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Glossary

(LES), LUNI is the ATM Forum's standard for LAN emulation on ATM net-
works. See also: LES and LECS.

MAC

Media Access Control: The lower sublayer in the Data Link layer, it

is responsible for hardware addressing, media access, and error detection of
frames. See also: Data Link layer and LLC.

MAC address

A Data Link layer hardware address that every port or

device needs in order to connect to a LAN segment. These addresses are used
by various devices in the network for accurate location of logical addresses.
MAC addresses are defined by the IEEE standard and their length is six char-
acters, typically using the burned-in address (BIA) of the local LAN inter-
face. Variously called hardware address, physical address, burned-in
address, or MAC-layer address.

MacIP

In AppleTalk, the network layer protocol encapsulating IP packets

in Datagram Delivery Protocol (DDP) packets. MacIP also supplies substi-
tute ARP services.

MAN

metropolitan area network: Any network that encompasses a met-

ropolitan area; that is, an area typically larger than a LAN but smaller than
a WAN. See also: LAN.

Manchester encoding

A method for digital coding in which a mid-bit

time transition is employed for clocking, and a 1 (one) is denoted by a high
voltage level during the first half of the bit time. This scheme is used by
Ethernet and IEEE 802.3.

maximum burst

Specified in bytes or cells, the largest burst of informa-

tion exceeding the insured rate that will be permitted on an ATM permanent
virtual connection for a short time and will not be dropped even if it goes
over the specified maximum rate. Compare with: insured burst. See also:
maximum rate.

maximum hop count

Number of routers a packet is allowed to pass

before it is terminated. This is created to prevent a packet from circling a
network forever.

maximum rate

The maximum permitted data throughput on a particular

virtual circuit, equal to the total of insured and uninsured traffic from the
traffic source. Should traffic congestion occur, uninsured information may
be deleted from the path. Measured in bits or cells per second, the maximum

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