3Com CoreBuilder 7000 Operation Manual page 247

G 247
LOSSARY
quality of service class makes use of explicit forward congestion
indication.
Ethernet A CSMA/CD, 10 Mbps, local area data network, developed by Xerox
Corporation. It is one of the most popular baseband LANs in use.
ELAN name The name assigned an ELAN (Emulated Local Area Network).
ESI End System Identifier. This identifier distinguishes multiple nodes at the
same level in case the lower peer group is partitioned.
external clock Clock that comes through an RX channel into an on-board port.
external clock source The on-board port that supplies the external synchronization clock,
port which is distributed to all other on-board 8-port ports. Only a single
port of this type can exist in a box. Only on-board ports can function as
an external clock source port.
F
This is an advertising mechanism in PNNI and ensures that each node
flooding
maintains an identical topology database.
An address that does not match any of a given node's summary
foreign address
addresses.
H
horizontal links A link between two logical nodes that belong to the same peer group.
Protocol control information located at the beginning of a protocol
header
data unit.
Header Error Control. Using the fifth octet in the ATM cell header, ATM
HEC
equipment may check for an error and correct the contents of the
header. The check character is calculated using a CRC algorithm
allowing a single bit error in the header to be corrected or multiple
errors to be detected.
hello packet A type of PNNI routing packet that is exchanged between neighboring
logical nodes.
I