8.4 Frame Relay Traffic Shaping
8.4.6 Traffic shaping examples
The Figure illustrates a typical Frame Relay environment. The central site has a T1-speed local-loop connection and the branch offices have slower (in this case, 9.6-Kbps) local-loop connections. In addition, the CIR for each PVC going from the central site to each branch office is 9.6 Kbps.

In this environment, the following process occurs:

  • The central site may send data across the T1-speed line. Even though the CIR is 9.6 Kbps, the router continues to send the data based on the T1 rate.
  • The data goes through the cloud.
  • When the data reaches the local loop that is connected to the branch office, a bottleneck occurs because the data is being sent faster than the speed of the branch-office local loop. At this point, packets are buffered at the egress point of the network, increasing line response time and (possibly) causing problems, particularly for latency-sensitive protocols such as SNA.

The solution is to slow the speed at which the central-site router is sending data. With the traffic shaping over Frame Relay feature, you can define and enforce a rate on the VC at which the router will send data. The pace you set can be the CIR, EIR, or some other value.