| 摘要 |
A data traffic network 200 in which excess cells, or cells whose transfer is expected to cause the user to exceed the QoS traffic contract bandwidth limit, are transferred to a destination node 300b via an alternate or secondary network 212. More particularly, traffic received at a first ATM node 300a (for example, an end user node) is or has been classified according to traffic type, such as voice, data, or video (with their corresponding characteristics). Prior to packetizing the data streams into the ATM fixed length packets, the ATM node 300a, 600a determines whether the QoS traffic contract bandwidth limit has been exceeded or is likely to be exceeded. If so, then the corresponding traffic is transmitted to the destination node 300b via an appropriate alternate network 212. For example, voice traffic is transferred to a PBX and, ultimately, to the public switched telephone network (PSTN). Once the bandwidth utilization of the ATM network 305 falls below the threshold level, all traffic is routed back through the ATM network.
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