NETGEAR Cable/DSL ProSafe Firewall FR328S - Manual (Page 128)

FR328S ProSafe Firewall with Dial Back-Up Reference Manual v2
4 Glossary
M-10207-01, Reference Manual v2
recognizes the packet as belonging to a computer within its immediate neighborhood or domain. That
gateway then forwards the packet directly to the computer whose address is specified.
Because a message is divided into a number of packets, each packet can, if necessary, be sent by a different
route across the Internet. Packets can arrive in a different order than they were sent. The Internet Protocol
just delivers them. It's up to another protocol, the Transmission Control Protocol (TCP) to put them back in
the right order. IP is a connectionless protocol, which means that there is no continuing connection between
the end points that are communicating. Each packet that travels through the Internet is treated as an
independent unit of data without any relation to any other unit of data. (The reason the packets do get put in
the right order is because of TCP, the connection-oriented protocol that keeps track of the packet sequence in
a message.) In the Open Systems Interconnection (OSI) communication model, IP is in Layer 3, the
Networking Layer. The most widely used version of IP today is IP version 4 (IPv4). However, IP version 6
(IPv6) is also beginning to be supported. IPv6 provides for much longer addresses and therefore for the
possibility of many more Internet users. IPv6 includes the capabilities of IPv4 and any server that can
support IPv6 packets can also support IPv4 packets.
IP
See “Internet Protocol”
IP Address
A four-byte number uniquely defining each host on the Internet, usually written in dotted-decimal notation
with periods separating the bytes (for example, 134.177.244.57). Ranges of addresses are assigned by
Internic, an organization formed for this purpose.
ISP
Internet service provider.
LAN
See “Local Area Network”
Local Area Network
A communications network serving users within a limited area, such as one floor of a building. A LAN
typically connects multiple personal computers and shared network devices such as storage and printers.
Although many technologies exist to implement a LAN, Ethernet is the most common for connecting
personal computers and is limited to a distance of 1,500 feet. LANs can be connected together, but if
modems and telephones connect two or more LANs, the larger network constitutes what is called a WAN or
Wide Area Network.
MAC
(1) Medium Access Control. In LANs, the sublayer of the data link control layer that supports
medium-dependent functions and uses the services of the physical layer to provide services to the logical
link control (LLC) sublayer. The MAC sublayer includes the method of determining when a device has
access to the transmission medium. (2) Message Authentication Code. In computer security, a value that is a
part of a message or accompanies a message and is used to determine that the contents, origin, author, or
other attributes of all or part of the message are as they appear to be. (IBM Glossary of Computing Terms)