n LSR uses the label to index a forwarding table. m2m (machine-to-machine) A term that refers to the concept of communications between a device holding some amount of data that is of interest to another and another device that desires the use of that data. Telemetry is the most common implementation of m2m. Also sometimes stands for man-to-machine. MAC (Media Access Control) The part of OSI Layer 2 that describes how devices share access to the network. Token Ring, Ethernet, and FDDI are MAC-layer specifications. Wiring hubs primarily deal with MAC-layer equipment. macrocell A cell architecture in the cellular system that covered up to 8 miles (12.8 km) and used a lot of power, from 0.6 to 3 watts. This type of network was for fast-moving users, traveling distances of miles on their end-to-end journey. A macrocell could support up to about 60 users. MAE (metropolitan area exchange) An interconnection and exchange point where pub- lic Internet backbones meet and exchange traffic. Also called a NAP. mains powered Being powered by a permanent source such as an AC electrical power supply. MAN (metropolitan area network) A network that spans a geographical distance of up to a 62-mile (100-km) diameter; a citywide network. managed object A data-processing or data communications resource that can be managed through the use of an OSI management protocol. The resource itself need not be an OSI resource. A managed object may be a physical item of equipment, a software component, some abstract collection of information, or any combination of the three. MAPI (Messaging Application Programming Interface) A messaging API from Microsoft that consists of two components: Simple MAPI and Extended MAPI. Simple MAPI pro- vides hooks to various messaging systems, so developers can create message-enabled applica- tions by writing those applications to Simple MAPI rather than developing those hooks themselves. Extended MAPI is platform specific to Windows. mapping In network operations, the logical association of one set of values, suc