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Glossary

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research, it has become a medium for exchanging and distributing informa-
tion of all kinds. The Internet's need to link disparate computer platforms
and technologies has led to the development of uniform protocols and stan-
dards that have also found widespread use within corporate LANs. See also:
TCP/IP and MBONE.

internet

Before the rise in the use of the Internet, this lowercase form was

shorthand for "internetwork" in the generic sense. Now rarely used. See
also: internetwork.

Internet protocol

Any protocol belonging to the TCP/IP protocol stack.

See also: TCP/IP.

internetwork

Any group of private networks interconnected by routers

and other mechanisms, typically operating as a single entity.

internetworking

Broadly, anything associated with the general task of

linking networks to each other. The term encompasses technologies, proce-
dures, and products. When you connect networks to a router, you are cre-
ating an internetwork.

inter-VLAN routing

Cisco has created the proprietary protocol Inter-

Switch Link (ISL) to allow routing between VLANs with only one Ethernet
interface. To run ISL, you need to have two VLAN-capable FastEthernet or
Gigabit Ethernet devices like a Cisco 5000 switch and a 7000 series router.

intra-area routing

Routing that occurs within a logical area. Contrast

with: interarea routing.

intruder detection

Intruder detection systems operate by monitoring the

data flow for characteristics consistent with security threats. In this manner,
an intruder can be monitored or blocked from access. One trigger for an
intruder detection system is multiple ping packets from a single resource in
a brief period of time.

Inverse ARP

Inverse Address Resolution Protocol: A technique by which

dynamic mappings are constructed in a network, allowing a device such as
a router to locate the logical network address and associate it with a perma-
nent virtual circuit (PVC). Commonly used in Frame Relay to determine the
far-end node's TCP/IP address by sending the Inverse ARP request to the
local DLCI.

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