Remember the default serial encapsulation on Cisco routers. Cisco routers use a proprietary High-Level Data-Link Control (HDLC) encapsulation on all their serial links by default.
Understand the different Frame Relay encapsulations. Cisco uses two different Frame Relay encapsulation methods on its routers: Cisco and IETF. If you are using the Cisco encapsulation method, you are telling your router that a Cisco router is installed on the other side of the PVC. If you are using the IETF encapsulation, you are telling your router that a non-Cisco router is installed on the other side of the PVC.
Remember what the CIR is in Frame Relay. The CIR is the average rate, in bits per second, at which the Frame Relay switch agrees to transfer ...