his approach uses extended-optic gigabit interface converters (GBICs). Although GBIC slots in today's switches were designed for different rea- sons, they still have the potential to be expanded into access points for low- grade MANs. In this scenario, according to proponents, you should deploy fiber rings within cities and connect them to Ethernet switches via their GBIC slots to create high-bandwidth MANs at a low cost using CWDM transceivers and optical multiplexers. In this design, an optical fiber ring is installed in a building with fibers from both the east and west linking with other buildings. Data is transmit- ted at various wavelengths on the ring and can be pulled off or added to the ring at various points or nodes to remove and insert data into the network through an optical add/drop multiplexer (OADM). Data can travel both east and west around the ring to provide two redundant pathways, SO that the network remains viable even if the fiber is broken at one point on the ring. Nodes along the ring can communicate directly with each other via virtual Coarse Wavelength Division Multiplexing (CWDM) Technology EFM FTTH/B Optical Architectures Figure 6-9 Point-to-Point (PtP) Ethernet Mux EFM FTTH/B optical architecture. Ethernet PtP Ethernet over Fiber 1 Gbps and above PtP Ethernet over Fiber 100 Mbps and above up to 20 KM CO/Hub Residence/ Business/MTU point-to-point connections that pass through the intermediary devices. Even though data is flowing around a physical ring, it appears to the nodes that they are linked to each other via two dedicated point-to-point connec- tions. A single wavelength can be dropped to an Ethernet switch connected to CWDM APD GBICs. Services are distributed throughout the building via CAT5 twisted-pair cables. Most Ethernet switches are equipped with 24 or 48 CAT5 unshielded twisted-pair 10/100 Ethernet ports. The GBIC slots inside the switches were originally intended for building the backbone inside a building, but you can also use them to create a backbone through- out a sm