Interphase Tech iSPAN - Manual (Page 225)

iSPAN Serial WAN Adapter Users Guide 205
NI-1 (National ISDN1) ◆ A specification for a standard ISDN phone
line. National ISDN 1 is intended to be a set of standards to which
every manufacturer's equipment should conform for maximum
interoperability. NI-2 and NI-3 are future standards currently under
development.
NRZI (Non Return to Zero Inverted) ◆ Encoding technique in which a
change in state represents 0. Also known as invert-on-zero coding.
NSAP (Network Services Access Point) ◆ In the OSI environment, it
is the SAP between the network and the transport layers. It identifies a
Data Terminal Equipment by a unique address.
NT1 (Network Termination 1) ◆ The device that connects to your
ISDN hardware and also works as a converter between an ISDN U-
interface and an ISDN S/T-Interface. An NT1 converts a line from a 2-
wire to a 4-wire connection. Some ISDN adapters have a NT1 already
built into them.
NT2 (Network Termination 2) ◆ An NT2 handles termination for mul-
tiple B channels on a PRI line. NT2s are typically found embedded into
PBXs or switches on network servers which support Primary Rate
Interface (PRI).
OSI (Open Systems Interconnection) Model ◆ The 7-layer protocol
model defined by the ISO for data communications.
PABX ◆ Private Automatic Branch Exchange.
PBX (Private Branch Exchange) ◆ PBX is a private telephone
switch. It is connected to groups of lines from one or more central
offices and to all of the telephones at the location served by the PBX.
PCI (Peripheral Component Interconnect) (bus) ◆ A high-perfor-
mance multiplexed address and data bus. Supporting 32-bit with
optional 64-bit data transfers, the PCI bus is intended to be an intercon-
nect between peripheral controllers, peripheral add-in boards, and pro-
cessor/memory systems. The PCI bus operates at up to 66 MHz,
providing burst transfer rates up to 264 MBps 32 bits wide, or up to 528
MBps 64 bits wide.
PDU (Protocol Data Unit) ◆ Data in a highly-structured format for the
purpose of transmission. Frame, packet, and PDU are equivalent in
most contexts.
PHY (Physical Layer) ◆ Layer 1 of the OSI model. Defines and han-
dles the electrical and physical connections between systems. The
Physical layer can also encode data in a form that is compatible with
the medium (coaxial, twisted pair, fiber, and so on).