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The Identity Association Identifier (IAID) of a DHCP client, the client's MAC address for example, is added in client DHCP requests that a networking device relays to a DHCP server.



Acts as the clearing-house to assign and coordinate the use of numerous Internet protocol parameters such as Internet addresses, domain names, protocol numbers and more.


IAT histogram

In INM, the Inter-Arrival Time (IAT) histogram shows time intervals between the impulse noise clusters.



An IBSS, also called an Ad-hoc network, is defined as two or more computers with wireless adapters within range of each other that form an independent (wireless) network without the need of an access point (AP).



This is a card with the license key that allows you to activate services, such as content filtering, anti-virus, anti-spam and so on.



A message control and error-reporting protocol between a host server and a gateway to the Internet ICMP uses Internet Protocol (IP) datagram, but the messages are processed by the TCP/IP software and are not directly apparent to the application user.


ID Content

In IPSec, the ID type and ID content identify an individual Security Association (SA). The ID type can be a domain name, an IP address or an e-mail address. The ID content is the IP address, domain name, or e-mail address.


ID Type

In IPSec, the ID type and ID content identify an individual SA. The ID type can be a domain name, an IP address or an e-mail address. The ID content is the IP address, domain name, or e-mail address. When used with aggressive negotiation mode, the ID type and content allow an IPSec router to distinguish between SAs that connect from IPSec endpoints with dynamic IP addresses. For example, several telecommuters with dynamic IP addresses can use separate passwords to simultaneously connect to an IPSec router. With main negotiation mode, the ID type and content act as an extra level of identification for incoming SAs.


Identity Association (IA)

In Dynamic Host Configuration Protocol for IPv6 (DHCPv6), an Identity Association (IA) is a collection of addresses assigned to a DHCP client through which the server and client can manage a set of related IP addresses.


Identity Theft

Identity theft is the use of someone's personal information such as a credit card number or Social Security number, without the person's permission to commit fraud or other crimes. See also phishing.


Idle Mode

In WiMAX, idle mode allows a mobile station to receive broadcast messages over the network, without registering with any specific base station. This allows the MS to remain largely inactive, conserving power, but able to be reactivated with "paging" messages at any time.



An IDP system can detect malicious or suspicious packets and respond.


IDP - Host

Host IDPs are directly on the system being protected. They work closely with the operating system of the device on which they're installed.


IDP - Network

A Network IDP has at least two network interfaces, one internal and one external. As packets appear at an interface they are passed to the detection engine, which determines whether they are malicious or not. If a malicious packet is detected, an action is taken.



An Intrusion Detection System (IDS) can detect suspicious traffic, but does not take action against attacks. An IDS only raises an alert after the malicious payload has been delivered.


IEEE (The Institute of Electrical and Electronics Engineers)

 An independent institute that develops networking standards.


IEEE 802.11a

This wireless communication standard has a maximum transmission speed of 54 Mbps and a typical indoor range of 10 meters. It uses an operating frequency of 5 GHz.


IEEE 802.11b

This wireless communication standard has a maximum transmission speed of 11 Mbps and a typical indoor range of 30 meters. It uses an operating frequency of 2.4 GHz. This band may have to deal with interference from cordless telephones, Bluetooth devices, and various appliances.


IEEE 802.11g

This wireless communication standard has a maximum transmission speed of 54 Mbps and a typical indoor range of 30 meters. It uses an operating frequency of 2.4 GHz, and backward compatibility with 802.11b devices. This band may have to deal with interference from cordless telephones, Bluetooth devices, and various appliances.


IEEE 802.11h

The IEEE 802.11h standard defines two mechanisms (DFS and TPC) for IEEE 802.11a WLAN devices to avoid interference with other devices, such as satellites and military radar. See also DFS and TPC.


IEEE 802.11n

An IEEE wireless networking standard that significantly improves network throughput over previous standards, and offers backwards compatibility with 802.11b and 802.11g devices. 802.11n uses multiple receivers and transmitters, a technology known as MIMO (multiple input, multiple output).


IEEE 802.16

Institute of Electrical and Electronics Engineers wireless networking standard, also known as WiMAX, used in wireless metropolitan area networks (MANs).


IEEE 802.16e

An amendment to the IEEE 802.16 wireless networking standard, allowing mobile network access. Also known as Mobile WiMAX.


IEEE 802.1p

IEEE 802.1p specifies the user priority field and defines up to eight separate traffic types by inserting a tag into a MAC-layer frame that contains bits to define class of service.


IEEE 802.1Q

802.1Q is an IEEE standard for tagged VLANs (Virtual LANs) in which a VLAN tag is inserted into the layer-2 frame header to allow the creation of dynamic VLANs across switches. A VLAN tag includes the 12-bit VLAN ID and 3-bit user priority field.


IEEE 802.3af

This standard defines Power over Ethernet (PoE).


IEEE802.3 Flow Control

IEEE802.3 flow control is typically used with Ethernet ports operating in full duplex mode to send a pause signal to the sending port, causing it to temporarily stop sending signals when the receiving port's memory buffers are full.


IEEE 1588

IEEE 1588, also called Precise Time Protocol (PTP), is a protocol to synchronize the clocks of different devices over a network. Every slave device synchronizes to its master's clock by exchanging synchronization messages.


IGMP (Internet Group Management Protocol)

IGMP is a session-layer protocol used to establish membership in a multicast group - it is not used to carry user data. Refer to RFC 1112 and RFC 2236 for information on IGMP versions 1 and 2 respectively. See also Multicast.


IGMP Fast Leave

When a host wants to leave a multicast group (, it sends an IGMP leave message to inform its leaving to all routers ( in the multicast group. When a router receives the leave message, it sends a specific query message to all multicast group ( members to check if any other hosts are still in the group. Then the router deletes the host’s information. With IGMP fast leave enabled, the device will remove a host’s information from the group member list immediately once it receives a leave message from a host.


IGMP Filtering

The IGMP filtering feature controls which IGMP groups a subscriber on a port can join.


IGMP Group Limit

This feature limits the number of multicast groups a port is allowed to join.


IGMP Immediate Leave

An IGMP-enabled device removes a port from the multicast table immediately when an IGMP leave report is received on the port.


IGMP Join/Leave Reports

A host that wants to be a member of a multicast group sends an IGMP join report. When the host no longer wants to be a member of the multicast group, it sends an IGMP leave report.


IGMP Message Rate Limiting

Some DSLAMs can limit how many IGMP message packets a subscriber can send per second. This prevents subscribers from flooding the multicast server.


IGMP Proxy

An IGMP proxy device reduces multicast traffic by issuing IGMP host messages to a multicast router or server on behalf of the multicast hosts connected to the IGMP proxy device.


IGMP Query Message Discard

Some DSLAMs discard IGMP query messages received from subscriber ports. This prevents subscribers from hosting IGMP multicast servers.


IGMP Query and Report

A router sends an IGMP query to its downlink devices to create a multicast group member list (also called a multicast table). Then the devices that received the IGMP query sends the list to the router.

IGMP Snooping

IGMP snooping enables a layer-2 switch to dynamically learn the members of IP multicast groups. The switch can then forward multicast traffic to ports that are members of those multicast groups. When a switch receives multicast traffic destined for multicast groups that it does not know, it either forwards the traffic to all ports or discards it (depending on the switch and/or the switch's configuration). IGMP snooping generates no additional network traffic and allows a switch to handle multicast traffic more efficiently and effectively.


IGMP Statistics

Some DSLAMs record the number of active users in an IGMP multicast channel (multicast group) and also record IGMP message statistics on a per port basis to ease the ISP in management and troubleshooting.


IGMP Throttling

IGMP throttling controls how a switch deals with the IGMP reports when the maximum number of the IGMP groups a port can join is reached.



Internet Key Exchange is a two-phase security negotiation and key management service – phase 1 (Authentication) and phase 2 (Key Exchange). A phase 1 exchange establishes an IKE SA and phase 2 uses that SA to negotiate SAs for IPSec.



IM (Instant Messaging) refers to chat applications. Chat is real-time, text-based communication between two or more users via networked-connected devices.



IMA (Inverse Multiplexing for ATM) is a technology that can group several E1 or T1 lines and be applied to connect remote sites and the central office site together through an ATM network (as a backbone). IMA is used for increasing transmission speed.



Internet Message Access Protocol (IMAP) is a mail server protocol that e-mail clients use to retrieve e-mail. IMAP uses TCP or UDP port 143 by default.



IMAP over TLS/SSL (IMAPS) allows users to use TLS/SSL to create a secure IMAP connection for receiving e-mail. IMAPS uses TCP or UDP port 995 by default. See also IMAP, TLS, and SSL.



An International Mobile Equipment Identity (IMEI) is the serial number of a GSM or UMTS mobile device. It is used to identify the mobile device.


Impulse Noise Protection

Impulse noise protection creates a buffer to help protect the DSL physical layer connection against impulse noise. Sudden spikes in the lines noise level (impulse noise) can cause errors and result in lost packets. Impulse noise protection is recommended.



An International Mobile Subscriber Identity (IMSI) is stored in a SIM (Subscriber Identity Module) card. The IMSI is a unique number used to identify a user on a network.

In-band Management

In-band management means accessing the management interface of a device through a network port that is not a management port.


Incremental Archive

An incremental archive copies only source files that are new and/or modified since the last backup. The first backup is a full archive backup. The NSA also does a full backup at the backup interval you specify. The full backup is needed to be able to rest.



In later versions of the Simple Network Management Protocol (SNMP), an INFORM message is similar to a TRAP message; it is sent autonomously by an SNMP agent, usually to an SNMP manager. However, while a trap is sent and forgotten, the inform message requires a response from the target.


Infrastructure Mode

An infrastructure network is an integrated wireless and wired network. One or more APs link a wireless LAN to a wired LAN. This type of network topology is sometimes called an Extended Service Set (ESS).



Ingress is the act of entering something. An ingress port is an incoming port that a data packet enters from another port. An ingress router is a router through which a data packet enters a network from another network.


Initial Ranging

In WiMAX, a mobile station sends this request to claim its presence and synchronizes timing with the base station.



Proof that the data is the same as originally intended. Unauthorized software or people have not altered the original information.


Interface Grouping

By default, all LAN and WAN interfaces on a router are in the same group and can communicate with each other. Interface grouping allows you to create multiple groups and have the router assign the IP addresses in different domains to different groups.


Interface ID

In IPv6, an interface ID is a 64-bit identifier. It identifies a physical interface (for example, an Ethernet port) or a virtual interface (for example, the management IP address for a VLAN). One interface should have a unique interface ID.


Interlaced scan

Using interlaced scan, when images are capture, transmitted, and shown, every second line is used starting from the top and going to the bottom. For the second scan it repeats the process using the lines that were not used during the first scan. Interlaced video requires only half as much bandwidth as progressive scan, but has lower picture quality.


Interleave Delay

Interleave delay is the wait (in milliseconds) that determines the size of a single block of data to be interleaved (assembled) and then transmitted. Interleave delay is used when transmission error correction (Reed-Solomon) is necessary.

Internal Router

In OSPF, an Internal or intra-area router is a router in an area.


Internal SPTGEN

Internal SPTGEN lets you configure, save and upload multiple menus at the same time using just one configuration text file – eliminating the need to navigate and configure individual menus for each device.



The vast collection of inter-connected networks that use TCP/IP protocols evolved from the ARPANET (Advanced Research Projects Agency Network) of the late 1960’s and early 1970’s.

Any time you connect two or more networks together, you have an internet.


Internet Control Message Protocol for IPv6 (ICMPv6)

The Internet Control Message Protocol for IPv6 (ICMPv6 or ICMP for IPv6) is defined in RFC 4443. ICMPv6 has a preceding Next Header value of 58, which is different from the value used to identify ICMP for IPv4. IPv6 nodes use ICMPv6 to report errors.


Internet Protocol Television (IPTV)

Internet Protocol Television (IPTV) is a service with which you can subscribe in order to watch video hosted on media servers over the Internet in your television at home. An IPTV subscription gives you access to streaming media, such as Live TV or Video.



An intraframe, also known as a key frame, is a frame in which a complete image is stored in the data stream. Most videos have only small changes in the image from one frame to the next, so only changes between frames are stored in the data stream. Use of intraframes reduces the amount of information that needs to be stored.


Intra-BSS Traffic

This describes communication (through the AP) between two wireless clients within a wireless network.



A private network inside a company or organization that uses the same kinds of software that you would find on the public Internet, but that is only for internal use.



Person or software interested in breaking computer security to access, modify, or damage data.



Intrusions are attacks caused by malicious or suspicious packet(s) sent with the intent of causing harm, illegally accessing resources or interrupting service.


Intrusions - Host

The goal of host-based intrusions is to infiltrate files on an individual computer or server with the goal of accessing confidential information or destroying information on a computer.


Intrusion Lock

Intrusion locking is a security feature that stops unauthorized access to a port. If a cable is disconnected from the port, intrusion locking blocks access once a cable is reconnected.


Intrusion Policy ID

An intrusion policy ID identifies a unique intrusion signature.



Internet Protocol. A network and transport protocol used for exchanging data over the Internet. (Currently IP version 4 or IPv4) The underlying protocol for routing packets on the Internet and other TCP/IP-based networks.


IP Address

IP addresses identify individual devices on an IP network. Every networking device (including computers, servers, routers, printers, etc.) needs an IP address to communicate across the network. These networking devices are also known as hosts.


IP Alias

Internet Protocol Alias allows you to partition a physical network into logical networks over the same Ethernet interface.


IP Bridge

The IP bridge function is designed for large-scale, flat, access networks, and is ideal for Ethernet-based networks. When the IP bridge is enabled, the system forwards frames based on the destination IP address, instead of the destination MAC address.



 A Windows 2000 and XP utility that displays the IP address for a particular networking device.


IP Multicast

Traditionally, IP packets are transmitted in one of either two ways - Unicast (one sender to one recipient) or Broadcast (one sender to everybody on the network). IP Multicast is a third way to deliver IP packets to a group of hosts on the network - not everybody.



An IP PBX is a Private Branch Exchange (telephone switching system within an organization) that routes calls between VoIP (Voice over IP) users and between VoIP and traditional POTS users. See also POTS, VoIP, PBX.


IP Phone

IP phones are digital telephones used for Voice over IP (VoIP) applications. They perform digital / analog conversion on the incoming and outgoing audio. IP phones integrate into the existing IP network without additional equipment, and offer networking features (such as auto-provisioning and integration with a variety of Internet-based applications).


IP Policy Routing

Traditionally, routing is based on the destination address only and the router takes the shortest path to forward a packet. IP Policy Routing (IPPR) provides a mechanism to override the default routing behavior and forward the packet based on the policy defined by the network administrator.

Refers to the collective group of IP addresses located in any particular place (for example, LAN, WAN, Ethernet, etc.).


IP Precedence

Similar to IEEE 802.1p prioritization at layer-2, IP precedence uses three bits of the eight-bit ToS (Type of Service) field in the IP header to prioritize packets in a layer-3 network. There are eight classes of services (ranging from zero to seven) in IP precedence. Zero is the lowest priority level and seven is the highest.


IP Source Guard

IP source guard filters unauthorized DHCP and/or ARP packets in a network.


IP Source Route

Source routing makes use of an optional header to dictate the route an IP packet takes from source to destination. Network technicians may use it to time certain paths or for diagnostics. Most packets do not have a source route header.


IP Spoofing

IP spoofing is a technique used to gain unauthorized access to computers by tricking a router or firewall into thinking that the communications are coming from within the trusted network by modifying the packet headers.


IP Zero Length Attack

An IP Zero Length Attack is the flooding of the network by sending packets with zero data size.


IP-aware Bridging

"Some DSLAM line cards can forward frames based on the destination IP address, instead of the destination MAC address, and replace the source MAC address with the line card!|s own MAC address. This provides better scalability and security for large-scale



Allows changes to IP parameters such as the IP address.


IP/MAC Binding

IP address to MAC address binding helps ensure that only the intended devices get to use privileged IP addresses. The device assigns IP addresses by DHCP and records to which MAC address it assigns each IP address. The device then checks incoming connections.


iPass company

The iPass company handles authentication and accounting for mobile Internet users accessing the Internet through Wi-Fi hot spots that authenticate iPass clients through Wi-Fi based Wireless Internet Service Provider roaming (WISPr) compliant RADIUS servers.



IP Plug and Play allows a computer to access the Internet or a networking device without changing the network settings (such as IP address and subnet mask) of the computer, even when the IP addresses of the computer and the networking device are in different subnets.



Internet Protocol Security is a standards-based VPN (Virtual Private Network) that offers flexible solutions for secure data communications across a public network like the Internet. IPSec is built around a number of standardized cryptographic techniques to provide confidentiality, data integrity and authentication at the IP layer.


IPSec high availability

IPSec high availability (or VPN high availability) allows you to use a redundant VPN connection to another WAN interface on the remote IPSec router if the primary VPN connection goes down.


IPSec port forwarding

IPSec port forwarding for your VPN tunnels lets your IPSec router route traffic coming in through the VPN tunnel to IP addresses on the LAN based on port number to IP address mappings.



The Internet Protocol Television (IPTV) transmits television programs and video on demand (VOD) over the Internet or a broadband network using the Internet Protocol.



IPv6 (Internet Protocol, version 6) is designed to enhance IP address size and features. The increase in IPv6 address size to 128 bits (from the 32-bit IPv4 address) allows up to 3.4 x 1038 IP addresses.


IPv6 Caches

An IPv6 cache is a temporary storage area where an IPv6 host stores information from responses to its solicitation messages. An IPv6 host is required to have a neighbor cache, destination cache, prefix list and default router list.


IPv6 Loopback Address

An IPv6 loopback address (such as 0:0:0:0:0:0:0:1 or ::1) allows a host to send packets to itself. It is similar to “” in IPv4.


IPv6 Unspecified Address

An IPv6 unspecified address (such as 0:0:0:0:0:0:0:0 or ::) is used as the source address when a device does not have its own address. It is similiar to “” in IPv4.



The native NetWare internetworking protocol is IPX (Internetwork Packet Exchange). Like IP (Internet Protocol), IPX is an internetworking protocol that provides datagram services.



It is a way for multiple users on a system to “chat” over the network.



Infra-red Data Association (IrDA) is a protocol defining short-range, half-duplex, free-space infra-red line-of-sight communication between devices. IrDA is typically implemented in mobile devices such as cellphones and PDAs.



The Internet Research Task Force is composed of small research groups that work on Internet protocols, applications, architecture and technology.


ISDN BRI (Basic Rate Interface) Extension

An extension number assigned to an ISDN phone directly connected to a PBX, an ISDN or IPPBX device.


ISM bands

The Industrial, Scientific and Medical (ISM) bands are sections of the radio frequency (RF) spectrum originally reserved for unlicensed usage in the ISM fields. Networking standards that also operate in the ISM bands include IEEE 802.11a (5GHz), IEEE 802.11b/g (2.4GHz) and Bluetooth (2.4GHz).



The International Organization for Standardization is based in Geneva and is responsible for a wide range of standards including ones that apply to networking.


ISP (Internet Service Provider)

Provide connections into the Internet for home users and businesses. There are local, regional, national, and global ISPs. You can think of local ISPs as the gatekeepers into the Internet.



Refer to VoIP service provider.


iTunes Server

The iTunes server feature on an NSA device lets you use Apple’s iTunes software on your computers to play music and video files stored on the NSA.



The ITU-T is the primary international body for fostering cooperative standards for telecommunications equipment and systems. It was formerly known as the CCITT (Consultative Committee for International Telephony and Telegraphy).



Interactive Voice Response (IVR) is a phone technology that can detect voice and touch tones carried over a normal phone call and then respond with pre-recorded audio prompts to further direct callers on how to proceed. IVR systems can be used to control most functions where the interface can be broken down into a series of simple menu choices.