Ericsson HL950 Administrator's Manual page 154

Multi Service Edge Device HL950
Administrator's Guide
NAT – Network Address Translation
NMC – Network Management Center
OAM – Operations, Administration and Maintenance
OAM includes network maintenance features such as connectivity verification, alarm surveillance,
continuity checking and performance monitoring.
Packet filtering
Is access control at the Internet Protocol layer. This includes accepting or rejecting (dropping) frames
of data based on source and destination addresses. This is a very basic filtering method that does not
include using passwords or authentication algorithms.
Packet switching
Refers to protocols in which messages are divided into packets before they are sent. Each packet is
then transmitted individually and can even follow different routes to its destination. Once all packets
forming a message arrive at the destination, they are recompiled into the original message Most
modern WAN protocols, including TCP/IP, X.25 and Frame Relay are based on packet-switching
technologies.
PAT – Port Address Translation
PBX – Private Branch Exchange
A private telephone network used within an enterprise. Users of the PBX share a certain number of
outside lines for making telephone calls external to the PBX.
PDA – Personal Digital Assistant
PDU – Protocol Data Unit
The PDU is the unit of data in the OSI Reference Model. It contains both protocol-control information
and user data from the layer above and allows the two processes to coordinate interactions.
PHY – Physical Interface
Ping of death
Is a denial of service attack that relies upon TCP/IP's difficulty handling unusually large ping packets.
If not protected, a system that receives an oversize ping packet may hang or crash.
PNO – Public Network Operator
POTS – Plain Old Telephone Service
Refers to the standard telephone service that most homes use. See also PSTN.
PPP – Point-to-Point Protocol
A protocol that allows a computer to use TCP/IP with a standard telephone line and a high-speed
modem to establish a link between two (and only two) terminal installations.
PRI – Primary-Rate Interface
EN/LZT 108 5995 R3
June 2003
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