3Com CoreBuilder 7000, Operation Manual

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G
LOSSARY
245
C
call An association between two or more users or between a user and a
network entity that is established by the use of network capabilities.
This association may have zero or more connections.
cell
An ATM Layer protocol data unit (PDU) characterized by fixed, rather
than variable, length payloads.
cell delay variation A quantification of cell clumping for a connection. The cell clumping
CDV (
y
k
), is defined as the difference between a cell’s expected
reference arrival time ( c
k
) and its actual arrival time ( a
k
). The expected
reference arrival time ( c
k
) of cell k of a specific connection is
max[ck-1+T,ak] . T is the reciprocal of the negotiated peak cell rate.
cell loss ratio In a network/network element, cell loss ratio is (1-x/y), where y is the
number of cells that arrive in an interval at the ingress of the
network/network element; and x is the number of these y cells that
leave at the egress of the network/network element.
CoreBuilder 7000
The 3Com CoreBuilder 7000/7000HD switch is a high-performance,
modular ATM switch.
CLP Cell Loss Priority. A bit in the ATM cell header indicating that if there is
a need to discard a cell, the cell with the CLP bit marked is to be
discarded.
CLR Cell Loss Ratio. CLR is a negotiated QoS parameter and acceptable
values are network specific. The objective is to minimize CLR provided
the end-system adapts the traffic to the changing ATM layer transfer
characteristics. The Cell Loss Ratio is defined for a connection as: Lost
Cells/Total Transmitted Cells.
collision Overlapping transmission of two or more nodes onto media. All data is
unusable.
connection
An ATM connection consists of the concatenation of ATM Layer links in
order to provide an end-to-end information transfer capability to access
points.
connectionless
communications
A form of packet-switching that relies on global addresses in each
packet rather than on predefined virtual circuits.