Since GEPON in its classical form has a tree structure, let's start with it.A tree topology implies that a network has a "root", "branches", and "leaves".The "root" in GEPON is the PON port of the OLT, the "leaves" are ONUs, and the "branches" can be considered optical cables laid all the way from the OLT to the ONU.Thus, on the basis of one OLT, it is possible to build four "trees" with a capacity of 64 subscribers each.64 is not a random number, we considered it in a previous article, so in this review it will act as a constant.Figure 1 shows the first type of "tree" (the one that is "lonely growing").There are many variations of this type of topology, but for ease of perception, the simplest case is shown, which is vaguely reminiscent of FTTX.On the provider's side, immediately after the OLT, a 1x8 divider is installed, which is connected to the PON port of the OLT on one side, and to the eight-fiber cable on the other side, which plays the role of the "trunk" of the future "tree".As necessary, the “trunk” is cut, one fiber branches off and boils down from it, from which a “branch” for 8 subscribers begins to grow, and the remaining fibers go further.Each branch from the main trunk is a "subtree" and can be done using a 1x8 divider or a combination of 1x2 and 1x4 dividers.In fact, the network will be N independent "trees" (where N is a multiple of four) in one cable.The multiplicity of four is due to the fact that the OLT has four PON ports, each of which is able to manage a "tree" consisting of 64 subscribers.If the planned connections are 256 or less, then one OLT is installed, and the “multi-tree” is built on a four-fiber cable, but if there are more planned connections, more line terminals are used to manage the network and a more capacious cable.Calculations and practice have shown that the highest efficiency of the bus topology is achieved by combining 1x2 welded dividers and 1x4 and 1x8 planar dividers.To achieve the same stable signal, 5%/95%, 10%/90% and 20%/80% welded dividers must be installed on all ONUs in the cascade.The installation sequence and the obtained values ​​of the signal strength on the ONU can be found at http://local.com.ua in the UA.PON project branch.