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ForeRunner

ATM Switch Network Configuration Manual

Glossary - 21

Gl
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Glossary

Logical Link Control (LLC) -

protocol developed by the IEEE 802 committee for data-link-layer

transmission control; the upper sublayer of the IEEE Layer 2 (OSI) protocol that complements
the MAC protocol; IEEE standard 802.2; includes end-system addressing and error checking.

Loopback -

a troubleshooting technique that returns a transmitted signal to its source so that

the signal can be analyzed for errors. Typically, a loopback is set at various points in a line
until the section of the line that is causing the problem is discovered.

looptest -

program that tests an interface for basic cell reception and transmission functional-

ity, usually used for diagnostic purposes to determine if an interface is functioning properly.

Loss Of Frame (LOF) -

a type of transmission error that may occur in wide-area carrier lines.

Loss Of Pointer (LOP) -

a type of transmission error that may occur in wide-area carrier lines.

Loss Of Signal (LOS) -

a type of transmission error that may occur in wide-area carrier lines, or

a condition declared when the DTE senses a loss of a DS1 signal from the CPE for more the 150
milliseconds (the DTE generally responds with an all ones “Blue or AIS” signal).

Management Information Base (MIB) -

the set of parameters that an SNMP management station

can query or set in the SNMP agent of a networked device (e.g., router).

Maximum Burst Size (MBS) -

the Burst Tolerance (BT) is conveyed through the MBS which is

coded as a number of cells. The BT together with the SCR and the GCRA determine the MBS
that may be transmitted at the peak rate and still be in conformance with the GCRA.

Maximum Burst Tolerance -

the largest burst of data that a network device is guaranteed to

handle without discarding cells or packets. Bursts of data larger than the maximum burst size
may be subject to discard.

Maximum Cell Delay Variance (MCDV) -

This is the maximum two-point CDV objective across a

link or node for the specified service category.

Maximum Cell Loss Ratio (MCLR) -

This is the maximum ratio of the number of cells that do not

make it across the link or node to the total number of cells arriving at the link or node.

Maximum Cell Transfer Delay (MCTD) -

This is the sum of the fixed delay component across the

link or node and MCDV.

Maximum Transmission Unit (MTU) -

the largest unit of data that can be sent over a type of

physical medium.

Mbps -

megabits per second (million)

Media Access Control (MAC) -

a media-specific access control protocol within IEEE 802 specifi-

cations; currently includes variations for Token Ring, token bus, and CSMA/CD; the lower
sublayer of the IEEE’s link layer (OSI), which complements the Logical Link Control (LLC).

Media Attachment Unit (MAU) -

device used in Ethernet and IEEE 802.3 networks that provides

the interface between the AUI port of a station and the common medium of the Ethernet. The
MAU, which can be built into a station or can be a separate device, performs physical layer
functions including conversion of the digital data from the Ethernet interface, collision detec-
tion, and injection of bits onto the network.