Hello, everyone!
Today, I continue to write about access network evolution and application – basic concepts and evolution of PON. This is the last article about PON.
P2P/P2MP
P2P (Point-To-Point) or AON (Active Optical Network) topology is the creation of independent links between CO/headend and subscribers. A special fiber stands out for each subscriber - complete bandwidth, security and service isolation. AON (Active Optical Network) has active elements between headend/CO and the user's CPE. There are optical switches and active optoelectronic devices. This solution requires a large number of optical fibers, power supply and high maintenance. This solution is shown in figure 1.
Figure 1. P2P and P2MP topologies
This problem is solved using the P2MP or PON topology. One fiber can be divided into 32 or more subscribers. This significantly saves the capacity of the optical cable. P2MP has only passive optical elements, and no power supply is required and less system maintenance. The reliability of the system increases - there is no RF interference, there are no active elements that require adjustments, maintenance and the overall cost are reduced.
POL
PON can be implemented in LAN. With the introduction of SM optical cables and PON system elements (OLT, optical splitters, ONTs) we get a new solution for LAN. This is called a POL (Passive Optical Local Area Network). This system is totally like the FTTH PON system. POL uses one optical fiber with different wavelengths for transmission downstream and upstream. The maximum distance between OLT and ONT is about 20 km, and the maximum split ratio is 128 (the typical split ratio is about 32 or 64). Figure 2. shows the traditional LAN and POL solution.
Figure 2. Tradicional LAN and new LAN technology - POL
With POL solutions, there are no restrictions as with traditional LAN - cable length, bandwidth, interference, equipment space, equipment power requirements, air conditioning, UPSs, grounding, etc. In addition, fiber optic cables are smaller in diameter and lighter in weight. Consumption is significantly reduced, and a reliable system of great possibilities is obtained. Additional advantages of POL are the introduction of new services - telephony – POTS and television – CATV or IPTV. ONTs can offer 2.4 GHz or 5 GHz WiFi networks.
This is the end of this topic. I will continue to write about this topic in the next article >> Access network evolution and application (5): Data encapsulation of PON system.
Thank you!
