s Connection) A proprietary optical networking system. ESP (Encapsulated Security Payload) A security system in which IP datagram data is encrypted. ESS (electronic switching system) A system that uses computer-like operations to switch telephone calls. Ethernet A baseband LAN specification that operates at 10/100/1,000Mbps by using CSMA/CD running over thick or thin coaxial, twisted-pair, or fiber-optic cable. Standards have been devel- oped for Gigabit Ethernet and 10Gbps Ethernet, and they are being developed for 100Gbps Ethernet as well. Ethernet is defined in IEEE 802.3. ETRI (Electronics and Telecommunications Research Institute) A nonprofit Korean government-funded research organization that has been at the forefront of technological excel- lence for more than 25 years. ETSI (European Telecommunication Standards Institute) A telecommunications standardization organization. Euro-DOCSIS The European version of the U.S. DOCSIS standard. The goal of Euro-DOCSIS is to ensure correct and optimal performance of Euro-DOCSIS modems and CMTSs in European networks as well as being fully compliant with the European DVB standard in the downstream. even parity check A test of whether the number of digits in a group of binary digits is even. exchange The assembly of equipment in a communications system that controls the connec- tion of incoming and outgoing lines and includes the necessary signaling and supervisory func- tions. Different exchanges, or switches, can be colocated to perform different functions (e.g., local exchange/central office, tandem exchange, toll/trunk/transit exchange). extranet A network between partnering organizations. extranet VPN A VPN that allows an external organization to have defined access into an enterprise's internal networks and resources. F (fully associated) link A link that directly connects to signaling endpoints, generally SSPs. facility (1) Any or all of the physical elements of a plan used to provide communications ser- vices. (2) A component of an operating system. (3) A transmi