This section describes the following scenarios:
❑10BASE-FL Backbone, 10BASE-FL to-the-Desk
❑10BASE-FL Backbone, Unshielded Twisted Pair to-the-Desk
❑10BASE-FB Backbone, 10BASE-FL to-the-Desk
10BASE-FL Backbone, 10BASE-FL to-the-Desk
When designing an all-10BASE-FL network, keep the following rules in mind:
1.Limit the longest ideal path between any two network stations to 4200 meters due to the IEEE slottime of 51.2 μsec.
2.Limit the length of an 10BASE-FL segment by the optical budget of the link and the overall size of the network. The 802.3 10BASE-FL specification sets 10BASE-FL link distances to 2 km. However, you can generally extend the length if you compute the optical budget and take end-to-end timing into consideration.
3.Each 10BASE-FL Module in a serial path between the two transceivers reduces the maximum cable distance between them by 560 meters
(1836 feet). To be accurate, the equivalent fiber distance is:
❑330 meters for signals that externally enter a 10BASE-FL Module port and go through the backplane
❑230 meters for signals that internally enter a 10BASE-FL Module using the ONline Concentrator backplane
❑560 meters for signals that externally enter and then exit the same 10BASE-FL Module
For simplicity, use 560 meters per 10BASE-FL Module in the path, regardless of the signal's direction, when calculating fiber equivalent distances. Note, however, that this limits the network diameter to less than the maximum size.
