V.24
- ITU-T standard for a physical layer
interface between DTE and DCE. V.24 is essentially the same as the
EIA/TIA-232 standard. See also EIA/TIA-232.
- ITU-T specification describing
procedures for call setup and tear down over the DTE-DCE interface
in a PSDN.
- ITU-T standard serial line protocol
for bidirectional data transmissions at speeds of 4.8 or 9.6 Kbps.
See also V.32bis.
- ITU-T standard that extends V.32 to
speeds up to 14.4 Kbps. See also V.32.
V.34
- ITU-T standard that specifies a serial
line protocol. V.34 offers improvements to the V.32 standard,
including higher transmission rates (28.8 Kbps) and enhanced data
compression. Compare with V.32.
V.35
- ITU-T standard describing a
synchronous, physical layer protocol used for communications between
a network access device and a packet network. V.35 is most commonly
used in the United States and in Europe, and is recommended for
speeds up to 48 Kbps.
- ITU-T standard protocol for error
correction using LAPM. See also LAPM.
variable bit rate
- See VBR.
variable-length subnet mask
- See VLSM.
- Variable bit rate.
QOS class defined by the ATM Forum for ATM networks. VBR is
subdivided into a real time (RT) class and non-real time (NRT)
class. VBR (RT) is used for connections in which there is a fixed
timing relationship between samples. VBR (NRT) is used for
connections in which there is no fixed timing relationship between
samples, but that still need a guaranteed QOS. Compare with ABR
(available bit rate), CBR,
and UBR.
VC
- See virtual
circuit.
- Virtual channel connection.
Logical circuit, made up of VCLs, that carries data between two end
points in an ATM network. Sometimes called a virtual circuit
connection. See also VCI,
VCL,
and VPI.
- Virtual channel identifier.
16-bit field in the header of an ATM cell. The VCI, together with
the VPI, is used to identify the next destination of a cell as it
passes through a series of ATM switches on its way to its
destination. ATM switches use the VPI/VCI fields to identify the
next network VCL that a cell needs to transit on its way to its
final destination. The function of the VCI is similar to that of the
DLCI in Frame Relay. Compare to DLCI.
See also VCL
and VPI.
- Virtual channel link.
Connection between two ATM devices. A VCC is made up of one or more
VCLs. See also VCC.
- Virtual circuit number.
12-bit field in an X.25 PLP header that identifies an X.25 virtual
circuit. Allows DCE to determine how to route a packet through the
X.25 network. Sometimes called LCI (logical channel identifier) or
LCN (logical channel number).
vector
- Data segment of an SNA message. A
vector consists of a length field, a key that describes the vector
type, and vector-specific data.
VERS
- Version number field with in an IP
datagram
.
Versatile Interface Processor
- See VIP.
- Backbone cabling. See backbone
cabling.
- Virtual Integrated Network
Service. NOS developed and marketed by Banyan Systems.
- 1.) Versatile Interface
Processor. Interface card used in Cisco 7000 and Cisco 7500
series routers. The VIP provides multilayer switching and runs the
Cisco IOS software. See also Cisco
7000 and Cisco
7500.
2.) Virtual IP. Function that enables the creation of logically separated switched IP workgroups across the switch ports of a Catalyst 5000 running Virtual Networking Services software. See also Virtual Networking Services.
virtual address
- See network
address.
virtual channel
- See virtual
circuit.
virtual channel connection
- See VCC.
virtual channel identifier
- See VCI.
virtual channel link
- See VCL.
- Logical circuit created to ensure
reliable communication between two network devices. A virtual
circuit is defined by a VPI/VCI pair, and can be either permanent (a
PVC) or switched (an SVC). Virtual circuits are used in Frame Relay
and X.25. In ATM, a virtual circuit is called a virtual channel.
Sometimes abbreviated VC. See also PVC,
SVC,
VCI,
virtual
route, and VPI.
virtual circuit connection
- See VCC.
virtual circuit number
- See VCN.
Virtual Integrated Network Service
- See VINES.
virtual IP
- See VIP.
virtualization
- Process of implementing a network
based on virtual network segments. Devices are connected to virtual
segments independent of their physical location and their physical
connection to the network.
virtual LAN
- See VLAN.
virtual LAN internetwork
- See VLI.
- Software on some Catalyst 5000
switches that enables multiple workgroups to be defined across
switches and offers traffic segmentation and access control.
- Logical grouping of virtual circuits
that connect two sites. See also virtual
circuit.
virtual path connection
- See VPC.
virtual path identifier
- See VPI.
virtual path identifier/virtual
channel identifier
- See VPI/VCI.
virtual path link
- See VPL.
virtual ring
- Entity in an SRB network that
logically connects two or more physical rings together either
locally or remotely. The concept of virtual rings can be expanded
across router boundaries.
- In SNA, a logical connection between
subarea nodes that is physically realized as a particular explicit
route. SNA terminology for virtual circuit. See also virtual
circuit.
VirtualStream virtual workgroups
- Cisco workgroup architecture
implemented on the LightStream 2020 ATM switch that allows
geographically dispersed stations on connected LANs to be logically
grouped. Such grouping provides easy access within the workgroup,
while ensuring privacy between workgroups and limiting the impact of
the work of each group on the others.
virtual telecommunications access
method
- See VTAM.
Virtual Terminal Protocol
- See VTP.
- Virtual LAN. Group of
devices on a LAN that are configured (using management software) so
that they can communicate as if they were attached to the same wire,
when in fact they are located on a number of different LAN segments.
Because VLANs are based on logical instead of physical connections,
they are extremely flexible.
- Virtual LAN internetwork.
Internetwork composed of VLANs. See VLAN.
- Variable-length subnet mask.
Ability to specify a different subnet mask for the same network
number on different subnets. VLSM can help optimize available
address space.
VNS
- Virtual path connection.
Grouping of VCCs that share one or more contiguous VPLs. See also VCC
and VPL.
- Virtual path identifier.
8-bit field in the header of an ATM cell. The VPI, together with the
VCI, is used to identify the next destination of a cell as it passes
through a series of ATM switches on its way to its destination. ATM
switches use the VPI/VCI fields to identify the next VCL that a cell
needs to transit on its way to its final destination. The function
of the VPI is similar to that of the DLCI in Frame Relay. Compare
with DLCI.
See also VCI
and VCL.
- Virtual path link.
Within a virtual path, a group of unidirectional VCLs with the same
end points. Grouping VCLs into VPLs reduces the number of
connections to be managed, thereby decreasing network control
overhead and cost. A VPC is made up of one or more VPLs.
- Virtual telecommunications
access method. Set of programs that control communication
between LUs. VTAM controls data transmission between
channel-attached devices and performs routing functions.
- Virtual Terminal Protocol. ISO application for establishing a virtual terminal connection across a network.