An Attribute flag can be used to mark a data message as special, so that it can be identified and processed in a special way. Some attributes of messages are implicit and their automatic declarations are invisible. The union of all such customers is represented by a single compound object known as the Client . Consequently, a traffic generator in our model supplies the network directly with cells to be transmitted to their destinations. No multicast traffic is implemented at present.
Every cell is assumed to have been derived from some message.
A cell arriving at a switch is usually buffered before it can be retransmitted. Once a connection has been established, the buffering policy is the most important factor affecting the performance of the switch. The complete structure of the buffer storage depends on the buffering policy and its full specification is only possible in the context of a specific switch type. Type CBuf is generic and it must be extended to be useful. A complete buffer type will typically specify additional attributes, e.g., links needed to put the buffers into lists, sets, or more sophisticated hierarchies.