Be aware of the following two additional rules:
❑Ensure that there are no more than eight 10BASE-FL Modules (and/or 10BASE-T Modules) in the path between any two transceivers due to Ethernet's 4-repeater rule (each 10BASE-FL and 10BASE-T Module counts as a 1/2 repeater). If you have more than eight modules serially connected, you must add a bridge.
❑10BASE-T Modules have an equivalent fiber distance (see Ethernet Rule 4) as follows:
–420 meters for signals that externally enter a 10BASE-T Module port
–165 meters for signals that internally enter a 10BASE-T Module via the ONline Concentrator backplane
For each pair of 10BASE-T Modules that a signal goes through, there is a fiber equivalent distance of 585 meters (420 m + 165 m =585 m). In addition, if a signal makes a roundtrip through a 10BASE-T Module (that is, enters a 10BASE-T port externally and exits through another port on the same 10BASE-T Module), that counts as 585 meters of fiber equivalent distance.
Example: Sample Configuration Distance Calculation
Use the following example to determine if the 10BASE-T Transceivers in Figure 2-7 are within legal Ethernet limits. Identify the two transceivers that are likely to be the greatest fiber equivalent apart in Figure 2-7. In this case, they are 10BASE-T Transceivers A and B.
Designing and Expanding the Network 2 - 21
