Cisco Systems Cisco uBR10012 manual GL-7

IOS

IP

IP multicast

IR

ISP

ITU-T

Glossary

Internet Operating System. See Cisco IOS.

Internet Protocol. Network layer protocol in the TCP/IP stack offering a connectionless internetwork service. IP provides features for addressing, type-of-service specification, fragmentation and reassembly, and security. Defined in RFC 791.

Routing technique that allows IP traffic to be propagated from one source to a number of destinations or from many sources to many destinations. Rather than sending one packet to each destination, one packet is sent to a multicast group identified by a single IP destination group address.

Intermediate reach. SONET/SDH specification for transmit power and receive sensitivity that achieves a 9.3-mile (15-km) reach.

Internet Service Provider. A company that provides Internet access to other companies and individuals.

International Telecommunication Union Telecommunication Standardization Sector. International body that develops worldwide standards for telecommunications technologies. The ITU-T carries out the functions of the former CCITT.

L

LAN	Local-area network. High-speed, low-error data network covering a relatively small geographic area
	(up to a few thousand meters). LANs connect workstations, peripherals, terminals, and other devices
	in a single building or some other geographically limited area. LAN standards specify cabling and
	signaling at the physical and data link layers of the OSI model. Ethernet, FDDI, and Token Ring are
	widely used LAN technologies. Compare with MAN and WAN.

Line card

LMI

Any I/O card that can be inserted in a modular chassis.

Local Management Interface. A set of enhancements to the basic Frame Relay specification. LMI includes support for a keepalive mechanism, which verifies that data is flowing; a multicast mechanism, which provides the network server with its local DLCI and the multicast DLCI; global addressing, which gives DLCIs global rather than local significance in Frame Relay networks; and a status mechanism, which provides an on-going status report on the DLCIs known to the switch. Known as LMT in ANSI terminology.

Local-area network

Loopback test

LOS

See LAN.

A test in which signals are sent and then directed back toward their source from some point along the communications path. Loopback tests are often used to test network interface usability.

Loss of signal. A SONET port status indicator that activates when an LOS defect occurs and does not clear throughout the alarm integration period, which is typically 2.5 seconds. An LOS defect occurs when the OC-3 port receives all zeros for 20 microseconds (+.3 ms). This occurrence begins the alarm integration period. If this period elapses without the detection of two consecutive frames in which there are no 20-ms periods of signal loss, the LOS indicator activates. The LOS indicator clears when an LOS defect is not detected for an interval equal to the alarm deactivation period (typically 10 seconds).

	Cisco uBR10012 Universal Broadband Router Hardware Installation Guide
OL-18259-01		GL-7