Scalable, high-resolution asynchronous transfer mode traffic shaper and method
View Patent ↗An ATM network traffic shaper is implemented in hardware. The traffic shaper shapes transmit data on one or more virtual circuits (VCs) according to the specified quality of service (QoS) parameters. Thus, the traffic shaper provides for the delivery of associated data cells in accordance with the specified QoS parameters. The traffic shaper is scalable in that the number of supported VCs can be increased with a relatively small increase in the size of the device and associated logic gates. The traffic shaper supports constant bit rate (CBR), variable bit rate (VBR), and unknown bit rate (UBR) service types and generates cell transmit requests with zero cell delay variation (CDVT). The traffic shaper also provides very high resolution in terms of bit rate specification. Varying shaping resolutions are achieved by varying a shaping interval time (SIT) generated by a SIT counter.
1. An apparatus, comprising:
a plurality of transmit storage devices that receive data from traffic sources;
a traffic shaper device coupled to the transmit storage device, the traffic shaper device comprising,
a parameter storage device configured to store quality of service parameter values (Pn),
a bucket storage device configured to store bucket values (Bn),
a shaper controller device coupled to the parameter storage device and the bucket storage device,
a shaper device coupled to the shaper controller device, the parameter storage device, and the bucket storage device, wherein the shaper device is configured to use the Pn and Bn values to generate cell request signals when cell requests are scheduled; and
a scheduling device coupled to the transmit storage device and the traffic shaper device and configured to schedule transmission of the data based on the cell request signals,
wherein the parameter storage device and the scheduling device are initiated using a signal from a host controller device.
2. The apparatus of claim 1 , wherein a shaping interval time (SIT) counter is coupled to the shaper controller device and the shaper device, where the SIT counter is configured to transmit a signal (SITn) to initiate the shaper controller access to the Pn and Bn values.
3. The apparatus of claim 2 , wherein the traffic shaper device is adapted to receive n sequential shaping interval time (SIT) signals of varying values from the SIT counter to individually control a shaping resolution for each of n transmit storage devices.
4. The apparatus of claim 1 , wherein the traffic shaper device is configured to perform a Dual Reverse Leaky Bucket algorithm.
5. The apparatus of claim 1 , wherein the traffic shaper device is coupled to n of the plurality of transmit storage devices, wherein the bucket storage device comprises n memory sections, and wherein one of the n memory sections corresponds to one of the n of the plurality of transmit storage devices.
6. The apparatus of claim 1 , wherein the traffic shaper device is coupled to n transmit storage devices, wherein the parameter storage device comprises n memory sections, and wherein one of the n memory sections corresponds to one of the n transmit storage devices.
7. The apparatus of claim 1 , wherein the Pn value includes at least one of a peak cell rate (PCR) value, a QoS service category value, a burst tolerance (BT) value, and a sustained cell rate (SCR) value.
8. The apparatus of claim 1 , wherein the bucket storage device stores peak cell rate (PCR) bucket values and sustained cell rate (SCR) bucket values.
9. The apparatus of claim 1 , wherein the traffic shaper device is configured to operate with substantially zero cell delay variation tolerance (CDVT).
10. The apparatus of claim 1 , wherein the traffic shaper device is configured to be scalable to accommodate n transmit storage devices.
11. The apparatus of claim 1 , wherein the shaper device comprises:
a comparator coupled to the scheduling device and the shaper controller device;
a parameter multiplexer coupled to the parameter storage device;
a bucket value multiplexer coupled to the bucket storage device;
a PCR bucket counter coupled to the comparator, the parameter multiplexer, the bucket value multiplexer, and the bucket storage device;
a SCR bucket counter coupled to the comparator, the parameter multiplexer, the bucket value multiplexer, and the bucket storage device; and
a cell requestor coupled to the PCR bucket counter, the SCR bucket counter, and the scheduling device.
12. A traffic shaper device, comprising:
a shaper controller;
a shaper device coupled to the shaper controller;
parameter storage coupled to the shaper controller and the shaper device; and
bucket value storage coupled to the shaper controller and the shaper device,
wherein the shaper device comprises,
a comparator coupled to the shaper controller,
a parameter multiplexer coupled to the parameter storage,
a bucket value multiplexer coupled to the bucket value storage,
a peak cell rate (PCR) bucket counter coupled to the comparator, the parameter multiplexer, the bucket value multiplexer, and the bucket value storage,
a sustained cell rate (SCR) bucket counter coupled to the comparator, the parameter multiplexer, the bucket value multiplexer, and the bucket value storage, and
a cell requestor coupled to the PCR bucket counter and the SCR bucket counter.
13. The traffic shaper device of claim 12 , wherein the shaper controller, the shaper device, the parameter storage, and the bucket storage are configured to result in substantially zero CDVT.
14. The traffic shaper device of claim 12 , wherein the parameter storage and the bucket storage are configured to be scalable to accommodate n transmit storage devices.