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Glossary

VCC

Virtual Channel Connection: A logical circuit that is created by

VCLs. VCCs carry data between two endpoints in an ATM network. Some-
times called a virtual circuit connection.

VIP

1) Versatile Interface Processor: An interface card for Cisco 7000 and

7500 series routers, providing multilayer switching and running the Cisco
IOS software. The most recent version of VIP is VIP2. 2) Virtual IP: A func-
tion making it possible for logically separated switched IP workgroups to
run Virtual Networking Services across the switch ports of a Catalyst 5000.

virtual circuit

Abbreviated VC, a logical circuit devised to assure reliable

communication between two devices on a network. Defined by a virtual path
connection (VPC)/virtual path identifier (VCI) pair, a virtual circuit can be
permanent (PVC) or switched (SVC). Virtual circuits are used in Frame
Relay and X.25. Known as virtual channel in ATM. See also: PVC and SVC.

virtual link

Used to attach an OSPF area to Area 0 across an area other

than Area 0.

virtual ring

In an SRB network, a logical connection between physical

rings, either local or remote.

VLAN

Virtual LAN: A group of devices on one or more logically seg-

mented LANs (configured by use of management software), enabling devices
to communicate as if attached to the same physical medium, when they are
actually located on numerous different LAN segments. VLANs are based on
logical instead of physical connections and thus are tremendously flexible.

VLSM

Variable-Length Subnet Mask: Helps optimize available address

space and specify a different subnet mask for the same network number on
various subnets. Also commonly referred to as "subnetting a subnet."

VPN

virtual private network: A method of encrypting point-to-point log-

ical connections across a public network, such as the Internet. This allows
secure communications across a public network.

VTP

VLAN Trunk Protocol: Used to update switches in a switch-fabric

about VLANs configured on a VTP server. VTP devices can be a VTP server,
client, or transparent device. Servers update clients. Transparent devices are
only local devices and do not share information with VTP clients. VTPs send
VLAN information down trunked links only.

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