I
IBGP
Interior Border Gateway
Protocol. IBGP is the
BGP version used within an
AS.
IBSS
Independent Basic Service Set (see
BSS). An
IBSS is the 802.11 term for an ad-hoc network. See
ad-hoc mode.
ICMP
Internet Control Message Protocol. ICMP is the part of the TCP/IP protocol that allows
generation of error messages, test packets, and operating messages. For example, the ping
command allows you to send ICMP echo messages to a remote IP device to test for connectivity.
ICMP also supports traceroute, which identifies intermediate hops between a given source and
destination.
ICV
ICV (Integrity Check
Value) is a 4-byte code appended in standard
WEP to the 802.11 message. Enhanced WPA inserts an 8-byte MIC just before the ICV.
(See
WPA and
MIC.)
IEEE
Institute of Electrical and Electronic Engineers. This technical professional society
fosters the development of standards that often become national and international standards.
The organization publishes a number of journals and has many local chapters and several large
societies in special areas.
IETF
Internet Engineering Task Force. The IETF is a large, open, international community of
network designers, operators, vendors, and researchers concerned with the evolution of the
Internet architecture and the smooth operation of the Internet. The technical work of the IETF
is done in working groups, which are organized by topic.
IGMP
Internet Group Management Protocol. Hosts use IGMP to inform local routers of their
membership in multicast groups. Multicasting allows one computer on the Internet to send
content to multiple other computers that have identified themselves as interested in receiving
the originating computer's content. When all hosts leave a group, the router no longer
forwards packets that arrive for the multicast group.
IGMP snooping
This provides a method for intelligently forwarding multicast packets within a Layer 2
broadcast domain. By “snooping” the IGMP registration information, the device forms a
distribution list that determines which endstations receive packets with a specific multicast
address. Layer 2 switches listen for IGMP messages and build mapping tables and associated
forwarding filters. IGMP snooping also reduces IGMP protocol traffic.
IGP
Interior Gateway
Protocol. IGP refers to any protocol used to exchange routing information within an
AS. Examples of Internet IGPs include
RIP and
OSPF.
inline power
According to IEEE 802.3 af, inline power refers to providing an AC or DC power source
through the same cable as the data travels. It allows phones and network devices to be placed
in locations that are not near AC outlets. Most standard telephones use inline
power.
infrastructure
mode
An 802.11 networking
framework in which devices communicate with each other by first going through an access point.
In infrastructure mode, wireless devices can communicate with each other or can communicate
with a wired network. (See
ad-hoc mode and
BSS.)
intermediate
certificate
A certificate in the
middle of a certificate chain, that bridges the trust relationship between the server
certificate and the trusted certificate.
IP
Internet Protocol. The communications protocol underlying the Internet, IP allows
large, geographically diverse networks of computers to communicate with each other quickly and
economically over a variety of physical links; it is part of the TCP/IP suite of protocols. IP
is the Layer 3, or network layer, protocol that contains addressing and control information
that allows packets to be routed. IP is the most widely used networking protocol; it supports
the idea of unique addresses for each computer on the network. IP is a connectionless,
best-effort protocol; TCP reassembles the data after transmission. IP specifies the format and
addressing scheme for each packet.
IPC
Interprocess Communication. A capability supported by some operating systems that
allows one process to communicate with another process. The processes can be running on the
same computer or on different computers connected through a network.
IPsec/IPsec-ESP/IPsec-AH
Internet Protocol security (IPSec) |
Internet Protocol security. |
Encapsulating Security Payload (IPsec-ESP) |
The encapsulating security payload (ESP) encapsulates its data, enabling it to protect
data that follows in the datagram. |
Internet Protocol security Authentication Header (IPsec-AH) |
AH protects the parts of the IP datagram that can be predicted by the sender as it
will be received by the receiver. |
IPsec is a set of protocols developed by the IETF to support secure
exchange of packets at the IP layer. IPsec has been deployed widely to implement Virtual
Private Networks (VPNs).
IPsec supports two encryption modes: Transport and Tunnel. Transport
mode encrypts only the data portion (payload) of each packet, but leaves the header
untouched. The more secure Tunnel mode encrypts both the header and the payload. On the
receiving side, an IPSec-compliant device decrypts each packet.
For IPsec to work, the sending and receiving devices must share a public
key. This is accomplished through a protocol known as Internet Security Association and Key
Management Protocol/Oakley (ISAKMP/Oakley), which allows the receiver to obtain a public key
and authenticate the sender using digital certificates.
IPv6
Internet Protocol version 6. IPv6 is the next-generation IP protocol. The
specification was completed in 1997 by IETF. IPv6 is backward- compatible with and is designed
to fix the shortcomings of IPv4, such as data security and maximum number of user addresses.
IPv6 increases the address space from 32 to 128 bits, providing for an unlimited (for all
intents and purposes) number of networks and systems; IPv6 is expected to slowly replace IPv4,
with the two existing side by side for many years.
IP address
IP address is a 32-bit
number that identifies each unique sender or receiver of information that is sent in packets;
it is written as four octets separated by periods (dotted-decimal format). An IP address has
two parts: the identifier of a particular network and an identifier of the particular device
(which can be a server or a workstation) within that network. You may add an optional
sub-network identifier. Only the network part of the address is looked at between the routers
that move packets from one point to another along the network. Although you can have a static
IP address, many IP addresses are assigned dynamically from a pool. Many corporate networks
and online services economize on the number of IP addresses they use by sharing a pool of IP
addresses among a large number of users. (The format of the IP address is slightly changed in
IPv6.)
IPTV
Internal Protocol television. IPTV uses a digital signal sent via broadband through a
switched telephone or cable system. An accompanying set top box (that sits on top of the TV)
decodes the video and converts it to standard television signals.
IR
Internal router. In
OSPF, IR is an internal router that has all interfaces
within the same area.
IRDP
Internet Router Discovery Protocol. Used with IP, IRDP enables a host to determine the
address of a router that it can use as a default gateway. In Extreme Networks implementation,
IP multinetting requires a few changes for the IRDP.
ISO
This abbreviation is commonly used for the International Organization for
Standardization, although it is not an acronym. ISO was founded in 1946 and consists of
standards bodies from more than 75 nations. ISO had defined a number of important computer
standards, including the OSI reference model used as a standard architecture for
networking.
isochronous
Isochronous data is data (such as voice or video) that requires a constant
transmission rate, where data must be delivered within certain time constraints. For example,
multimedia streams require an isochronous transport mechanism to ensure that data is delivered
as fast as it is displayed and to ensure that the audio is synchronized with the video.
Compare: asynchronous processes in which data streams can be broken by random intervals, and
synchronous processes, in which data streams can be delivered only at specific
intervals.
ISP
An Internet Service
Provider is an organization that provides access to the Internet. Small ISPs provide service
via modem and ISDN while the larger ones also offer private line hookups (T1, fractional T1,
etc.). Customers are generally billed a fixed rate per month, but other charges may apply. For
a fee, a Web site can be created and maintained on the ISP's server, allowing the smaller
organization to have a presence on the Web with its own domain name.
ITU-T
International Telecommunication Union-Telecommunication. The ITU-T is the
telecommunications division of the ITU international standards body.
IV
Initialization Vector.
Part of the standard WEP encryption mechanism that concatenates a shared secret key with a
randomly generated 24-bit initialization vector. WPA with TKIP uses 48-bit IVs, an enhancement
that significantly increases the difficulty in cracking the encryption. (See
WPA and
TKIP.)