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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
hard rerouting
See connection recovery (page 33).
HDB3
See high-density binary 3 zero maximum encoding (HDB3) (page 60).
HDLC
See high-level data link control (HDLC) (page 61)
HDLC mode
See frame-cell trunk (page 54).
HDLC-transparent data service (HTDS)
A service that transports HDLC-framed data across the network without
interpretation, except that interframe flags are not transmitted. The efficiency
of the transmission is increased by not transmitting flags.
header error control (HEC)
A CRC code found in the last byte of the ATM cell header that is used for
verifying cell integrity.
hello packet
A type of PNNI routing packet that neighboring logical nodes exchange.
Hello protocol
The Hello protocol is a neighbor discovery protocol run over private network-
to-network interface (PNNI) links between lowest level nodes and logical
group nodes (LGNs).
HEP
See hot equipment protection (HEP) (page 62).
HG
See hunt group (HG) (page 62).
hierarchically complete source route
A stack of DTLs that represent a route across a PNNI routing domain. A DTL
is included for each hierarchical level between and including the current level
and the lowest visible level in which the source and destination nodes are
reachable.
high-density binary 3 zero maximum encoding (HDB3)
An encoding technique used to transfer bits over E1 and E3 lines. To ensure
1’s density, HDB3 substitutes a bipolar violation where four or more 0s are to
be sent in a row.