Frame Relay Traffic Flow Terminology Cont

Cisco, corn

Cisco, corn

Frame 1 Frame Z Framed Frame 4 Thlô (T=Bc/ClRJ

© 2004 Cisco Systems, Inc. All rights reserved. bcran v2.1—8-3

The CIR, by itself, does not provide much flexibility when dealing with varying traffic rates. In practice, the Frame Relay switch measures traffic over a time interval specific to each logical connection.

The Bc and Be are amounts of data that a Frame Relay network agrees to transfer over a time interval, Tc. Be is the maximum amount in excess of the Bc that the network attempts to transfer under normal conditions. The traffic that is beyond the Bc is marked with the DE bit set.

Notice that the actual frame transfer rate parallels the access rate. When a frame is being transmitted on a channel, that channel is dedicated to that transmission.

This topic describes why FRTS is used. Traffic shaping is used to control access to available bandwidth and to regulate the flow of traffic to avoid congestion that can occur when the transmitted traffic exceeds the access speed of its remote target interface.

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