Glossary E-13
node
An IPX/IGX/BPX switch serving as a connection point to the network. At a node, connections
from service lines are routed to trunks for transmission to other nodes in the network.
NPC (Network Processor Card)
Micro-processor based system controller front card that contains the software used to operate the
IPX switch.
NPM (Network Processor Module)
Micro-processor based system controller front card that contains the software used to operate the
IGX switch.
Nrm
Maximum number of cells a source may send for each forward RM cell, i.e., an RM cell must be
sent for every Nrm-1 data cells.
NTC (Network Trunk Card)
IPX front card that coordinates fastpacket trunk traffic to another node via a number of
backcards: T1, E1, Y1, and subrate (RS449, X.21, and V.35).
NTM (Network Trunk Module)
IGX front card that coordinates fastpacket trunk traffic to another node via a number of
backcards: T1, E1, Y1, and subrate (RS449, X.21, and V.35).
O
OC-3
Standard optical transmission facility rate of 155.20 Mbps.
OCC (Other Common Carrier)
In the United States, reference to all the other telecommunications companies providing various
transmission services other than AT&T.
P
packet line
Packet line referred to a line used to carry FastPackets between IPX nodes in a network. The term
in these documents is replaced by the more general “trunk” which is defined as a physical link
from node to node, node to shelf, or node to network. The trunk may be one that supports 24-byte
FastPackets (packet trunk), or one that supports 53 byte ATM cells (cell trunk).
packet switching
A system that breaks data strings into small units (packets), then individually addresses and
routes them through the network.
PAD (Packet Assembler/Disassembler)
A device that converts a serial data stream into discrete packets in the transmit direction and
converts the received packets back into a serial data stream. Adds header information in the
transmit packet to allow it to be routed to the proper destination.
