Method for scheduling ATM cells and a device having ATM cell scheduling capabilities
View Patent ↗A method for scheduling a transmission of ATM cells, the method includes: receiving an indication that a scheduling session should starts; and repeating the stages of: selecting a channel representative queue out of multiple queues that are associated with different quality of service traffic threads that belong to that channel; scheduling a transmission of frames from channel representative queues and from single queue channels; wherein the scheduling comprises processing a scheduling table that comprises multiple sets of entries, wherein each set of entries is associated with a different transmission priority level, and wherein at least one set of entries comprises a link to a transmission parameter table that is associated with a channel representative queue.
1. A method for scheduling a transmission of asynchronous transfer mode (ATM) cells, the method comprises:
receiving at a communication controller an indication that a session for scheduling ATM cells in the communication controller starts;
in response to receiving the indication, selecting, by the communication controller, a channel representative queue of a plurality of channel representative queues, the plurality of channel representative queues being associated with a multiple queue channel, wherein the plurality of channel representative queues are each associated with a different quality of service traffic thread of the multiple queue channel;
selecting from a scheduling table a particular set of entries from among a plurality of sets of entries, wherein:
each set of entries of the plurality of sets of entries is associated with a different channel having a different transmission priority level;
a first set of entries of the plurality of sets of entries includes a first link to a first channel transmission parameter table associated with the multiple queue channel; and
a second set of entries of the plurality of sets of entries include a second link to a second channel transmission parameter table associated with a single queue channel; and
in response to selecting the particular set of entries, transmitting, by the communication controller, an ATM cell.
2. The method according to claim 1 :
wherein each of the plurality of channel representative queues comprises multiple buffer descriptors;
the method further comprising:
associating each buffer descriptor with a buffer that stores ATM cells to be transmitted: and
associating a set of buffer descriptors with the first channel transmission parameter table.
3. The method according to claim 1 wherein the selecting from the scheduling table is based upon a leaky bucket algorithm.
4. The method according to claim 1 wherein the selecting the channel representative queue is based upon a weighted fair queue algorithm.
5. The method according to claim 1 wherein the selecting from the scheduling table further comprises:
accessing a particular transmission parameter table; and
searching for a channel representative queue flag indicating whether the particular transmission parameter table is associated with the channel representative queue or with the single queue channel.
6. The method according to claim 1 wherein if the particular set of entries is the second set of entries, then the method further comprises:
accessing a buffer descriptor table pointed to by the second channel transmission parameter table;
transmitting an ATM cell stored in buffer registers that are linked to the buffer descriptor table; and
updating the scheduling table to reflect the last transmission.
7. The method according to claim 1 wherein if the particular set of entries is the first set of entries, then the method further comprises:
accessing a queue transmission parameter table associated with the channel representative queue;
accessing a buffer descriptor table associated with the queue transmission parameter table;
transmitting an ATM cell stored in buffer registers that are linked to the buffer descriptor table;
updating the scheduling table to reflect the last transmission; and
updating the queue transmission parameter table to indicate that an ATM cell from the channel representative queue was transmitted.
8. A device for scheduling a transmission of asynchronous transfer mode (ATM) cells, the device comprises:
a memory unit adapted to store multiple buffers;
a communication controller adapted to:
select a channel representative queue out of a plurality of channel representative queues, wherein the plurality of channel representative queues are each associated with a different quality of service traffic thread, and the plurality of channel representative queues are each associated with a respective multiple queue channel;
select from a scheduling table a particular set of entries from among a plurality of sets of entries, wherein:
each set of entries of the plurality of sets of entries is associated with a different channel having a different transmission priority level;
a first set of entries of the plurality of sets of entries includes a first link to a first channel transmission parameter table associated with the multiple queue channel; and
a second set of entries of the plurality of sets of entries includes a second link to a second channel transmission parameter table associated with a single queue channel; and
in response to selecting the particular set of entries, schedule a transmission of ATM cells from the plurality of channel representative queues and from a single queue channel.
9. The device according to claim 8 wherein:
each of the plurality of channel representative queues comprises multiple buffer descriptors; and
the device is adapted to associate buffer descriptors with buffers that store the ATM cells to be transmitted and to associate a set of buffer descriptors with the transmission parameter table.
10. The device according to claim 9 , wherein the communication controller is adapted to access the transmission parameter table and to search for a channel representative queue flag indicating whether the transmission parameter table is associated with the channel representative queue or with a single queue channel.
11. The device according to claim 9 wherein the communication controller is adapted to transmit the ATM cells in response to the scheduling.
12. The device according to claim 9 wherein the communication controller is adapted to apply a leaky bucket algorithm.
13. The device according to claim 8 wherein the communication controller is adapted to transmit the ATM cells in response to the scheduling.
14. The device according to claim 8 wherein the communication controller is adapted to apply a leaky bucket algorithm.
15. The device according to claim 8 wherein the communication controller is adapted to apply a weighted fair queue algorithm.
16. The device according to claim 8 wherein the communication controller is adapted to select an entry of the scheduling table, read a channel transmission parameter table associated to the selected entry, and determine whether the channel transmission parameter table is a single queue channel transmission parameter table or a multiple queue channel transmission parameter table.
17. The device according to claim 16 wherein if the channel transmission parameter table is a single queue channel transmission parameter table then the communication controller is adapted to access a buffer descriptor table pointed by the channel transmission parameter table, transmit the ATM cells stored in buffer registers that are linked to the buffer descriptor table, and update the scheduling table to reflect the last transmission.
18. The device according to claim 16 wherein if the channel transmission parameter table is a multiple queue channel transmission parameter table then the communication controller is adapted to access a queue transmission parameter table currently associated with the multiple queue channel transmission parameter table, access a buffer descriptor table associated with the queue transmission parameter table, transmit the ATM cells stored in buffer registers that are linked to the buffer descriptor table, update the scheduling table to reflect the last transmission, and update the queue transmission parameter table to indicate that a particular ATM cell from this queue was transmitted.