Cell queuing in ATM switches

摘要

In a network switch, data received on an input connection can be transmitted on one or more output connections. When the switch receives a command to remove an output connection, the switch queues a marker cell in a queue cells to be transmitted on the output connection. The switch removes the connection when the switch reaches the marker cell as the switch traverses the queue to transmit the cells. A separate queue is provided for each input connection. For each input connection, the switch maintains a linked list of data structures each of which identifies an output connection which is to transmit data received on the input connection but for which the corresponding queue does not have data ready to be transmitted. When the queue gets data ready to be transmitted on all the output connections in the linked list, these output connections are moved to another linked list maintained for output connections for which there is a queue having data ready to be transmitted. The switch mutliplexes two different input connections onto the same virtual output connection. This virtual output connection can be multiplexed with other connections on the same port or sub-port. The cells are transmitted on the virtual output connection in frames. The cells of each frame are transmitted without any intervening cells. Thus, in an ATM network different input connections can be multiplexed on the same virtual output connection using the AAL-5 protocol.