A protocol that allows all network equipment to synchronize the date and time on the private or
internetwork environment.
network−to−network interface (NNI)
An interface that provides connectivity between two ATM switches.
non−blocking
A condition in which the fabric contains more bandwidth than the sum total of all the ports’
bandwidth combined.
nonvolatile RAM (NVRAM)
Static memory similar to that of the Flash. Information stored in the NVRAM does not get lost when
the power is cycled on the device. On a switch, the NVRAM stores the VLAN configuration, system
configuration, SNMP parameters, STP configuration, and configuration of each port.
Novell Directory Services (NDS)
The user, group, and security information database of network resources utilized in a NetWare 4.x
and/or NetWare 5.x internetwork.
O−P
Open System Interconnection (OSI) model
A seven−layer model created by the ISO to standardize and explain the interactions of networking
protocols.
oversubscription
A condition in which the total bandwidth of the ports is greater than the capacity of the switching
fabric. Also referred to as a blocking architecture.
Packet Internet Groper (PING)
A TCP/IP protocol−stack utility that works with Internet Control Message Protocol (ICMP) and uses
an echo request and reply to test connectivity to other systems.
password
A set of characters used with a username to authenticate a user on the network and to provide the user
with rights and permissions to files and resources.
patch panel
A device where the wiring used in coaxial or twisted−pair networks converges in a central location
and is then connected to the back of the panel.
peer−to−peer networking
A network environment without dedicated servers, where communication occurs between similarly
capable network nodes that act as both client and server.
permanent virtual circuit (PVC)
A logical path established in packet−switching networks between two locations. It’s similar to a
dedicated leased line. Also known as a permanent virtual connection in ATM terminology (not to be
confused with Private Virtual Circuit, also known as a PVC).
permission
Authorization provided to users, allowing them to access objects on the network. Network
administrators generally assign permissions. Slightly different from but often used with rights.
physical addressing scheme
The MAC address on every network card manufactured. It cannot be changed.
Physical layer
The bottom layer (Layer 1) of the OSI Reference Model, where all physical connectivity is defined.
plain old telephone service (POTS)
The current analog public telephone system. Also known as the PSTN.
Plug and Play
Architecture designed to allow hardware devices to be detected by the operating system and for the
driver to be automatically loaded.
Point−to−Point Protocol (PPP)
A common dial−up networking protocol that includes provisions for security and protocol negotiation
and provides host−to−network and switch−to−switch connections for one or more user sessions. PPP
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