Glossary
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Cisco uBR10012 Universal Broadband Router Hardware Installation Guide
78-11450-03 Rev.B0
M
M13 Generic term for equipment that multiplexes DS1s into DS3s. Sometimes used to describe a specific
DS3 multiplex format. Some standards use this term to describe a synchronous multiplexing format
also know as SYNTRAN. In many cases M13 does not refer to the SYNTRAN format, but instead
refers to the format also known as M23.
M23 A method of multiplexing four DS1 signals into a DS2 signal, then multiplexing seven DS2 signals into
a DS3 signal.
MAC Media Access Control. Lower of the two sublayers of the data link layer defined by the IEEE. The MAC
sublayer handles access to shared media.
MAC address Standardized data link layer address that is required for each port or device that connects to a LAN.
Other devices in the network use these addresses to locate specific ports in the network, and to create
and update routing tables and data structures. MAC addresses are 6 bytes long and are controlled by
the IEEE. Also known as a hardware address, MAC-layer address, or physical address.
Major alarm One of a group of alarm conditions that are considered the second most severe of all reportable alarms.
Major alarms affect several subscribers who connect to the reporting node. You can use the show
facility-alarm status IOS command to obtain more information about the problem. See also Critical
alarm and Minor alarm.
MAN Metropolitan-area network. A network that spans a metropolitan area. Generally, a MAN spans a larger
geographic area than a LAN, but a smaller geographic area than a WAN. Compare with LAN and WAN.
Management
Information Base
See MIB.
Media Access
Control
See MAC.
Metropolitan-area
network
See MAN.
MIB Management Information Base. Database of network management information that is used and
maintained by a network management protocol such as SNMP or CMIP. The value of a MIB object can
be changed or retrieved using SNMP or CMIP commands, usually through a GUI-based network
management system. MIB objects are organized in a tree structure that includes public (standard) and
private (proprietary) branches.
Minor alarm One of a group of alarm conditions that are considered the third most severe of all reportable alarms.
Minor alarms affect a single or small number of subscribers who connect to the reporting node. You
can use the show facility-alarm status IOS command to obtain more information about the problem.
See also Critical alarm and Major alarm.
MLP Multilink Point-to-Point Protocol. A method of splitting, recombining, and sequencing datagrams
across multiple logical data links.
MMF Multimode fiber. Optical fiber supporting propagation of multiple frequencies of light. See also
Single-mode fiber.
MPLS Multiprotocol Label Switching. An emerging industry standard upon which tag switching is based.