User guide

D-10 Glossary
OSPF Open Shortest Path First, an interior gateway routing protocol
developed for IP networks based on the shortest path first or link-
state algorithm. Routers use link-state algorithms to send routing
information to all nodes in an internetwork by calculating the
shortest path to each node based on a topography of the Internet
constructed by each node. Each router sends that portion of the
routing table (keeps track of routes to particular network
destinations) that describes the state of its own links, and it also
sends the complete routing structure (topography). Using OSPF, a
host that obtains a change to a routing table or detects a change in
the network immediately multicasts the information to all other
hosts in the network so that all will have the same routing table
information. The host using OSPF sends only the part that has
changed, and only when a change has taken place. (RFC2328)
OUI Organizationally Unique Identifier (used in MAC addressing).
Packet The unit of data that is routed between an origin and a destination
on the Internet or any other packet-switched network. When any
file is sent from one place to another on the Internet, the
Transmission Control Protocol (TCP) layer of TCP/IP divides the
file into packets. Each packet is separately numbered and
includes the Internet address of the destination. The individual
packets for a given file may travel different routes through the
Internet. When they have all arrived, they are reassembled into
the original file (by the TCP layer at the receiving end).
PAP Password Authentication Protocol is the most basic form of
authentication, in which a user's name and password are
transmitted over a network and compared to a table of name-
password pairs. Typically, the passwords stored in the table are
encrypted. (See CHAP).
PDU Protocol Data Unit. A data object exchanged by protocol machines
(such as management stations, SMUX peers, and SNMP agents)
and consisting of both protocol control information and user data.
PDU is sometimes used as a synonym for “packet''.
PEAP PEAP (Protected Extensible Authentication Protocol) is an IETF
draft standard to authenticate wireless LAN clients without
requiring them to have certificates. In PEAP authentication, first
the user authenticates the authentication server, then the
authentication server authenticates the user. If the first phase is
successful, the user is then authenticated over the SSL tunnel
created in phase one using EAP-Generic Token Card (EAP-GTC)
or Microsoft Challenged Handshake Protocol Version 2 (MSCHAP
V2). (See also EAP-TLS).
PHP server Hypertext Preprocessor
PKI Public Key Infrastructure
PoE Power over Ethernet. The Power over Ethernet standard (802.3af)
defines how power can be provided to network devices over
existing Ethernet connection, eliminating the need for additional
external power supplies.
POST Power On Self Test, a diagnostic testing sequence performed by a
computer to determine if its hardware elements are present and
powered on. If so, the computer begins its boot sequence.
Term Definition