ADTRAN Atlas 550 - Manual (Page 216)

Appendix B. OSI Model and Frame Relay Technology Overview
B-4 ATLAS 550 User Manual 61200305L1-1
gotiation of the bandwidth parameters during the circuit setup. SVCs are
currently unavailable from most frame relay providers, and ATLAS only
supports PVCs.
PVC Physical Connections
Figure B-1 illustrates three PVCs being delivered over one physical circuit.
The frame relay switch within the frame relay provider’s circuit makes a
physical connection for each PVC. Each of the PVCs could connect to a dif-
ferent physical location at the other end of the circuit. Figure B-2 illustrates
a frame relay network topology.
Figure B-1. Three Virtual Circuits in One Physical Circuit
Figure B-2. Frame Relay Network using Virtual Circuits
PVC Y
128 kbps
PVC X
768 kbps
PVC Z
32 kbps
Virtual circuit Y
Virtual circuit X A
Frame Relay/Router
D
Frame Relay/Router
Virtual circuit Z
C
Frame Relay/Router
B
Frame Relay/Router Frame Relay
Network