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Glossary

do not have a fixed-time relationship between samples, but still need an
assured QoS.

VCC

virtual channel connection: A logical circuit that is created by VCLs.

VCCs carry data between two endpoints in an ATM network. Sometimes
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 (VC)

A logical circuit devised to assure reliable communica-

tion 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 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 segmented

LANs (configured by use of management software), enabling devices to com-
municate 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.

VLAN ID

Sometimes referred to as VLAN color, the VLAN ID is tagged onto

a frame to tell a receiving switch which VLAN the frame is a member of.

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."

VMPS

VLAN Management Policy Server: Used to dynamically assign

VLANs to a switch port.

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.

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