Frame Relay operates using virtual circuits as opposed to the actual circuits that leased lines use. These virtual circuits are what link together the thousands of devices connected to the provider’s “cloud.” Frame Relay provides a virtual circuit between your two DTE devices, making them appear to be connected via a circuit when in reality, they’re dumping their frames into a large, shared infrastructure. You never see the complexity of what’s actually happening inside the cloud because you only have a virtual circuit.
And on top of all that, there are two types of virtual circuits—permanent and switched. Permanent virtual circuits (PVCs) are by far the most common type in use today. What “permanent” means here is that the telco creates the mappings inside their gear and as long as you pay the bill, they’ll remain in place.
Switched virtual circuits (SVCs) are more like a phone call. The virtual circuit is established when data needs to be transmitted, then it’s taken down when the data transfer is complete.
And on top of all that, there are two types of virtual circuits—permanent and switched. Permanent virtual circuits (PVCs) are by far the most common type in use today. What “permanent” means here is that the telco creates the mappings inside their gear and as long as you pay the bill, they’ll remain in place.
Switched virtual circuits (SVCs) are more like a phone call. The virtual circuit is established when data needs to be transmitted, then it’s taken down when the data transfer is complete.
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