ork congestion and delays, if capacity is insufficient between the DSLAM and the central office. When telecoms move fiber closer to customers in neighborhoods, they often use mini Remote Access Multiplexers (mini-RAMs), which are about the size of pizza boxes, to convert light signals carried on fiber to electrical signals and vice versa. Installing fiber closer to homes results in shorter copper lengths. Shorter copper runs have fewer impairments because electrical signals fade less as they travel over shorter distances. Impairments found on longer copper runs farther from central offices cause DSL speeds to decrease dramatically and often prevent DSL from being viable at even slower speeds. Traffic from mini-RAMs is aggregated in DSLAMs, from where it is transmitted over fiber to central offices and the Internet. Mini-RAMs can be located on utility poles or in stand- alone boxes on the ground and serve 10 to 24 customers (see Figure 4-9). Local power is not required because it is fed to mini-RAMs through the copper telephone lines either on the pole or underground. www.TechnicalPDF.com DSLAM Mini-RAM aggregation switch Copper-to-DSL modems in homes Headend Central office Mini-RAM Fiber Internet DSLAM Figure 4-9 Mini Remote Access Multiplexers (mini- RAMs), located in neighborhoods, deliver cable TV and high-speed Internet access. The Case for Fiber to the Home-More Capacity and Less Maintenance Cable TV providers and telephone companies in the United States and other countries sell "triple play" services: voice, TV and movies, and Internet access to enterprises, hotels, restaurants, and municipalities as well as residential customers. One way they provide capacity needed to handle all of these services is to add fiber closer to homes and businesses or directly to premises. When carriers transition to fiber to homes, voice signals are sent in digital, voice over Internet (VoIP) packets, rather than as electrical signals on copper cabling. Providers that transition to fiber to homes or even fiber close to homes i