Lucent Technologies LambdaUnite Installation Manual page 332

Grooming
In telecommunications, the process of separating and segregating channels, as by combing, such
that the broadest channel possible can be assembled and sent across the longest practical link.
The aim is to minimize de-multiplexing traffic and reshuffling it electrically.
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H Hard Failure
An unrecoverable non-symptomatic (primary) failure that causes signal impairment or interferes
with critical network functions, such as DCC operation.
HDB3 (High Density Bipolar 3 Code)
Line code for 2 Mbit/s transmission systems.
HDLC (High Level Data Link Control)
OSI reference model datalink layer protocol.
HMI
Human Machine Interface
HML (Human Machine Language)
A standard language developed by the ITU for describing the interaction between humans and
dumb terminals.
HO
High Order
Holdover
An operating condition of a clock in which its local oscillator is not locked to an external
reference but is using storage techniques to maintain its accuracy with respect to the last known
frequency comparison with a synchronization reference.
Hot Standby
A circuit pack ready for fast, automatic placement into operation to replace an active circuit
pack. It has the same signal as the service going through it, so that choice is all that is required.
HPA (Higher Order Path Adaptation)
Function that adapts a lower order Virtual Container to a higher order Virtual Container by
processing the Tributary Unit pointer which indicates the phase of the lower order Virtual
Container Path Overhead relative to the higher order Virtual Container Path Overhead and
assembling/disassembling the complete higher order Virtual Container.
HPC (Higher Order Path Connection)
Function that provides for flexible assignment of higher order Virtual Containers within an
STM-N signal.
HPT (Higher Order Path Termination)
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G L O S S A R Y
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Lucent Technologies 365-374-059
Issue a, January 2002