A permanent virtual circuit (PVC) is a logical network connection provisioned in advance between specified endpoints and kept configured for the service term. It is not a dedicated physical cable: the connection is a virtual path through a network, and “permanent” describes how it is provisioned, not a guarantee that it cannot fail.
What “permanent virtual circuit” means
A network operator or service provider sets up a PVC ahead of use rather than having the endpoints establish a new connection whenever they need one. Cisco uses the term in ATM and Frame Relay contexts; in ATM documentation, PVC is also expanded as “permanent virtual connection.” The core idea is the same: a logical link between defined endpoints that is maintained by configuration.
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In Cisco’s ATM service description, the PVC crosses a service-provider network and is provisioned with the bandwidth purchased by the customer. That description is specific to the service context Cisco discusses; it does not mean every PVC technology has the same bandwidth guarantees or resilience.
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PVC vs. SVC
A switched virtual circuit (SVC) is established dynamically on demand through network signaling. Cisco’s comparison describes an SVC as potentially being removed after an idle interval; a PVC, by contrast, is provisioned in advance. The distinction is about how the logical connection is established and maintained, not whether either is a physical cable.
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| Feature | PVC | SVC |
|---|---|---|
| How it is established | Manually provisioned by a network operator in Cisco’s ATM example. | Established dynamically by end devices through network signaling. |
| Typical duration in Cisco’s ATM description | May persist from a month to several years, or until the service is terminated; this is an example, not a universal limit. | On demand; Cisco says it may be torn down after an idle timeout. |
| Operational implication | The configuration is maintained in advance. | Endpoints initiate the connection when needed; after a failure, the call may need to be initiated again. |
These details reflect Cisco’s ATM FAQ, not a rule for every vendor’s equipment or every network service. Cisco’s stated default SVC idle timeout, in particular, should not be treated as universal.
How an ATM PVC is configured
In Cisco’s IOS XE 17 ATM configuration guide, a PVC is configured on both the router and the ATM switch and remains active until it is removed from either configuration. The guide identifies a PVC using a virtual path identifier/virtual channel identifier (VPI/VCI); interface protocol and encapsulation settings are also required.
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Exact commands, identifier ranges, signaling, and encapsulation depend on the equipment and service configuration. The definition alone is not enough to produce a working connection, and a router by itself is not sufficient under the cited setup guidance.
Related ATM term: permanent virtual path
A permanent virtual path (PVP) is a set of PVCs in Cisco’s ATM terminology. A PVC is a virtual link between two specified endpoints across an ATM network. This distinction is useful when reading ATM network documentation: the PVP describes a grouping of virtual circuits, while a PVC is the individual logical connection.
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Sources and scope
- Cisco ATM PVC, SVC, Soft-PVC, and PVP FAQ (updated February 14, 2019): definition and PVC/SVC comparison.
- Cisco IOS XE 17 ATM configuration guide: configuration context for the documented platform.
- Cisco Link Fragmentation and Interleaving for Frame Relay and ATM Virtual Circuits: terminology.
- Cisco VP (Virtual Path) Switching and Tunnels: PVP context.
The definition and setup details here describe Cisco’s ATM terminology and documented configuration. They should not be read as a survey of current PVC deployment across all providers or network technologies.
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