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List of terms
Nortel Multiservice Switch 7400/15000/20000
Terminology
NN10600-005 7.2S1 Standard
PCR7.2 and up March 2006
Copyright © 2006, Nortel Nortel Confidential
high-level data link control (HDLC)
An ITU-TSS link layer protocol standard for point-to-point and multipoint
communications.
high-speed serial interface (HSSI)
An EIA/TIA-613 physical layer standard. Similar to V.35 and V.11, HSSI is an
interchange circuit that transfers serial data between DTE and DCE at speeds
ranging from 1 Mbit/s to 52 Mbit/s.
hitless CP switchover
The switch of activity from the active CP to a standby CP without restarting the
FPs on the shelf. FPs that support hitless CP switchover continue,
uninterrupted, to provide service. FPs that do not support hitless CP
switchover must restart and do not provide uninterrupted service.
hitless services
1 A service is hitless when the software that provides the service can run
uninterrupted, even when the hardware providing the service changes.
With hitless services, traffic incurs minimal interruption and established
connections stay up. Nortel Multiservice Switch software applications and
features are categorized based on their ability to provide hitless services.
2 See cold standby (page 30).
3 See hot standby (page 62).
4 See warm standby (page 148).
hitless software migration (HSM)
Hitless software migration allows a shelf (CPs and FPs) to migrate from one
version of software to another without interrupting the services being provided
by that shelf.
holding priority (HP)
In an ATM network, a priority scheme that is assigned to all bandwidth non-
elastic ATM connections to indicate the relative importance of each
connection. When a loss of bandwidth occurs, connections with lower holding
priority are released first.
In a PORS network, a parameter that indicates the tolerance of a connection
for path bumping. A connection with a lower holding priority can be bumped to
an alternative path or terminated by a connection with a higher priority.
hop by hop route
A routing approach in which each node along the path uses its own routing
knowledge to determine the next hop of the route. The expectation is that all
nodes choose consistent hops so that the call reaches the requested
destination.