h connect smaller hubs to headend facilities. In addition, CMTSs monitor the level of traffic at each fiber node SO that cable providers are aware when congestion occurs and nodes need to be added to serve fewer homes per node. Moreover, they are responsible for encryption to ensure privacy, secu- rity, and conditional access. Conditional access is the determination of whether a cus- tomer is entitled to certain features. CMTS devices have built-in routers that send traffic to different destinations such as the Internet, long-distance providers, or the cable MSO's VoIP equipment. CMTSs are similar in function to Digital Subscriber Line Access Multiplex- ers (DSLAMs) that are used in traditional telephone company networks in that both devices translate between modems at customers' premises and equipment in back- bone networks. They both also aggregate traffic from multiple subscribers into a single stream for transmission in the backbone. (See the section "Digital Subscriber Line Access Multiplexers," earlier in this chapter, for a discussion on DSLAMs.) Cable Modem Standards to Transition to Higher Speeds Cable standards are intended to provide a technology "road map" for cable MSOs to move toward implementing higher-speed IP networks. The cable industry sets modem standards through CableLabs, the research and development arm of the North and South American cable TV industry. These standards are known as the Data Over Cable System Interface Specifications (DOCSIS). The European Telecommunications Stan- dards Institute (ETSI) and the International Telecommunications Union (ITU) have approved the standards listed in Table 4-3 in the "Appendix" section of this chapter. However, the international versions of DOCSIS vary a little from that used in the United States. Access Networks in Cable Operators' Networks Offering Higher Speeds by Upgrading to DOCSIS 3.0 with Bonding The DOCSIS 3.0 standard specifies support for 38Mbps per 6MHz (6 megahertz) channel. Users on the same node share this capacity. This is why custome