHI hub is equivalent to one repeater.
A 100BASE-T network might use all UTP links, all fiber links, or a combination of both. 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 optic, 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 multimode fiber optic, the maximum length is 274 meters.
If a buffered uplink (EPIM-100FMB) is used, the collision domain is stopped at the EPIM slot. This allows a full length fiber optic link of 400 meters to be used as an uplink while maintaining 100-meter UTP and 400-meter fiber optic lengths to desktops. So if segment A, shown in Figure 3-1, is UTP and segment B is fiber optic, the maximum length of the network is 500 meters. If both segments are fiber optic, the maximum length is 800 meters.
SEH100TX-22
Figure 3-1 Class I Network
