10-Mbps baseband Ethernet specification using 50-ohm thin coaxial cable. 10Base2, which is part of the IEEE 802.3 specification, has a distance limit of 185 meters per segment.
10 Base5
10-Mbps baseband Ethernet specification using standard (thick) 50-ohm baseband coaxial cable. 10Base5, which is part of the IEEE 802.3 baseband physical layer specification, has a distance limit of 500 meters per segment.
10 BaseF
10-Mbps baseband Ethernet specification that refers to the 10BaseFB, 10BaseFL, and 10BaseFP standards for Ethernet over fiber-optic cabling.
10 BaseFB
10-Mbps baseband Ethernet specification using fiber-optic cabling. 10BaseFB is part of the IEEE 10BaseF specification. It is not used to connect user stations, but instead provides a synchronous signaling backbone that allows additional segments and repeaters to be connected to the network. 10BaseFB segments can be up to 2,000 meters long.
10BaseFL
10-Mbps baseband Ethernet specification using fiber-optic cabling. 10BaseFL is part of the IEEE10BaseF specification and, while able to interoperate with FOIRL, is designed to replace the FOIRL specification. 10BaseFL segments can be up to 1,000 meters long if used with FOIRL, and up to 2,000 meters if 10BaseFL is used exclusively.
10 BaseFP
10-Mbps fiber-passive baseband Ethernet specification using fiber-optic cabling. 10BaseFP ispart of the IEEE 10BaseF specification. It organizes a number of computers into a star topology without the use of repeaters. 10Base FP segments can be up to 500 meters long.
10 BaseT
A specification of the IEEE 802.3 committee for the implementation of 10 Mbit Ethernet on unshielded twisted pair wiring.
10 Broad36
10-Mbps broadband Ethernet specification using broadband coaxial cable. 10Broad36, which is part of the IEEE 802.3 specification, has a distance limit of 3,600 meters per segment.
100 BaseFX
100-Mbps baseband Fast Ethernet specification using two strands of multimode fiber-optic cable per link. To guarantee proper signal timing, a 100BaseFX link exceed 400 meters in length. Based on the IEEE 802.3 standard.
100 BaseT
A 100MB Ethernet specification using Level 5 UTP.
100 BaseT4
100-Mbps baseband Fast Ethernet specification using four pairs of Category 3, 4, or 5UTP wiring. To guarantee proper signal timing, a 100BaseT4 segment cannot exceed 100 meters in length. Based on the IEEE 802.3 standard.
100 BaseTX
100-Mbps baseband Fast Ethernet specification using two pairs of either UTP or STP wiring. The first pair of wires is used to receive data, the second is used to transmit. To guarantee proper signal timing a 100BaseTX segment cannot exceed 100 meters in length. Based on the IEEE 802.3 standard.
100 BaseX
100-Mbps baseband Fast Ethernet specification that refers to the 100BaseFX and 100BaseTX standards for Fast Ethernet over fiber-optic cabling. Based on the IEEE 802.3 standard.
100VG-AnyLAN
100-Mbps Fast Ethernet and Token Ring media technology using four pairs of Category 3, 4, or 5 UTP cabling. This high-speed transport technology, developed by Hewlett-Packard, can be made to operate on existing 10BaseT Ethernet networks. Based on the IEEE 802.12 standard.
4B/5B local fiber
4-byte/5-byte loc 100 Mbps over multimode fiber. See also TAXI 4B/5B.
08/10B local fiber
8-byte/10-byte local fiber. Fiber channel physical media that supports speeds up to 149.76 Mbps over multimode fiber.
2B1Q(Two Binary, One Quarternary )
Two Binary, One Quarternary transmission is an amplitude modulation scheme for DC pulses. Itcombines two bits at a time to represent one of four amplitude levels. 2B1Q coding is defined in ANSI T1.601 and ETR 080, Annex A.
802.1Q(IEEE 802.1Q VLAN)
802.1Q is an IEEE standard for tagged VLANs (Virtual LANs) in which a VLAN ID is inserted into the layer-2 frame header to allow the creation of dynamic VLANs across switches. Tagged VLANs are not confined to the switch on which they were created as are port-based VLANs.
This is the end of a VPN tunnel opposite the Z-end (see also Z-end).
A-Law
A-Law and Mu-Law are Pulse Code Modulation (PCM) techniques that dictate forms of compression
for audio signals. They are widely-used standard methods of coding voice as they improve signal-to-noise
ratio without increasing the amount of data. Mu-Law is a standard in North America; A-Law in Europe.
AAL(ATM Adaptation Layer)
AAL converges packets from upper layers into ATM cells as defined by ITU-T, ETSI and the ATM
Forum. AAL has several service types and classes of operation to accommodate different types of classes.
AAL-2(ATM Adaptation Layer - Type 2)
A connection oriented, VBR (Variable Bit Rate) protocol for real-time applications. It is similar to T1
or T3 and provides a variety of data rates. See AAL.
AAL-5(ATM Adaptation Layer - Type 5)
A UBR (Unspecified Bit Rate) protocol that provid spare bandwidth to non-critical services such as
file transfers. See AAL.
ABR(Available Bit Rate)
This is a guaranteed minimum data transfer rate. Higher rates are allowed if there is extra bandwidth
available on the network.
Access Line
This is the physical telecommunications circuit (line) in the local network that connects the CO (Central Office)
with the customer's residence. See also Local Loop.
Access Point
An Access Point (AP) is a network device that acts as a bridge between a wired and a wireless network.
When connected to an Internet service gateway device, an account generator printer allows you to create and
print out subscriber accounts automatically. The account generator printer is also known as the statement printer.
Acknowledged Alarms
This means that an administrator has decided to handle the cause of this alarm. Other administrators
see that person's name in their alarm screen, thus avoiding duplicate effort to solve the same problem.
Active Alarms
"Active" is the initial state of an alarm, which means the alarm is new and an administrator is yet to
assume responsibility for handling it.
Ad-Hoc(Ad-Hoc Wireless LAN)
An Ad-Hoc wireless LAN is a group of computers that uses wireless LAN cards, to connect as an
independent wireless LAN. An Ad-Hoc wireless LAN is sometimes referred to as a Basic Service Set (BSS).
ADPCM-32 is a 32-bit voice compression method that converts analog signals to digital data, thus
allowing voice transmission over digital lines.
ADSL(Asymmetrical Digital Subscriber Line )
This is an asymmetrical technology which means that the downstream data rate of the line is much
higher than the upstream data rate. ADSL operates in a frequency range that is above the frequency
range of voice services, so both can operate over the same cable.
AES(Advanced Encryption Standard)
Advanced Encryption Standard is method of data encryption that uses a secret key. AES may use
a 128-bit, 192-bit or 256-bit key. AES is faster than 3DES.
Aggressive Mode
Aggressive mode is an IPSec phase 1 negotiation mode (see Negotiation Mode). Aggressive mode is quicker than Main Mode because it eliminates several steps. However the faster speed limits its negotiating power and it also does not provide identity protection. See also Main Mode.
AH(Authentication Header)
Authentication Header (RFC 2402) is a protocol that IPSec uses to verify integrity of a data packet (including the header) and the identity of it's ender.
Always-On
Always-on refers to broadband services that are connected all the time, eliminating the need to dial-up to connect.
Analog
An electrical circuit that is represented by means of continuous, variable physical quantities (such as voltages
and frequencies), as opposed to discrete representations (like the 0/1, off/on representation of digital circuits).
ANSI(American National Standards Institute)
ANSI is the primary organization for fostering the development of technology standards
(defining coding standards and signaling schemes) in the United States.
ANSI Mode
This is a VDSL mode that operates in a specific frequency band allocation with associated upstream
and downstream speeds.
Antenna
An antenna acts as a radiator that propagates a radio frequency signal from a wireless device
through the air. An antenna also works in reverse by capturing signals from the air.
ARP(Address Resolution Protocol)
Address Resolution Protocol is a protocol for mapping an Internet Protocol address
(IP address) to a physical computer address that is recognized in the local network.
ASIC(Application Specific Integrated Circuit)
This is a chip engineered for a particular use or function.
AT&T 5ESS
A digital central office switching system made by AT&T.
ATM(Asynchronous Transfer Mode.)
ATM is a LAN and WAN networking technology that provides high-speed data transfer.
ATM uses fixed-size packets of information called cells. With ATM, a high
QoS (Quality of Service) can be guaranteed.
ATM25
ATM25 is a 25.6 Mbps cell-based user interface defined by the ATM Forum.
ATU-C(ADSL Transmission Unit-CO)
This is the hardware at the CO (Central Office) that terminates an ADSL connection.
ATU-R(ADSL Transmission Unit-Remote)
This is the hardware at a customer's location that provides termination for an ADSL connection.
Authentication Algorithm
This is an established, step-by-step procedure for verifying the identity of a packet's ender.
Authenticity
Proof that the information came from the person or location that reportedly sent it. One
example of authenticating software is through digital signatures.
Auto-Crossover
An auto-crossover Ethernet port enables you to use either a crossover Ethernet cable or a straight-through Ethernet cable to connect your device to either a computer or external hub.
In other words these ports automatically adjust according to the type of cable so that either straight-through Ethernet cable or crossover Ethernet cable may be used.
Auto-MDI (Medium Dependent Interface)/MDIX (MDI crossover) is an Ethernet port feature
that automatically adjusts to crossover or straight-through Ethernet cable so you can use either
to connect your device to a computer or a switch/external hub. See also auto-crossover.
Auxiliary Port
This port can be used as a traditional dial-up connection in reserve if ever the broadband connection
to the WAN port fails. See also Dial Backup.
This is the bearer channel in an ISDN connection. B channel is a 64 Kbps full-duplex channel
in both primary and basic rate ISDN.
Back Door
A deliberately planned security breach in a program that allows special access to a computer or program.
Back Pressure Flow Control
Back Pressure flow control is typically used with Ethernet ports operating in half duplex mode
to send a "collision" signal to the sending port (mimicking a state of packet collision) causing the
sending port to temporarily stop sending signals and resume sending them later.
Backbone
A high-speed line or series of connections that forms a major pathway within a network.
BackOrifice
BackOrifice is a remote administration tool that allows a user to control a computer across
a TCP/IP connection using a simple console or GUI application.
Band Plan (VDSL)
Each VDSL mode operates in a different frequency range called a band plan.
Bandwidth
This is the capacity of a link usually measured in bits-per-second (bps).
Bandwidth Borrowing
A class may use bandwidth from another class if that class is not using up its current
allocation and bandwidth borrowing is allowed.
Bandwidth Class
A bandwidth class defines bandwidth allowed at an interface for an application, such as
VoIP (Voice over Internet Protocol) or FTP (File Transfer Protocol) and/or a subnetwork.
Bandwidth Control(Bandwidth Control)
Bandwidth control means defining a maximum allowable bandwidth for traffic flows from
specified source(s) to specified destination(s). See also Bandwidth Management.
Bandwidth Links
Links refers to traffic flow between the device port interfaces.
Bandwidth Management
Bandwidth management allows you to allocate bandwidth at an interface according to defined policies.
Bandwidth management lite uses firewall rules to limit bandwidth on traffic flows.
Bandwidth Monitoring
This is a graphical interface that allows you to gauge bandwidth usage.
Bandwidth Policy
A bandwidth policy is where you define what application(s) and/or subnetworks make up a bandwidth class.
Bandwidth-On-Demand
This allows you to dynamically set upstream and downstream line speeds to a particular rate of speed.
Baseband
This is a networking technology that uses a line's entire available bandwidth to transfer a single
signal of digital data. Signals are not modulated and only one kind of signal (voice or data) can be sent at a time.
Basic Encoding Rate
This is an ANSI described rule for the encoding of data units. It also refers to the ratio of bits received
that are in error. See Bit Error Rate Test.
Basic Rate Interface
This is an ISDN interface that has two B (bearer) channels that carry voice or data and one
16 Kbps D (data) channel. Also called Basic Rate Access (BRA).
Billing Profile(Billing Profile)
A billing profile is a template of predefined billing parameters such as time unit, unit cost and/or account expiration time.
Binary PKCS#7(Binary PKCS#7)
Binary PKCS#7 is a standard that defines the general syntax for data (including digital signatures) that may be encrypted.
Binary X.509(Binary X.509)
Binary X.509 is an ITU-T recommendation that defines the formats for X.509 certificates.
Bit
A Binary Digit (either a one or a zero); a single digit number in base-2. A bit is the smallest unit of computerized data.
Bit Error Rate Test
This test shows the ratio of error bits to the total number of bits transmitted. Generally
written as an exponential (10^5) to show that one out of a particular number of bits is in error.
BLES(Broadband Loop Emulation Service)
Broadband Loop Emulation Service (Voice over DSL, TR-039 Annex A) is a DSL forum standard that provides architectural requirements and recommendations for using the Loop Emulation Standard (see LES) to deploy voice services on a DSL broadband access network.
Boot Module Commands
Boot Module Commands, available in the debug mode via SMT (some devices may not have SMTs),
help you initialize the configuration of the basic functions and features of your device(s) such
as uploading firmware, changing the console port speed and viewing product-related information.
BOOTP(Bootstrap Protocol)
This is a technology that a network uses to determine its Ethernet interface's IP address.
Borrowing Priority
Borrowing priority determines which class gets to borrow bandwidth when two or more classes are vying for spare bandwidth.
Bps(Bits Per Second)
This is a standard measurement of digital transmission speeds.
Bps(Bytes Per Second)
This is a standard measurement of digital transmission speeds. One byte is eight bits.
BRA(Basic Rate Access)
This is an ISDN interface that has two B (bearer) channels that carry voice or data and
one 16 Kbps D (data) channel. Also called Basic Rate Interface.
Bridge
This is a networking device that forwards packets from one LAN to another. It uses the MAC address of an incoming packet to determine whether to drop or forward it. It allows the LANs to see each other's devices, thus it is not as private or secure as a router.
Bridge Mode(Bridge Mode)
An AP in bridge mode can function as a wireless network bridge allowing you to connect two wired network segments. The peer device also must be in bridge mode. This wireless bridge connection is equivalent to a Wireless Distribution System (WDS). See also WDS.
Bridge Priority
STP uses bridge priority to determine the root device, root port and designated port. The device with the highest priority becomes the STP root device. If all devices have the same priority, the device with the lowest MAC address will then become the root device.
Bridging
Bridging provides LAN to LAN frame forwarding services between two or more LANs. Frames from one LAN are forwarded across a bridge to a connected LAN, although filtering can be employed to selectively forward frames.
Broadband
Broadband refers to networking technologies that use modulation or multiplexing to combine multiple channels for transmission over a single medium (copper telephone wire for instance). Broadband allows you to integrate data, video and voice so that it can share one line.
Broadcast
Sending data to all computers on a network.
Broadcast Storm
A broadcast storm occurs when a packet triggers multiple responses from all hosts on a network or when
computers attempt to respond to a host that never replies. As a result, duplicated packets are continuously
created and circulated in the network, thus reducing network performance or even rendering it inoperable.
Broadcast Storm Control
Broadcast Storm Control limits the number of broadcast frames that can be stored in the switch buffer or sent out from the switch within a certain time. Broadcast frames that arrive when the buffer is full are discarded.
Brute Force Hacking
A technique used to find passwords or encryption keys. Brute Force Hacking involves trying
every possible combination of letters, numbers, etc., until the code is broken.
Brute-Force Password Guessing Protection
This is a protection mechanism to discourage brute-force password guessing attacks on the router management interfaces. Brute-force password guessing is repeatedly trying different combinations of letters, numbers and so on until the password is found. Brute-Force Password Guessing Protection enforces a wait-time after a certain number of incorrect passwords have been entered. This wait-time must expire before another password can be entered.
Byte
A set of bits that represents a single character. There are eight bits in a byte.
A Certification Authority (CA) issues certificates and guarantees the identity of each certificate owner.
Call Filtering
Call filtering is used to determine if a packet should be allowed to trigger a call. Outgoing packets
must undergo data filtering before they encounter call filtering.
Call Scheduling
Configure call time periods to restrict and allow access for users on remote nodes.
Call Waiting(Call Waiting)
Call waiting allows you to place a call on hold while you answer another incoming call on the
same telephone (directory) number.
Camping Out
Staying in a "safe" place once a hacker has broken into a system. The term can be used with
a physical location, electronic reference or an entry point for future attacks.
CAS(Channel Associated Signaling)
In telephone networks that use CAS (Channel Associated Signaling), each channel carries both
the control signal and voice signal. CAS is commonly used in America.
CBR(Constant Bit Rate)
Constant Bit Rate is an ATM service category that provides a fixed amount of bandwidth for streaming data (like voice or video). The bandwidth is always reserved, even when streaming data is not being sent.
CCS(Common Channel Signaling)
In telephone networks that use CCS (Common Channel Signaling), one channel carries the
control signal and a separate channel carries the voice signal. CCS is commonly used in Europe.
CDR(Call Detail Record)
This is a name used by telephone companies for call-related information.
Cell
This is the data packet unit that ATM transmits. One cell consists of 53 bytes.
Certificates(Certificates)
Certificates (also called digital IDs) can be used to authenticate users. Certificates are based on public-private key pairs. They provide a way to exchange public keys for use in authentication.
Certification Path(Certification Path)
A certification path is the hierarchy of certification authority certificates that validate a certificate.
Certification Request(Certification Request)
A certification request contains identifying information and public keys. You can send a certification request
to a certification authority. The certification authority signs the certification request and issues a certificate.
Channel(Channel)
A channel is a radio frequency used by a wireless device. Channels available depend on your geographical area.
CHAP(Challenge Handshake Authentication Protocol)
Challenge Handshake Authentication Protocol is an alternative protocol that avoids sending passwords over the wire by using a challenge/response technique.
Cipher Text
Text that has been scrambled or encrypted so that it cannot be read without deciphering it. See Encryption.
CIR(Committed Information Rate)
The carrier programs virtual circuits into the network between your sites and charges customers for a specific level of service called the committed information rate (CIR). The CIR is a negotiated rate and is basically a guarantee that the carrier will always have that bandwidth available.
Circuit Switched Network
This is a network that sets up a temporary physical circuit when a telephone receiver is picked up
(goes off hook) and holds the circuit open until it receives a disconnect signal.
Circuit Switching
This is the use of switches to set up a dedicated physical connection between two endpoints
until it receives a disconnect signal.
Class 5 Switch
This is a PSTN (Public Switched Telephone Network) switch in a CO.
Cleared Alarms
An administrator clears an alarm after solving its cause. When an alarm is cleared, it is
removed from the current alarm screen and becomes an historical alarm.
CLEC(Competitive Local Exchange Carrier)
A Competitive Local Exchange Carrier is a Local Exchange Carrier (LEC) that competes with the market leading or Incumbent LEC (ILEC). This type of carrier may offer Internet Access, video on demand/cable TV, long distance or local exchange service. It also includes wireless (cellular/PCS) providers.
CLI(Command Line Interface)
A command line interface is an interface in which you enter predefined commands at a command
prompt (the command line) to modify, configure and display information about a device or devices.
Client Program
A software program that is used to contact and obtain data from a server software program on another computer. Each client program is designed to work with one or more specific kinds of server programs and each server requires a specific kind of client. A web browser, for example, is a specific kind of client.
Cluster Management(Cluster Management)
Cluster management allows you to manage switches through one switch, called the cluster manager.
The switches must be directly connected and be in the same VLAN group so as to be able to communicate with one another.
Cluster Manager(Cluster Manager)
The cluster manager is the switch through which you manage the cluster member switches.
Cluster Members(Cluster Members)
The cluster members are the switches being managed by the cluster manager switch.
Clustering Candidates(Clustering Candidates)
Clustering candidates are switches that are potential cluster members.
CMP(Certificate Management Protocol)
Certificate Management Protocol (CMP) is a TCP-based certificate enrollment protocol that was developed by the Public Key Infrastructure X.509 working group of the Internet Engineering Task Force (IETF) and is specified in RFC 2510.
CO(Central Office)
A CO is a facility that serves local telephone subscribers. In the CO, subscribers' lines are joined to switching equipment that allows them to connect to each other for both local and long distance calls.
Coaxial Cable
This type of cable has a braided copper shield that surrounds a single insulated copper wire.
COE(Central Office Equipment)
COE is where home and office phone lines terminate and connect to a much larger switching system.
COM Port(Communications Port)
The communications port is used for local management of the device. In some devices,
it may also be used for uplinking.
Comfort Noise (Comfort Noise)
This is the background noise a device generates to fill moments of silence when neither party is speaking.
Community
This is the SNMP equivalent of a password.
Compression
This is a method of reducing the size of a signal.
CON/AUX Switch And Port
Set the CON/AUX switch to the "CON" side when using the CON/AUX port as a regular console port for local device configuration and management. Set this switch to the "AUX" side when using the CON/AUX port as an auxiliary dial-up WAN connection.
Console
This is a device (usually a computer) that you use to manage a networking device via a serial port (RS232) connection.
Content Filtering
Content filtering restricts or blocks access to certain web features or content from web pages.
Cookie
A string of characters saved by a web browser on the user's hard disk.
Core Network
This refers to switching offices and the transmission plants that link them together. Competing Interchange networks connect Core Networks in the US, while in other countries, the Core Networks reach to the borders of the country they are in.
Countermeasures
Techniques, programs or other tools that can protect your computer against threats.
Coverage
Coverage, or range, is the distance over which wireless devices can communicate.
CPE(Customer Premise Equipment)
CPE is privately-owned telecommunication equipment at an individual or organization's site that is
attached to the telecommunication network.
Cracker
Another term for hackers. Generally, the term cracker refers specifically to a person who maliciously
attempts to break encryption, software locks or network security.
Cracker Tools
Programs used to break into computers. Cracker tools are widely distributed on the Internet.
They include password crackers, Trojans, viruses, war-dialers and worms.
Cracking
This is the act of breaking into computers, bypassing passwords or licenses in a computer
program or intentionally breaching computer security.
CRC(Cyclic Redundancy Checking)
CRC is a method of checking for errors in data that has been transmitted on a communications link.
CRL(Certificate Revocation List)
A CRL (Certificate Revocation List) is a directory of certificates that have been revoked before their scheduled expirations.
Crossover Ethernet Cable
A cable that wires a pin to its opposite pin, for example, RX+ is wired to TX+. This cable connects two similar devices, for example, two data terminal equipment (DTE) or data communications equipment (DCE) devices.
Crosstalk
Crosstalk is noise emanating from the signals transmitted on adjacent wire pairs caused
by electric or magnetic fields of one telecommunication signal affecting the signal in an adjacent circuit.
Cryptoanalysis
The act of analyzing (or breaking into) secure documents or systems that are protected with encryption.
CSU/DSU(Channel Service Unit/Data Service Unit)
CSUs and DSUs are actually two separate devices, but they are used in conjunction and often combined into the same box. CSU/DSU are hardware devices that convert digital signals used on a LAN into a digital signal used on a WAN and vice-versa (over a T-1 line, for example).
The IPSec sender can encrypt packets before transmitting them across a network.
Data Integrity
The IPSec receiver can validate packets sent by the IPSec sender to ensure that the data has not been altered during transmission.
Data Origin Authentication
The IPSec receiver can verify the source of IPSec packets. This service depends on the data integrity service.
Daylight-Savings Time
This is a period during the late spring, summer and early fall when many countries set their clocks
ahead of normal local time by one hour to give more daylight time in the evenings.
DCE(Data Communications Equipment)
Data Communications Equipment is typically a modem or other type of communication device.
The DCE sits between the DTE (data terminal equipment) and a transmission circuit such as a phone line.
Decryption
The act of restoring an encrypted file to its original state.
Denial Of Service
Act of preventing customers, users, clients or other computers from accessing data on a computer.
This is usually accomplished by interrupting or overwhelming the computer with bad or excessive information requests.
DES(Data Encryption Standard)
Data Encryption Standard is a widely-used method of data encryption that uses a private (secret) key.DES applies a 56-bit key to each 64-bit block of data.
Device Filter Rules
Device filter rules are filter rules that treat a packet as a byte stream as opposed to an IP or IPX packet.
You specify the portion of the packet to check with the Offset (from 0) and the Length fields, both in bytes.
Device Filters
Device Filters decide whether or not to allow passage of a data packet and/or to make a call. Device
filters act on raw data from/to LAN and WAN and serve as a limited firewall to your device.
DH(Diffie-Hellman)
Diffie-Hellman is a public-key cryptography protocol that allows two parties to establish a shared secret over
an unsecured communications channel. Diffie-Hellman is used within IKE SA setup to establish session keys.
DHCP(Dynamic Host Configuration Protocol)
Dynamic Host Configuration Protocol automatically assigns IP addresses to clients when they log on.
DHCP centralizes IP address management on central computers that run the DHCP server program.
DHCP leases addresses, for a period of time, which means that past addresses are "recycled" and made
available for future reassignment to other systems.
DHCP Relay
Dynamic Host Configuration Protocol Relay is a function that allows DHCP data to be forwarded
between the computer that requests the IP address and the DHCP server.
DHCP Server
This is a device that uses DHCP (see DHCP) to assign addresses to nodes on a LAN.
Dial Backup
Dial backup is an auxiliary WAN connection that you can use if your primary WAN link goes down.
Dial Up
This is the process of setting up a connection through a switched network. It also describes a type
of Internet service where you have to connect (like a call) to your ISP for each session.
Digital
The use of a binary code to represent information, such as 0/1, or on/off.
Digital Certificate
A digital certificate is an electronic ID card that proves the sender's identity. A digital certificate
is issued by a certificate authority.
Digital Signature
Digital code that authenticates whomever signed the document or software.
DLCI(Data Link Connection Identifier)
A DLCI specifies the channel and destination that frame relay traffic will use.
DMZ(DeMilitarized Zone)
A DMZ is a network that makes public servers visible to the outside world and physically
separates them from the LAN, thus making the LAN more secure.
DNS(Domain Name System)
Domain Name System links names to IP addresses. When you access Web sites on the Internet
you can type the IP address of the site or the DNS name.
Domain Name
The unique name that identifies an Internet site. Domain Names always have two or more parts
that are separated by dots. The part on the left is the most specific and the part on the right is the most general.
Dot-Decimal Format
This is the writing out of a decimal number (base-10) using periods (dots or decimals) to separate it into parts. This is commonly used for IP addresses, such as 192.168.1.1. Also referred to as dotted-decimal notation.
Dotted-Decimal Notation
This is the writing out of a decimal number (base-10) using periods (dots or decimals) to
separate it into parts. This is commonly used for IP addresses, such as 192.168.1.1. Also
referred to as dot-decimal format.
Downlink Port
This port connects to the uplink port of another device when the devices are cascaded.
Also known as a subtending port.
DRAM(Dynamic Random Access Memory)
Dynamic RAM stores information in capacitors that must be refreshed periodically.
DSL(Digital Subscriber Line)
Digital Subscriber Line technologies enhance the data capacity of the existing twisted pair wire that runs between the local telephone company switching offices and most homes and offices.
There are actually several types of DSL service, ranging in speeds from 16 Kbits/sec to 52 Mbits/sec.
The services are either symmetrical (traffic flows at the same speed in both directions) or asymmetrical
(the downstream capacity is higher than the upstream capacity). DSL connections are point-to-point
dedicated circuits, meaning that they are always connected. There is no dial-up. There is also no switching,
which means that the line is a direct connection into the carrier's frame relay, ATM (Asynchronous Transfer
Mode) or Internet-connect system.
DSLAM(Digital Subscriber Line Access Multiplexor)
A Digital Subscriber Line Access Multiplexor (DSLAM) is a network device, usually at a telephone company central office, that receives signals from multiple customer Digital Subscriber Line connections and puts the signals on a high-speed backbone line using multiplexing techniques. Depending on the product, DSLAM multiplexers connect DSL lines with some combination of asynchronous transfer mode ATM, frame relay or IP networks.
DTE(Data Terminal Equipment)
Originally, DTE meant Dumb Terminal Equipment. But today it is a computer, bridge or router
that interconnects local area networks (LANs) in increasingly more intelligent ways.
Dual Firmware Block Structure
Devices with a "dual firmware block structure" have one "main block" and another "backup block"
You can save the current firmware into the backup block before you upload new firmware.
If the firmware in the main block gets corrupted, the device tries to boot from the backup block
automatically so the service is not interrupted.
Dynamic DNS
With Dynamic DNS support, you can have a static hostname alias for a dynamic IP address, allowing the host to be more easily accessible from various locations on the Internet. You must register for this service with a Dynamic DNS service provider to use this service.
Dynamic Link Aggregation(Link Aggregate Control Protocol )
The IEEE802.3ad standard describes Link Aggregate Control Protocol (LACP), which is a protocol that dynamically creates and manages trunk groups. When you enable LACP link aggregation on a port, the port can automatically negotiate with the ports at the remote end of a link to establish trunk groups. LACP also allows port redundancy, that is, if an operational port fails, then one of the "standby" ports becomes operational without user intervention.
EAP-TLS (Extensible Authentication Protocol -Transport Layer Security) authentication uses digital certifications for mutual authentication. The server presents a certificate to the client. After validating the identity of the server, the client sends a certificate to the server. The exchange of certificates is done in the open before a secured tunnel is created.See also EAP and EAP-TTLS.
EAP-TTLS (Extensible Authentication Protocol-Tunneled Transport Layer Service)
EAP-TTLS (Extensible Authentication Protocol-Tunneled Transport Layer Service) authentication is a type of mutual authentication where just the server sends a digital certificate to identify itself to the clients. See also EAP and EAP-TLS.
Echo Cancellation
Echo Cancellation is an attempt to cancel the delays associated with digital networks. Delays are
encountered as signals are processed through various routes within the networks, including copper wire,
fiber optic lines, microwave connections, international gateways and satellite transmissions.
Egress Port
Egress is the act of going out of something. An egress port is an outgoing port, that is, a port through
which a data packet leaves. An egress router is a router through which a data packet leaves a network
from another network.
EIR(Excess Information Rate)
This is the burst capability of the connection, for instance, the maximum allowable data transfer rate.
EMI(ElectroMagnetic Interference)
Interference by electromagnetic signals that can cause reduced data integrity and increased error rates on transmission channels.
Encapsulation
Encapsulation is the inclusion of one data structure within another structure so that the first
data structure is hidden for the time being.
Encryption
The act of substituting numbers and characters in a file so that the file is unreadable until it is
decrypted. Encryption is usually done using a mathematical formula that determines how the file is decrypted.
Encryption Algorithm
An Encryption Algorithm describes the use of encryption techniques such as DES (Data Encryption Standard) and Triple DES algorithms.
ESP(Encapsulating Security Payload)
Encapsulating Security Payload (RFC 2406) is a protocol that IPSec uses to encrypt data to ensure confidentiality.
ESS ID(Extended Service Set ID)
An Extended Service Set (ESS) is a group of access points connected to a wired LAN on the same subnet. An ESS ID uniquely identifies each group. All access points and their associated wireless stations in the same group must have the same ESSID.
Ethernet
A very common method of networking computers in a LAN. There are a number of adaptations to the IEEE 802.3 Ethernet standard, including adaptations with data rates of 10 Mbits/sec and 100 Mbits/sec over coaxial cable, twisted-pair cable and fiber-optic cable. The latest version of Ethernet, Gigabit Ethernet, has a data rate of 1 Gbit/sec.
ETSI is a non-profit organization that establishes telecommunications standards (defining coding standards and signaling schemes) for Europe. ETSI guidelines are voluntary and almost always comply with standards produced by international bodies.
ETSI Mode
This is a VDSL mode that operates in a specific frequency band allocation with associated
upstream and downstream speeds.
Events
These are network activities. Some activities are direct attacks on your system, while others
might be depending on the circumstances. Therefore, any activity, regardless of severity is
called an event. An event may or may not be a direct attack on your system.
EWC(Embedded Web Configurator)
This is an HTML-based configurator that allows easy setup and management.
FAQs list and answer the most common questions on a particular subject.
FCC(Federal Communications Commission)
The FCC (Federal Communications Commission) is in charge of allocating the electromagnetic
spectrum and thus the bandwidth of various communication systems.
Filter Rules
Filters decide whether or not to allow passage a data packet and/or make a call. There are two types of filter applications: data filtering and call filtering. Data filtering screens data to determine if the packet should be allowed to pass. Call filters prevent packets from triggering calls.
Filtering Database(Filtering Database)
The filtering database shows how frames are forwarded or filtered across a switch's ports.
The switch uses the filtering database to determine how to forward frames.
Filters
Filters tell a device whether to allow passage of a data packet and/or to make a call.
There are two types of filter applications: data filtering and call filtering.
Firewall
A hardware or software "wall" that restricts access in and out of a network. Firewalls are most often used to separate an internal LAN or WAN from the Internet.
Flash
Flashing means to press the telephone's hook for a short period of time (a few hundred milliseconds) before releasing it. On newer telephones, there should be a "flash" key (button) that generates the signal electronically.
Flash Memory
A nonvolatile storage device that can be electrically erased and reprogrammed so that data can be stored, booted and rewritten as necessary.
Flow Control
Flow control is used to manage the sending of traffic so the sending device does not transmit more than the receiving device can process. This helps prevent traffic from being dropped and having to be resent. See also IEEE802.3 Flow Control and Back Pressure Flow Control.
Fragment
These are packets less than 64 octets long, and with either CRC (Cyclic Redundant Check)
or alignment error(s).
Fragmentation Threshold(Fragmentation Threshold)
A Fragmentation Threshold is the maximum data fragment size that can be sent in a wireless network before the AP fragments the packet into smaller data frames.
Frame Relay
Frame relay is a form of packet-switching technology that routes frames of information from source to destination over a switching network owned by a carrier. Frame sizes are not fixed.
Frame Type
Each frame type is a separate logical network, even though they exist on one physical network.
Frame Types are 802.2, 802.3, Ethernet II (DIX) and SNAP (Sub-Network Access Protocol).
FTP(File Transfer Protocol)
File Transfer Protocol is an Internet file transfer service that operates on the Internet and over TCP/IP networks. A system running the FTP server accepts commands from a system running an FTP client. The service allows users to send commands to the server for uploading and downloading files.
A Single-pair High-speed Digital Subscriber Line is a symmetrical, bi-directional DSL service that operates on one twisted-pair wire. The "G." in "G.SHDSL" refers to ITU (International Telecommunication Union)
"G" tandards. G.SHDSL provides data rates from 192kbps up to 2.3 Mbps at distances of 6,000 feet to 20,000 feet on 26 AWG copper. See also DSL.
GARP(Generic Attribute Registration Protocol)
GARP allows network devices to register and de-register attribute values with other GARP participants within a bridged LAN.
Gateway
A gateway is a computer system or other device that acts as a translator between two systems that do
not use the same communication protocols, data formatting structures, languages and/or architecture.
GGP(Gateway-To-Gateway Protocol)
Gateway-to-Gateway Protocol is an Internet protocol that specifies how gateway routers communicate with each other.
Ground Start
This is a type of analog voice grade access line signaling that requires the customer interface to provide a ground on the ring conductor at the network interface to initiate service requests.
GSTN(General Switched Telephone Network) A GSTN denotes an analog network (PSTN) or digital network (ISDN).
GVRP(GARP VLAN Registration Protocol)
GVRP is a registration protocol that defines a way for 802.1Q VLAN-aware switches to register necessary VLAN members on ports across the network.
Generally, a hacker is anyone who experiments with technology - including computers and networks.
Hardware Monitor(Hardware Monitor) A device uses the hardware monitor to observe temperature, voltage and fan speed readings.
Hash
This is a type of encryption that transforms plain text input into encrypted output of a fixed length called the message digest. See also Message Digest.
HDLC(High-Level Data Link Control )
A bit-oriented (the data is monitored bit by bit), link layer protocol for the transmission of data over synchronous networks.
Hello Time
In STP, this is the time interval in seconds between configuration messages generated by the root device.
Hexadecimal Notation
Hexadecimal notation is a base-16 number as opposed to decimal (base-10) or binary (base 2).
This number representation uses 0-9 along with the letters a-f to represent the (decimal) numbers 10 to 15.
The right-most digit represents ones, the next represents multiples of 16, then 16 squared (256),
16 cubed (4096) and so on. MAC addresses are usually written in hexadecimal notation,
for example 00:a0:c5:01:23:43.
Hop Count
Hop count is a measure of distance between two points on the Internet. It is equivalent to the number of gateways that separate the source and destination.
Host
Any computer on a network that is a repository for services available to other computers on the network.
It is quite common to have one host machine provide several services, such as WWW and USENET.
Hotspot(Hotspot)
Hotspots are public areas, such as airports, hotels, coffee shops, where end users can access the Internet via a mobile device.
HTTP(Hyper Text Transfer Protocol)
The most common protocol used on the Internet. HTTP is the primary protocol used for web sites and web browsers. It is also prone to certain kinds of attacks
HTTPS(HyperText Transfer Protocol Over Secure Socket Layer)
HyperText Transfer Protocol over Secure Socket Layer, or HTTP over SSL is a web protocol that encrypts and decrypts web pages. Secure Socket Layer (SSL) is an application-level protoco l that enables secure transactions of data by ensuring confidentiality (an unauthorized party cannot read the transferred data), authentication (one party can identify the other party) and data integrity (you know if data has been changed).
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.
IBSS(Independent Basic Service Set)
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).
ICMP(Internet Control Message Protocol)
A message control and error-reporting protocol between a host server and a gateway to the Internet ICMP uses Internet Protocol (IP) datagrams, 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.
IDS(Intrusion Detection System)
An Intrusion Detection System (IDS) monitors traffic for known attack patterns and then alerts the
Network Administrator to them. The rules that define IDS attack patterns should be updated regularly.
IEEE 802.1p (IEEE 802.1p Priority)
IEEE 802.1p Priority 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(VLAN/Tagged VLANs)
802.1Q is an IEEE standard for tagged VLANs (Virtual LANs) in which a VLAN ID is inserted into the layer-2 frame header to allow the creation of dynamic VLANs across switches. Tagged VLANs are not confined to the switch on which they were created as are port-based VLANs.
IEEE 802.1x(IEEE 802.1x)
IEEE 802.1x is an extended authentication protocol that allows support of RADIUS (Remote Authentication Dial In User Service, RFC 2138, 2139) for centralized user profile management on a network RADIUS server.
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.
IGMP(Internet Group Multicast 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.
IGMP Snooping
IGMP Snooping enables a layer-2 switch to learn the members of IP Multicast groups.
Without IGMP snooping, multicast traffic is forwarded to all ports like broadcast traffic.
With IGMP snooping, group multicast traffic is only forwarded to ports that are members of that group.
IGMP Snooping generates no additional network traffic, allowing you to significantly reduce
multicast traffic passing through your switch.
IKE(Internet Key Exchange)
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.
Infrastructure(Infrastructure Network)
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
Ingress is the act of entering something. An ingress port is an incoming port, that is, the 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.
Inside Wiring
Wiring that is done from the point of demarcation to the jack in the wall where the line terminates.
Integrity
Proof that the data is the same as originally intended. Unauthorized software or people have not altered the original information.
Internal SPTGEN(Internal System Parameter Table Generator)
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.
Internet
(Upper case "I"). The vast collection of inter-connected networks that use TCP/IP protocols e
volved from the ARPANET (Advanced Research Projects Agency Network) of the late 1960's and early 1970's
Internet
(Lower case "i"). Any time you connect two or more networks together, you have an internet.
Intranet
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.
Intruder
Person or software interested in breaking computer security to access, modify, or damage data. Also see Cracker.
IP(Internet Protocol)
(Currently IP version 4 or IPv4) The underlying protocol for routing packets on the Internet and other TCP/IP-based networks.
IP Alias(Internet Protocol Alias)
Internet Protocol Alias allows you to partition a physical network into logical networks over the same Ethernet interface.
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.
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.
IP Pool(Internet Protocol Pool)
Refers to the collective group of IP addresses located in any particular place (for example, LAN,
WAN, Ethernet, etc.).
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.
IPCP (PPP)(IP Control Protocol)
Allows changes to IP parameters such as the IP address.
IPSec(Internet Protocol Security)
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.
IPX(Internetwork Packet EXchange)
The native NetWare internetworking protocol is IPX (Internetwork Packet Exchange).
Like IP (Internet Protocol), IPX is an internetworking protocol that provides datagram services.
IRC(Internet Relay Chat)
It is a way for multiple users on a system to "chat" over the network.
ISP(Internet Service Providers)
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.
ITU-T(Telecommunication Standardization Sector Of The International Telecommunications Union)
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).
These are packets that are greater than the maximum octets (specified for the system by the
configuration software) long and with either CRC or alignment error(s).
Jack Type
Different types of jacks (RJ-11, RJ45 or RJ-48) can be used for an ISDN line. The RJ-11 is the most common in the world and is most often used for analog phones, modems and fax machines. RJ-48 and RJ-45 are essentially the same, as they both have the same 8-pin configuration. An RJ-11 jack can fit into an RJ-45/RJ-48 connector, however, an RJ-45/RJ-48 cannot fit into an RJ-11 connector.
Key Management allows you to determine whether to use IKE (ISAKMP) or manual key
configuration in order to set up a VPN.
Keys
Keys are used like passwords to open and close (encrypt and decrypt) messages.
While many encryption algorithms are commonly known and public, the key must be kept secret.
The IEEE802.3ad standard describes Link Aggregate Control Protocol (LACP), which is a protocol that dynamically creates and manages trunk groups. When you enable LACP link aggregation on a port, the port can automatically negotiate with the ports at the remote end of a link to establish trunk groups. LACP also allows port redundancy, that is, if an operational port fails, then one of the "standby" ports becomes operational without user intervention.
LAN(Local Area Network)
A shared communication system to which many computers are attached. A LAN, as its name implies, is limited
to a local area. LANs have different topologies, the most common being the linear bus and the star configuration.
LATA(Local Access And Transport Area)
A geographic territory used primarily by local telephone companies to determine charges for intrastate calls.
Latency
The time it takes for a bit to be transmitted from source to destination.
LDAP(Lightweight Directory Access Protocol)
LDAP (Lightweight Directory Access Protocol) is a protocol over TCP that specifies how clients access directories of certificates and lists of revoked certificates.
LEC(Local Exchange Carrier)
The local phone companies-either a Regional Bell Operating Company (RBOC) or an independent phone
company (GTE for example)- that provide local transmission services.
LED(Light Emitting Diode)
LEDs are visual indicators that relay information about the status of specific functions to the user by lighting up, turning off or blinking. LEDs are usually found on the front panel of the physical device. Examples include Status, Power and System LEDS.
LES(Loop Emulation Standard)
Loop Emulation Standard is an ATM forum specification for sending voice traffic over ATM Adaptation Layer type 2 (AAL2).
Linux
Linux is a free, open-source UNIX-type operating system.
LLC-Multiplexing
One VC (Virtual Circuit) carries multiple protocols with protocol identifying information being contained in each packet header. Despite the extra bandwidth and processing overhead, this method my be advantageous if it is not practical to have a separate VC for each carried protocol, eg., if charging heavily depends on the number of simultaneous VCs.
Local Loopback Test
A local loopback test is used to check the device's DSL chip. A local loopback test failure indicates an internal device problem.
Logic Bomb
A virus that only activates itself when certain conditions are met. Logic bombs usually damage files
or cause other serious problems when they are activated.
Loop
A data path loop forms when there is more than one path or route between two networked devices.
Loop Start
A supervisory signal given by a telephone or PBX in response to completing the loop path.
Loop-Reach
Loop reach defines speed that can be attained at various distances. This is very important for DSL
technology as distance from the CO (Central Office) influences attainable speeds.
On a local area network (LAN) or other network, the MAC address is a computer's unique hardware number. (On an Ethernet LAN, it's the same as your Ethernet address). The MAC layer frames data for transmission over the network, then passes the frame to the physical layer interface where it is transmitted as a stream of bits.
MAC Filtering(Media Access Control Filtering)
Media Access Control filtering filters incoming frames based on MAC (Media Access Control)
address(es) that you specify.
Main Mode
Main mode is an IPSec phase 1 negotiation mode (see Negotiation Mode). Main mode ensures the highest level of security when the communicating parties are negotiating authentication (phase 1). See also Aggressive Mode.
Management VID(Management VLAN ID)
Management VLAN ID is the VLAN ID of the CPU and is used for management only.
To access the switch make sure the port that you are connected to is a member of Management VLAN.
Max Age
In STP, this is the maximum time (in seconds) a device waits without receiving a BPDU before attempting to reconfigure. STP-aware devices exchange Bridge Protocol Data Units (BPDUs) periodically. When the bridged LAN topology changes, a new spanning tree is constructed.
MD5(Message Digest 5)
Message Digest 5, HMAC-MD5 (RFC 2403) is a hash algorithm that is used to authenticate packet data. It produces a 128-bit message digest. See also Hash and SHA1.
MD5 Fingerprint(MD5 Fingerprint)
A MD5 fingerprint is a certificate's message digest that was calculated using the MD5 algorithm.
See also message digest.
MDI (Medium Dependent Interface)/MDIX (MDI crossover) is a type of Ethernet port.
MDI ports connect to MDIX ports using straight-through Ethernet cables; both MDI-to-MDI and
MDIX-to-MDIX connections use crossover Ethernet cables.
Message Digest
A message digest is the encrypted output that is the result when a hash function is performed on a plain-text message.
This fixed-length set of bits functions as a digital signature of the original message. See also Hash.
Message Digest(Message Digest)
A message digest is the fixed-length encrypted output that is the result of applying a hash to plain text input.
The message digest functions as a digital fingerprint of the original message. A message digest provides
a way to check the integrity of a message. If someone changes the original message, it produces
a different message digest.
Message Waiting(Message Waiting)
Message waiting notifies you when a voice message arrives. The details of the message waiting feature
depend on your telephone and your voice mail service.
Metering Pulse(Metering Pulse)
A metering pulse is a periodic signal that the telephone company's switch sends to a telephone during
a call in order to measure the length of the call for billing purposes.
MIB(Management Information Base )
A Management Information Base (MIB) is a collection of managed objects.
The managed devices contain object variables/managed objects that define each piece of information to be collected about a device. Examples of variables include such as the number of packets received, node port status and so on.
MIC(Message Integrity Check)
Message Integrity Check (MIC, also named Michael) is a function designed to detect if someone
has covertly altered data packets. The receiver and the transmitter each compute and compare the MIC.
If they do not match, it is assumed that the data has been tampered with and the packet is dropped.
Mirror Port
This is a port that copies the network traffic of another port for the purpose of analyzing the
network traffic. This is also known as the sniffer port or the analysis port.
Monitor Port
This is a port whose traffic is duplicated and analyzed by a sniffer port. This is also known as the source port.
MSE(Minimum Square Error )
Minimum Square Error (MSE) is the minimum mean-square error (also known as MMSE) performance
measure is a popular metric for optimal signal processing.
MTU(Multi-Tenant Units)
Buildings such as hotels, motels, resorts, residential multi-dwelling units, office buildings, university campuses, etc.
Mu-Law
Mu-Law and A-Law are Pulse Code Modulation (PCM) techniques that dictate forms of compression
for audio signals. They are widely-used standard methods of coding voice as they improve the signal-to-noise ratio without increasing the amount of data. Mu-Law is a standard in North America; A-Law in Europe.
Multi-ESS(Multiple ESS)
Multiple ESS is a function that allows multiple ESSs to be configured on just one access point.
Wireless stations can use different ESSIDs to associate with the same AP. Only wireless stations with the same ESSID can communicate with each other. This allows the AP to logically group wireless stations in a manner similar to VLAN (Virtual LAN).
Multicast
Deliver IP packets to a specific group of hosts using IP multicast. IGMP (Internet Group Management Protocol)
is the protocol used to support multicast groups.
Multiplexing
A method that combines information from multiple connections into one connection for transfer
over an ATM circuit.
Multiplexor
Multiplexors or MUXs, as they are often called, are devices that combine signals from various sources such as PBX (Private Branch Exchange), asynchronous terminals or a bridge connected to a WAN. A multiplexor transmits these signals as a single data stream over a digital line. Multiplexors conserve bandwidth.
The allocation of an IP address to a host name. See also DNS.
NAT(Network Address Translation)
The translation of an Internet Protocol address used within one network to a different IP address
known within another network - see also SUA.
NAT - Global
This refers to the packet address (source or destination) as the packet travels on the WAN.
NAT - Inside
This refers to the host on the LAN.
NAT - Local
This refers to the packet address (source or destination) as the packet travels on the LAN.
NAT -Outside
This refers to the host on the WAN.
NAT Server Set
A NAT server set is a list of inside servers (behind NAT on the LAN) that you can make visible
to the outside world.
NAT Traversal (UPnP)
UPnP NAT traversal automates the process of allowing an application to operate through NAT.
UPnP network devices can automatically configure network addressing, announce their presence
in the network to other UPnP devices and enable exchange of simple product and service descriptions.
NAT Traversal(VPN/IPSec)
NAT traversal allows IPSec tunnels using the ESP protocol to pass through NAT-enabled routers.
NDIS(Network Driver Interface Specification)
A Windows specification for how communication protocol programs (such as TCP/IP) and network
device drivers should communicate with each other.
Negotiation Mode
The phase 1 negotiation mode determines how the Security Association (SA) will be established
for each connection through IKE negotiations. See also Aggressive Mode and Main Mode.
NetBIOS(Network Basic Input/Output System)
NetBIOS is an extension of the DOS BIOS that enables a computer to connect to and communicate with a LAN.
Network
Any time you connect two or more computers together, allowing them to share resources,
you have a computer network. Connect two or more networks together and you have an internet.
Network Contention
Network contention describes a situation when two or more networked devices attempt to
use the same medium simultaneously.
NIC(Network Interface Card)
A board that provides network communication capabilities to and from a computer system. Also called an adapter.
An Operational, Administration and Maintenance Function 5 test is used to test the connection between two DSL devices. First, the DSL devices establish a virtual circuit. Then the local device sends an ATM F5 cell to be returned by the remote DSL device (both DSL devices must support ATM F5 in order to use this test).
The PAC is the box that calls/answers the phone call and relays the PPP frames to the PNS (PPTP Network Server). A PAC must have IP and dial-up capability.
Packet Filter
A filter that scans packets and decides whether to let them through or not.
PAP(Password Authentication Protocol)
A security protocol that requires users to enter a password before accessing a secure system. The user's ame
and password are sent over the wire to a server where they are compared with a database of user account names and passwords.
Passphrase
A passphrase is a string of text used for automatic WEP key generation on wireless client adapters.
Password Cracker
A program that uses a dictionary of words, phrases, names, etc. to guess a password.
Password Encryption
A system of encrypting electronic files using a single key or password. Anyone who knows
the password can decrypt the file.
Password Shadowing
The encrypted password is not visible in the password file but stored in a shadow file that is
only readable by root. This prevents brute force attacks on the encrypted field to guess the password.
Path Cost
In STP, path cost is the cost of transmitting a frame onto a LAN through that port. It is assigned
according to the speed of the link to which a port is attached. The slower the media, the higher the cost.
PBX(Private Branch Exchange)
A subscriber-owned telecommunications exchange that usually includes access to the public switched network. It may also be a private telephone switchboard that provides on-premises dial service and may provide connections to local and trunked communications networks.
PEM (Base-64) encoded PKCS#7 is a Privacy Enhanced Mail (PEM) format that uses 64 ASCII
characters to convert a binary PKCS#7 certificate into a printable form.
PEM (Base-64) encoded X.509 is a Privacy Enhanced Mail format that uses 64 ASCII characters
to convert a binary X.509 certificate into a printable form.
Penetration
Gaining access to computers or networks by bypassing security programs and passwords.
PFS(Perfect Forward Secrecy)
Perfect Forward Secrecy is an IPSec keying method that uses a brand new key for each new
IPSec SA setup. The keys are created by new key exchanges, see Diffie-Hellman.
Phreaking
Breaking into phone or other communication systems.
Ping Attack
An attack that slows down the network until it is unusable. The attacker sends a "ping" command
to the network repeatedly to slow it down. See also Denial of Service.
Pirate
Someone who steals or distributes software without paying the legitimate owner for it.
Pirated Software
Software that has been illegally copied, or that is being used in violation of the software's licensing
agreement. Pirated software is often distributed through pirate bulletin boards or on the Internet.
In the Internet underground, it is known as Warez.
PKI(Public-Key Infrastructure)
PKI (Public-Key Infrastructure) is the framework of servers, software, procedures and policies
that handles (public-key cryptography) keys.
PKIX(Public-Key Infrastructure (X.509))
Public-Key Infrastructure (X.509) refers to an IETF working group and the protocols and architecture
that it has drafted based on X.509.
Plain Text
Plain Text is clear text, readable by anyone-it is the opposite of cipher text.
PMS(Property Management System)
PMS is an automated billing system commonly used by hotels to perform in-room billing of services.
PNS(PPTP Network Server)
A PNS is the box that hosts both the PPP and the PPTP stacks and forms one end of the PPTP tunnel. The PNS must have IP connectivity.
PoE(Power Over Ethernet)
PoE is the ability to provide power to a PoE-enabled device via an 8-pin CAT 5 Ethernet cable,
eliminating the need for a nearby power source.
Point Of Demarcation
The physical point where the phone company ends its responsibility for the wiring of the phone line.
POP(Post Office Protocol)
This is a common protocol used for sending, receiving, and delivering mail messages.
Port
An Internet port refers to a number that is part of a URL, appearing after a colon (:), directly following
the domain name. Every service on an Internet server listens on a particular port number on that server.
Most services have standard port numbers, for example, Web servers normally listen on port 80.
Port (H/W)
An interface on a computer for connecting peripherals or devices to the computer. A printer port,
for example, is an interface that is designed to have a printer connected to it. Ports can be defined
by specific hardware (such as a keyboard port) or through software.
Port Bonding
This is the aggregation of separate physical DSL port links into one logical link; for example, three
SHDSL links of 2.3 Mbps can be aggregated into one logical 6.9 Mbps link.
Port Forwarding
Use this feature to forward incoming service requests to a server on your local network.
You may enter a single port number or a range of port numbers to be forwarded, and the local IP
address of the desired server.
Port Mirroring
Port mirroring allows you to copy traffic from one port to another port in order to examine the first
port's raffic without interfering with it.
Port Security(Port Security)
Port security allows only packets with dynamically learned MAC addresses and/or configured static
MAC addresses to pass through a port on the switch.
Port Trunking
This is the aggregation of separate physical port links into one logical link; for example, two fast
Ethernet links can be aggregated into one logical 200 Mbps link.
Port-Based VLAN
Port-based VLANs are VLANs where the packet forwarding decision is based on the destination
MAC address and its associated port. Port-based VLANs are specific only to the device on
which they were created.
Portal Page(Portal Page)
A portal page is the first web site to which a subscriber is directed after logging in successfully.
POTS(Plain Old Telephone Service)
The analog telephone service that runs over copper twisted-pair wires and is based on the original
Bell telephone system. Twisted-pair wires connect homes and businesses to a neighborhood central
office. This is called the local loop. The central office is connected to other central offices
and long-distance facilities.
PPP(Point-To-Point Protocol)
PPP encapsulates and transmits IP (Internet Protocol) datagrams over serial point-to-point links.
The protocol is defined in IETF (Internet Engineering Task Force) RFC 1661 through 1663.
PPP provides router-to-router, host-to-router, and host-to-host connections.
PPPoA(Point-To-Point-Protocol Over ATM.)
One of the two types of PPP interfaces you can define for a Virtual Circuit(VC), the other being PPPoE.
You can only define one PPPoA per VC.
PPPoE(Point-To-Point Protocol Over Ethernet)
PPPoE relies on two widely accepted standards: PPP and Ethernet. PPPoE is a specification for
connecting the users on an Ethernet to the Internet through a common broadband medium, such
as a single DSL line, wireless device or cable modem.
PPTP(Point-To-Point Tunneling Protocol)
Point-to-Point Tunneling Protocol (PPTP) is a network protocol that enables secure transfer of data
from a remote client to a private server, creating a Virtual Private Network (VPN) using a TCP/IP-based
network.
Pre-Shared Key
A pre-shared key identifies a communicating party during a phase 1 IKE negotiation. It is called "pre-shared"
because you have to share it with another party before you can communicate with them over
a secure connection.
Promiscuous Packet Capture
Actively capturing packet information from a network. Most computers only collect packets specifically
addressed to them. Promiscuous packet capture acquires all network traffic it can regardless of where
the packets are addressed.
Protocol
A "Lnguage" or communicating on a network. Protocols are sets of standards or rules used to define,
format and transmit data across a network. There are many different protocols used on networks.
For example, most web pages are transmitted using the HTTP protocol.
Protocol Filters
Use Protocol Filters to decide whether or not to allow passage of a data packet and/or to make a call.
Protocol filters act on IP/IPX packets and can serve as a limited firewall.
Proxy Server
A server that performs network operations in lieu of other systems on the network. Proxy Servers
are most often used as part of a firewall to mask the identity of users inside a corporate network
yet still provide access to the Internet.
PSTN(Public Switched Telephone Network)
Public Switched Telephone Network was put into place many years ago as a voice telephone
call-switching system. The system transmits voice calls as analog signals across copper twisted cables
from homes and businesses to neighborhood COs (central offices); this is often called the local loop.
The PSTN is a circuit-switched system, meaning that an end-to-end private circuit is established
between caller and the person called.
PTT
PTT is a generic European name that usually refers to state-owned telephone companies.
Public Key Encryption
System of encrypting electronic files using a key pair. The key pair contains a public key used during
encryption, and a corresponding private key used during decryption.
PVC(Permanent Virtual Circuit)
A PVC is a logical point-to-point circuit between customer sites. PVCs are low-delay circuits because
routing decisions do not need to be made along the way. Permanent means that the circuit is preprogrammed
by the carrier as a path through the network. It does not need to be set up or torn down for each session.
Quality of Service refers to both a network's ability to deliver data with minimum delay, and the networking
methods used to provide bandwidth for real-time multimedia applications.
Queuing Algorithms(Queuing Algorithms)
Queuing algorithms allow devices to maintain separate queues for packets from each individual source
or flow and prevent a source from monopolizing the bandwidth.
RADIUS(Remote Authentication Dial-In User Service)
A RADIUS (Remote Authentication Dial-In User Service)(RFC2138, 2139) server performs authentication,
authorization and accounting for a network.
Rate Adaption
Rate adaption is the ability of the device to adjust the configured transmission rate to the attainable
transmission rate automatically depending on your telephone line quality.
RBOC(Regional Bell Operating Company)
There are currently seven regional telephone companies that were created by the AT&T divestiture.
Reconnaissance
The finding and observation of potential targets for a cracker to attack.
Remote Loopback Test
A remote loopback test is used to test the connection between two DSL devices. The local device
sends an Ethernet frame to the other (remote) DSL device and checks for it to be returned.
Replay Detection
The IPSec receiver can detect and reject old or duplicate packets to protect against replay attacks.
Reset Button
This hardware button is used to restore the factory default settings.
Reverse Engineering
Reverse engineering means analyzing software, firmware, or hardware to find out how it works.
RFC(Request For Comments)
An RFC is an Internet formal document or standard that is the result of committee drafting and
subsequent review by interested parties.
Ring Type
Ring Type determines the sound and frequency of your telephone's ring.
RIP(Routing Information Protocol)
An interior or intra-domain routing protocol that uses distance-vector routing algorithms.
RIP is used on the Internet and is common in the NetWare environment as a method for exchanging
routing information between routers.
Roaming
Roaming in wireless network applications is a wireless feature that allows wireless LAN clients to connect
through multiple access points while moving from coverage area to coverage area.
Root Bridge
In STP, the root bridge is the base of the spanning tree; it is the bridge with the lowest identifier value (MAC address).
Router
A device that connects two networks together. Routers monitor, direct and filter information that passes
between these networks.
RS-232
RS-232 is an EIA standard which is the most common way of linking data devices together.
RSA(RSA)
RSA is a public-key encryption and digital signature algorithm.
Rx CRC
This is the number of frames received on this interface with CRC (Cyclic Redundant Check) error(s).
Rx KB/S
This is the number of kilobytes per-second received on an interface.
Define the length of time before an IKE Security Association automatically renegotiates in this field.
It may range from 300 seconds (five minutes) to 86,400 seconds (one day).
SAP(Service Advertising Protocol)
In NetWare, the SAP broadcasts information about available services on the network that other
network devices can listen to. A server sends out SAP messages every 60 seconds. A server also
sends out SAP messages to inform other devices that it is closing down. Workstations use SAP to
find services they need on the network.
SATAN(System Administrator's Tool For Analyzing Networks)
A UNIX program that gathers information on networks and stores it in databases. It is helpful in finding security flaws such as incorrect settings, software bugs and poor policy decisions.
It shows network services that are running, the different types of hardware and software on the network, and other information.
SCEP(Simple Certificate Enrollment Protocol)
Simple Certificate Enrollment Protocol (SCEP) is a TCP-based certificate enrollment protocol
that was developed by VeriSign and Cisco.
SDSL(Symmetrical Digital Subscriber Line)
A Symmetrical Digital Subscriber Line is a symmetrical, bi-directional DSL service that operates
on one twisted-pair wire. It can provide data rates up to the T1 rate of 1.544 Mbits/sec, and it
operates above the voice frequency, so voice and data can be carried on the same wire.
Secure Gateway IP Address
Secure Gateway IP Address is the WAN IP address of the remote IPSec router.
Self-Signed Certificate(Self-Signed Certificate)
A self-signed certificate is one that you generate on a device. The device acts as the certification
authority and signs the certificate itself.
Server
A computer, or a software package, that provides a specific kind of service to client software
running on other computers.
SHA1(Secure Hash Algorithm)
Secure Hash Algorithm HMAC-SHA-1 (RFC 2404) is a hash algorithm that is used to authenticate
packet data. It produces a 160-bit message digest. See also Hash and MD5.
SHA1 Fingerprint(SHA1 Fingerprint)
A SHA1 fingerprint is a certificate's message digest that was calculated using the SHA1 algorithm.
See also message digest.
Shoulder Surfing
Looking over someone's shoulder to see the numbers they dial on a phone, or the information they
enter into a computer.
SMT(System Management Terminal)
The SMT is a menu-based interface that you use to configure your device.
SNMP(Simple Network Management Protocol )
SNMP is a popular management protocol defined by the Internet community for TCP/IP networks.
It is a communication protocol for collecting information from devices on the network.
Snooping
Passively watching a network for information that could be used to a hacker's advantage,
such as passwords. Usually done while Camping Out.
SNR
Signal-to-Noise Ratio (SNR) is the ratio of the amplitude of the desired (DSL) signal to the amplitude
of noise signals at a given point in time. The higher the SNR number, the better the line quality.
Socks
A protocol that handles TCP traffic through proxy servers.
SPAM
Unwanted e-mail, usually in the form of advertisements.
Spanning Tree Algorithm
The spanning-tree algorithm calculates the best loop-free path throughout a switched network.
SPI(Security Parameter Index)
An SPI is used to distinguish different SAs terminating at the same destination and using the same
IPSec protocol. This data allows for the multiplexing of SAs to a single gateway. The SPI
(Security Parameter Index) along with a destination IP address uniquely identify a
particular Security Association (SA).
Splitter
In telephony, a splitter, sometimes called a "plain old telephone service splitter" is a device that
divides a telephone signal into two or more signals, each carrying a selected frequency range, and
can also reassemble signals from multiple signal sources into a single signal.
Spoofing
To forge something, such as an IP address. IP spoofing is a common way for hackers to hide their location and identity.
SPQ(Strict Priority Queuing)
Strict Priority Queuing (SPQ) services queues based on priority only. As traffic comes into the switch,
traffic on the highest priority queue is transmitted first. When that queue empties, traffic on the next
highest-priority queue is transmitted until that queue empties, and so on. If higher priority queues never empty,
then traffic on lower priority queues never gets sent. See also Queuing Algorithms.
SSH(Secure Shell)
SSH is a secure communication protocol that combines authentication and data encryption to provide
secure encrypted communication between two hosts over an unsecured network.
SSL(Secured Socket Layer)
Statement Printer(Statement Printer). See account generator printer.
Static MAC Address Forwarding(Static MAC Address Forwarding)
A static MAC address entry is an address that you manually enter into the MAC address-learning table.
Static MAC addresses do not age out. This may reduce unicast flooding. The devices with MAC
addresses on this list cannot receive traffic on another port on the device.
Static Routing
Static routes tell routing information that a networking device cannot learn automatically through
other means. The need for static routing can arise in cases where RIP is disabled on the LAN
or a remote network is beyond the one that is directly connected to a remote node.
STP(Shielded Twisted-Pair)
STP cable consists of copper-core wires surrounded by an insulator. Two wires are twisted
together to form a pair; the pair form a balanced circuit. The twisting prevents interference
problems, STP provides protection against external crosstalk.
STP(Spanning Tree Protocol)
STP detects and breaks network loops and provides backup links between switches, bridges
or routers. It allows a device to interact with other STP-aware devices in your network to ensure
that only one path exists between any two stations on the network.
Straight-Through Ethernet Cable
A cable that wires a pin to its equivalent pin. This cable connects two dissimilar devices, for example,
a data terminal equipment (DTE) device and a data communications equipment (DCE) device.
A straight-through Ethernet cable is the most commonly used Ethernet cable.
SUA(Single User Account)
Your system's SUA feature allows multiple user Internet access for the cost of a single ISP account.
Subnet Mask
The subnet mask specifies the network number portion of an IP address. Your device will compute the
subnet mask automatically based on the IP Address that you entered. You do not need to change the
computer subnet mask unless you are instructed to do so.
Subnetting
With subnetting, the class arrangement of an IP address is ignored. For example, a class C address no
longer has to have 24 bits of network number and 8 bits of host ID. With subnetting, some of the
host ID bits are converted into network number bits.
Switch
A layer-2 network device that selects a path or circuit to send a data packet through.
Syslog(System Log)
An abbreviated form of System Log. Using the UNIX syslog facility, a device records (logs) phone
calls or creates a CDR (Call Detail Record). Syslog is an administrative tool that assists in accounting
and is configurable via the SMT.
A T1 line consists of 24 voice channels packed into a 193 bit frame and transmitted at 1.544 Mbps.
The unframed version, or payload, is 192 bits at a rate of 1.536 Mbps.
Tagged VLAN(IEEE 802.1Q VLAN)
802.1Q is an IEEE standard for tagged VLANs (Virtual LANs) in which a VLAN ID is inserted into
the layer-2 frame header to allow the creation of dynamic VLANs across switches. Tagged VLANs
are not confined to the switch on which they were created as are port-based VLANs.
TCP(Transmission Control Protocol)
TCP is a connection-oriented transport service that ensures the reliability of message delivery.
It verifies that messages and data were received.
TCP/IP Filter Rules
TCP/IP filter rules allow you to base the rule on the fields in the IP and the upper layer protocol,
for example, UDP and TCP headers.
Telco
The generic name for telephone companies throughout the world.
Telnet
Telnet is the login and terminal emulation protocol common on the Internet and in UNIX environments.
It operates over TCP/IP networks. Its primary function is to allow users to log into remote host systems.
TEMPEST(Telecommunications Electronics Material Protected From Emanating Spurious Transmissions)
Electromagnetic signals radiate from electronic equipment and cables. Extra shielding is used on cables
and equipment to meet TEMPEST requirements, in order to stop these signals from going out to unauthorized listeners.
Terminal
A device that allows you to send commands to a computer somewhere else. At a minimum, this usually
means a keyboard, display screen and some simple circuitry.
Terminal Software
Software that pretends to be (emulates) a physical terminal and allows you to type commands to a
computer somewhere else.
TFTP(Trivial File Transfer Protocol)
TFTP is an Internet file transfer protocol similar to FTP (File Transfer Protocol), but it is scaled
back in functionality so that it requires fewer resources to run. TFTP uses the UDP (User Datagram Protocol)
rather than TCP(Transmission Control Protocol).
Three Way Calling(Three Way Calling)
Three way calling allows you to add a third party to an existing call. You must subscribe to your
telephone company for this service.
A twisted pair telephone wire consists of one tip wire and one ring wire. The polarity on the tip and ring
wires gets reversed according to the requirements of a country's telephone system.
TKIP(Temporal Key Integrity Protocol)
Temporal Key Integrity Protocol (TKIP) is an encryption protocol that uses 128-bit keys that
are dynamically generated and distributed by the authentication server. TKIP regularly changes
and rotates the encryption keys so that the same encryption key is never used twice.
Traffic Redirect
Traffic Redirect forwards WAN traffic to a backup gateway on the LAN when the router cannot
connect to the Internet, thus acting as an auxiliary backup.
Transport
IPSec uses transport mode to protect upper layer protocols and affects only the data in the IP packet.
The IP packet contains the security protocol (AH or ESP) located after the original IP header and options,
but before any upper layer protocols contained in the packet (such as TCP and UDP).
Trap
A trap is a report sent to an SNMP manager when an event occurs.
Trigger Port Forwarding
Trigger Port Forwarding allows computers on your LAN to dynamically take turns communicating
with servers on the WAN that do not accept NAT port translation.
Triple DES
This is a stronger variant of DES (Data Encryption Standard). Triple DES is a widely-used method
of data encryption that applies three separate private (secret) 56-bit keys to each 64-bit block of data.
Trojan, Trojan Horse
Like the fabled gift to the residents of Troy, a Trojan Horse is an application designed to look harmless.
Yet, when you run the program it installs a virus or memory resident application that can steal passwords,
corrupt data or provide hackers a back door into your computer. Trojan applications are particularly
dangerous since they can often run exactly as expected without showing any visible signs of intrusion.
Trunking
Trunking (link aggregation) is the grouping of physical ports into one logical higher-capacity link.
You may want to trunk ports of for example, if it is cheaper to use multiple lower-speed links than to
under-utilize a higher-speed, but more costly, port link. However, the more ports you aggregate to
get higher bandwidth then the fewer available ports you have.
Tunnel
IPSec uses tunnel mode to encapsulate the entire IP packet and transmit it securely. Tunnel mode is
fundamentally an IP tunnel with authentication and encryption and is required for gateway services to
provide access to internal systems.
Twisted Pair
Two insulated wires, usually copper, twisted together and often bound into a common sheath to
form multi-pair cables. In ISDN, the cables are the basic path between a subscriber's terminal or telephone
and the PBX or the central office.
Tx KB/S
This is the number of kilobytes per-second transmitted on an interface.
Unspecified Bit Rate is an ATM service category that does not appropriate fixed bandwidth or guarantee
throughput and is best used for non-time-critical applications, such as e-mail.
UDP(User Datagram Protocol)
UDP is a connectionless transport service that dispenses with the reliability services provided by TCP.
UDP gives applications a direct interface with the Internet Protocol (IP) and the ability to address
a particular application process running on a host via a port number without setting up a connection session.
UID(User IDentification)
User IDentification is equivalent to your user name. Usually a password is associated with a UID or user name.
UNI
User Network Interface defines the connection between user equipment and the Frame Relay network
, for instance, if your device is connected to a service provider.
UNIX(UNiplexed Information And Computer System)
A widely-used operating system in large networks. Usually used on workstations and servers.
Uplink Port
This port connects to an external switching hub, router or server.
UPnP(Universal Plug And Play)
Universal Plug and Play (UPnP) is a distributed, open networking standard that uses TCP/IP for
simple peer-to-peer network connectivity between devices. A UPnP-enabled device can dynamically
join a network, obtain an IP address, convey its capabilities and learn about other devices on the network.
URL(Uniform Resource Locator)
URL is an object on the Internet or an intranet that resides on a host system. Objects include directories
and an assortment of file types, including text files, graphics, video and audio. A URL is the address
of an object that is normally typed in the Address field of a Web browser. A URL is basically a pointer
to the location of an object.
UTC(Universal Coordinated Time)
Universal Coordinated Time is a standard time for use around the world. UTC was formerly known as
Greenwich Mean Time (GMT) and reflects the mean solar time along the prime meridian (0 longitude)
that runs through the Greenwich Observatory outside of London, where the system originated.
V.35 is a standard transfer rate implemented under recommendations by the ITU-TS (Telecommunication
Standardization Sector of the International Telecommunications Union). V.35 provides the trunk interface
between a network access device and a packet network with data rates greater than 19.2 Kbps. V.35
may use the bandwidths of several telephone circuits as a group. See also, V Series Recommendations.
VAD(Voice Activity Detection)
Voice Activity Detection (or silence suppression) allows a device to only transmit sound when it detects it.
VBR-Rt(Variable Bit Rate Real Time)
Variable Bit Rate Real Time is an ATM service category that provides a fixed amount of bandwidth
for high priority, but only when it is being sent. VBR-rt is best used for on-and-off (bursty) traffic.
VC(Virtual Circuit)
A series of virtual paths between circuit end points. This is a logical link that behaves like a dedicated
point-to-point line.
VC-Based Multiplexing
By prior mutual agreement, each protocol is assigned to a specific virtual circuit, eg., VCI carries IP,
VC2 carries IPX, etc. VC-based multiplexing may be dominant in environments where dynamic creation
of large numbers of ATM VCs is fast and economical.
VCI(Virtual Channel Identifier)
A VCI is a number that denotes a particular logical connection between end stations (users or networks).
A VCI specifies the channel and destination that ATM traffic will use. See also, VPI.zz
VDSL(Very High Bit Rate DSL )
Very High Bit Rate DSL is an asymmetric version of DSL that is used as the final drop from a fiber
optic junction point to nearby customers. VDSL lets an apartment or office complex obtain high-bandwidth
services using existing copper wires without having to replace the infrastructure with optical fiber. Like
ADSL, VDSL can share the line with the telephone.
VID(VLAN Identification)
VID is the unique VLAN identification number.
Virtual Channel
A logical connection between ATM switches.
Virtual Path
A bundle of virtual channels.
VLAN(Virtual Local Area Network)
A VLAN allows a physical network to be partitioned into multiple logical networks. Only stations within the same group can communicate with each other. Stations on a logical network can belong to one or more groups.
VLAN Trunking(Virtual LAN Trunking)
VLAN trunking on a port allows traffic belonging to unknown VLAN groups to pass through that port. This is useful if you want to set up VLAN groups on end devices without having to configure the same VLAN groups on intermediary devices.
VMoA(Voice And Multimedia Over ATM)
Voice and Multimedia over ATM is an ATM forum standard for sending voice and multimedia
signals across a network as ATM cells. The voice and multimedia signals are carried over AAL-2.
VoATM(Voice Over ATM)
Voice over ATM is an ATM forum standard for sending a voice signal across a network as
ATM cells. The voice signal is carried over AAL-2.
VoDSL(Voice Over Digital Subscriber Line)
Voice over Digital Subscriber Line is the sending of a voice signal across a network as ATM cells.
The voice signal is carried over AAL-2. This allows the combination of multiple voice/fax/modem
lines and Internet access (data) on a single DSL line. The data signal is carried over AAL-5.
Voice Gateway
A voice gateway is an interface to the telephone network for VoDSL services found between an
AAL-2 circuit and a GSTN.
VoIP(Voice Over Internet Protocol)
Voice over Internet Protocol is the converting of the voice signal to data (IP) packets and then sending
the packets over an IP network.
VPI(Virtual Path Identifier)
A VPI is a number that denotes a bundle of virtual channels. A VPI specifies the path and destination
that ATM traffic will use. See also, VCI.
VPN(Virtual Private Network)
These networks use public connections (such as the Internet) to transfer information. That information is
usually encrypted for security purposes.
This is a list of web site address(es) which all users can access without logging in.
WAN(Wide Area Networks)
WANs link geographically dispersed offices in other cities or around the globe including switched
and permanent telephone circuits, terrestrial radio systems and satellite systems.
War Dialer
A program that automatically dials phone numbers looking for computers on the other end.
They catalog numbers so that hackers can call back and try to break in.
Warez
A term that describes pirated software on the Internet.
WDS(Wireless Distribution System)
A Distribution System (DS) is a wired connection between two or more APs, while a WDS is a wireless connection. An AP using WDS can function as a wireless network bridge allowing you to wirelessly connect two wired network segments.
WEP(Wired Equivalent Privacy)
WEP (Wired Equivalent Privacy) encrypts data transmitted between wired and wireless networks
to keep the transmission private.
WFQ(Weighted Fair Queuing)
Weighted Fair Queuing (WFQ) services queues based on their priority and queue weight.
Queues with larger weights get more service than queues with smaller weights. This queuing mechanism
is highly efficient in that it divides any available bandwidth across the different traffic queues.
See also Queuing Algorithms.
Wire Tapping
Connecting to a network and monitoring all traffic. Most wire tapping features can only monitor the
traffic on their subnet.
A wireless client supplicant is the software that runs on an operating system instructing the wireless
client how to use WPA.
Worm
A program that seeks access into other computers. Once a worm penetrates another computer it
continues seeking access to other areas. Worms are often equipped with dictionary-based password
crackers and other cracker tools that enable them to penetrate more systems. Worms often steal
or vandalize computer data.
WPA(Wi-Fi Protected Access)
Wi-Fi Protected Access (WPA) is a subset of the IEEE 802.11i security specification draft.
WPA applies IEEE 802.1x and Extensible Authentication Protocol (EAP) to authenticate wireless
clients using an external RADIUS database. WPA encrypts data by using Temporal Key Integrity
Protocol (TKIP), Message Integrity Check (MIC) and IEEE 802.1x. See also WPA-PSK
(WPA -Pre-Shared Key).
WPA-PSK (WPA -Pre-Shared Key)
WPA-PSK (WPA -Pre-Shared Key) requires a single (identical) password entered into each
access point, wireless gateway and wireless client. As long as the passwords match, a client will be
granted access to a WLAN. See also WPA.
