Nokia IP60 - Security Appliance, User Manual

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Glossary of Terms
486 Nokia IP60 Security Appliance User Guide
Subnet Mask
A 32-bit identifier indicating how the network is
split into subnets. The subnet mask indicates
which part of the IP address is the host ID and
which indicates the subnet.
T
TCP
TCP (Transmission Control Protocol) is a set of
rules (protocol) used along with the Internet
Protocol (IP) to send data in the form of
message units between computers over the
Internet. While IP takes care of handling the
actual delivery of the data, TCP takes care of
keeping track of the individual units of data
(called packets) that a message is divided into
for efficient routing through the Internet.
For example, when an HTML file is sent to you
from a Web server, the Transmission Control
Protocol (TCP) program layer in that server
divides the file into one or more packets,
numbers the packets, and then forwards them
individually to the IP program layer. Although
each packet has the same destination IP address,
it may get routed differently through the
network.
At the other end (the client program in your
computer), TCP reassembles the individual
packets and waits until they have arrived to
forward them to you as a single file.
TCP/IP
TCP/IP (Transmission Control Protocol/Internet
Protocol) is the underlying communication
protocol of the Internet.
U
UDP
UDP (User Datagram Protocol) is a
communications protocol that offers a limited
amount of service when messages are exchanged
between computers in a network that uses the
Internet Protocol (IP). UDP is an alternative to
the Transmission Control Protocol (TCP) and,
together with IP, is sometimes referred to as
UDP/IP. Like the Transmission Control
Protocol, UDP uses the Internet Protocol to
actually get a data unit (called a datagram) from
one computer to another. Unlike TCP, however,
UDP does not provide the service of dividing a
message into packets (datagrams) and
reassembling it at the other end.
UDP is often used for applications such as
streaming data.
URL
A URL (Uniform Resource Locator) is the
address of a file (resource) accessible on the
Internet. The type of resource depends on the
Internet application protocol. On the Web
(which uses the Hypertext Transfer Protocol), an
example of a URL is 'http://www.sofaware.com'.
V
VPN
A virtual private network (VPN) is a private data
network that makes use of the public
telecommunication infrastructure, maintaining
privacy through the use of a tunneling protocol
and security procedures.
VPN tunnel
A secure connection between a Remote Access
VPN Client and a Remote Access VPN Server.