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Vantage Access

Vantage Access is a web-based management tool that allows you to remotely manage, control and monitor multiple compatible devices. A compatible device is any device that supports the TR-069, TR-098, TR-104 or TR-106 protocols.


Varifocal Lens

Many so-called “zoom” lenses, particularly in the case of fixed lens cameras, are actually varifocal lenses, which gives lens designers more flexibility in optical design trade-offs (focal length range, maximum aperture, size, weight, cost) than true parfocal zoom, and which is practical because of auto-focus, and because the camera processor can move the lens to compensate for the change in the position of the focal plane while changing magnification (“zooming”), making operation essentially the same as a true parfocal zoom.



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.



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.



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.



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.



A tone is a sub-channel of a VDSL band. DMT divides VDSL bands into many 4.3125 kHz tones.



VDSL2 (Very High Speed Digital Subscriber Line 2) is the second generation of the VDSL standard (which is currently denoted VDSL1). VDSL2 allows a frequency band of up to 30MHz and transmission rates of up to 100Mbps in each direction. VDSL2 is defined in G.993.2. See also VDSL.


VDSL2 profile (Frequency Plan)

Eight VDSL2 frequency profiles (8a, 8b, 8c, 8d, 12a, 12b, 17a, and 30a) are defined in G.993.2. Each profile covers certain settings and parameters, such as maximum aggregate transmit power. The higher-frequency profiles (17a and 30a) are mostly used to deliver high speed at shorter distances.



VID is the unique VLAN identification number.


Virtual Channel

A logical connection between ATM switches.


Virtual Path

A bundle of virtual channels.


Virtual address mapping (NAT over IPSec)

Virtual address mapping (NAT over IPSec) changes the source IP addresses of packets from local devices to logical IP addresses before sending them through the VPN tunnel. Virtual address mapping allows local and remote networks to have overlapping IP addresses.


Virtual Router

In VRRP, a virtual router (VR) represents a number of physical layer-3 devices.


Virtual Link

In OSPF, a virtual link establishes/maintains connectivity between a non-backbone area and the backbone.


Virtual Noise

If there is too much noise on a line, the allowed line speed may be reduced or the line may not initialize. Virtual noise is the noise allowed on the line before the first line speed adjustment occurs.


Virtual AP (Access Point)

A physical AP may be able to support several logical independent wireless networks called virtual APs. A virtual AP (Access Point) can offer multiple wireless network services to wireless clients, but it must be supported by a physical AP. Mutiple virtual APs supported by the same physical AP have independent SSIDs and security modes. Virtual APs use the same channel as the physical AP which conserves channels and reduces the possibility of WLAN channel interference.



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 Isolation

This feature blocks users in a VLAN from sending traffic directly to each other.


VLAN Mapping

With VLAN mapping enabled, a switch can translate the VLAN ID and priority level of packets received from a private network to those used in the service provider’s network.


VLAN Stacking

VLAN stacking allows a service provider to distinguish multiple subscriber VLANs, even those with the same (subscriber-assigned) VLAN ID, within its network.


VLAN Translation

With VLAN translation, a switch can map the VLAN ID and priority level of packets received from a private network to those used in the service provider’s network, or add a VLAN ID and priority level to untagged packets.


VLAN 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.



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.



Virtual Network Computing (VNC) allows you to view a computer’s ‘desktop’ environment through the Internet. It uses TCP port 5900 by default.



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.



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.


Voice Re-injection

Voice re-injection allows you to make VoIP calls from any of your home’s telephones that are on the same line as the VoIP device. You may still make calls to PSTN telephone numbers via the VoIP network.



Voice over Internet Protocol (VoIP) allows you to make phone calls and send faxes over the Internet at a fraction of the cost of using the traditional telephone network.


VoIP Trunking

This is the ability of some devices to serve as a gateway between the Public Switched Telephone Network (PSTN) and Voice over Internet Protocol (VoIP) network. A PSTN caller can call into a VoIP trunking device and forward calls over the Internet or a VoIP call can be forwarded to a PSTN phone.


Volatile memory

Volatile memory (such as DRAM and SRAM) requires a continuous power supply in order to maintain data storage.



A volume is a logical area on a device that allows data to be written and read. It is typically represented in your computer’s operating system as a drive with a letter and can be sub-divided into files and folders. For example, on a typical home computer the logical volume that exists on the hard drive that hosts the Windows operating system is most often labeled the “C” drive. A device can contain a single logical volume or it can be partioned into multiple logical volumes. Futhermore, with the assistance of a logical volume manager, a logical volume can span multiple devices.


Volume Manager

A volume manager is a tool that gives system administrators greater flexibility in setting up and managing their system’s storage allocation. With it, an administrator can create, delete, move and resize any number of logical volumes.



Voice over Wireless Local Area Network (VoWLAN) is the use of VoIP over a wireless network.



In VoIP, the Voice Packetization Interval (VPI) sets the amount of audio information contained in each packet of data transmitted. 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.


VPN Concentrator

A VPN concentrator combines several IPSec VPN connections into one secure network. This reduces the number of VPN connections that must be set up and maintained in order to connect multiple locations.


VPN High Availability

See IPSec High Availability.


VPN Pass Through

VPN pass through allows a router to route encrypted traffic.



Virtual Routing Redundancy Protocol, defined in RFC 2338, allows you to create redundant backup gateways to ensure that the default gateway of a host is always available.



Vendor Specific Attributes (VSAs), as defined in RFC 2865, are configuration data sent between a RADIUS server and a network access device (for example, an Ethernet switch). A company can create VSAs to increase the functionality of a RADIUS server. For example, VSAs can be used to change bandwidth management settings on a network switch. See RADIUS.



VTP (VLAN Trunking Protocol) allows all customer switches to use consistent VLAN configuration through the service provider’s network.