It's Virtually Like a Leased Circuit, So Let's Call It a Virtual Circuit

It's Virtually Like a Leased Circuit, So Let's Call It a Virtual Circuit

In Frame Relay lingo, the ability for R1 to send data to R2 over the Frame Relay network is called a virtual circuit (VC). A VC is like a leased circuit, in that exactly two devices can send and receive data using it. It's called virtual to contrast it with a physical leased circuit. And because a VC is typically predefined to always be there, VCs are often called permanent virtual circuits (PVCs).

When you're drawing network diagrams, it is useful to show PVCs separately from the physical cabling, as shown in Figure 15-4. (Frankly, there's no real standard for how to draw a PVC, so I tend to draw a single PVC with an odd-style of linereally three parallel linesas shown in the figure.)