Issue link: http://www.epageflip.net/i/1043933
14 I ICT TODAY • Extremely reduced cable management. • Possible flexibility for MACs, depending on the design. • Immunity to EMI, like other fiber-based solutions. However, this technology was not originally designed for the LAN environment, so it also has drawbacks: • Expensive network equipment, designed for sending signals for long distance. • Lack of choice in the network equipment, as there are very few suppliers. • Need for "electronic boxes" at the user level, called optical network terminals (ONTs). These must often be on desks, subject to risks, although newer models can now integrate into the walls, ceiling or furniture. • Dependence on local power supply, and with difficulty to create redundancy. • Low performance: one fiber port with 10G performance from the core switch can be divided into 32 strands each connected to a 4-port ONT, effectively providing an average of 78 Mb/s per port. For comparison, a 48-port gigabit switch connected on Cat 5e with a 10G backbone on OM3 provides more than 200 Mb/s on average. PON technology provides a low-cost solution, immunity to EMI, while saving space and equipment in the FDs. It also allows longer distances than all other op- tions. But it is not without drawbacks, limiting it also to niche applications. In fact, PON technology is very simi- lar to FTTO, with less fiber cabling and longer distances, but with lower performance and equipment specific to a wireless area network (WAN) rather than a LAN environment. Patching Complicated Simple Simple Extra simple Cabling quantities and pathway sizes High Low Extra low Lowest Ease of MACs Difficult 1 Easy Difficult 1 Difficult 2 Data rate available to the user with typical installation High High Low Lowest Compatible 10Gb/s to the user with technology Yes Yes No No Compatible 40Gb/s to the user with current technology No 3 Yes No No Implementation of power redundancy Simple Simple Complex Complex Efficiency of PoE distribution Inefficient Efficient Efficient (from mini-switch) Efficient (from ONT) Choice of compliant active equipment Wide choice Wide choice Low choice Low choice Traditional Star FTTZ FTTO PON 1 Unless using CPs or MUTOAs 2 Unless splitters are placed strategically and have unused ports 3 On most links, due to distance TABLE 1: Key attributes of the various designs.