QOS aware expansion mechanism
View Patent ↗In a data communication system comprising a plurality of peripherals having respective interfaces, the interfaces having device drivers and being coupled to a common bus for communication with a management system, the interfaces having different real time requirements; an ATM SAR and scheduler employs a predefined PHY level interface with different levels of service, the PHY interface being used as a QOS (Quality of Service) aware common master-slave bus for the peripherals which act as slave devices, whereby respective device driver requirements can be simplified or eliminated. A predefined PHY level interface is the ATM Forum UTOPIA, each peripheral being addressed as a separate UTOPIA slave port. The invention discloses how a system required to support interfaces with differing real time requirements may be supported through the use of a common bus.
1. A system, comprising:
a plurality of peripheral devices, each of the plurality of peripheral devices configured to specify its minimum quality of service (QOS) level; and
a physical layer device coupled to the plurality of peripheral devices, the physical layer device configured to assign the minimum QOS level for each of the plurality of peripheral devices and schedule services to meet the assigned QOS level for each of the plurality of peripheral devices,
wherein at least one of the plurality of peripheral devices is a Time Division Multiplexing (TDM) peripheral device, wherein in hardware, the TDM peripheral device utilizes a physical (PHY) level interface for frame timing logic and serialization, and in software, the TDM peripheral device is configured to treat a TDM interface as a constant bit rate (CBR) stream of data, and
wherein at least one of the plurality of peripheral devices is an HDLC peripheral device, wherein in hardware, the high-level data link control (HDLC) peripheral device uses the PHY level interface as a bus to simulate timing logic, serialization logic and cell buffers, and in software, the HDLC peripheral device is configured to treat the HDLC interface as a variable bit rate (VBR) stream of data with peak cell rate (PCR) equal to the HDLC controller's line rate and with burst size equal to packet length.
2. A system according to claim 1 , wherein the physical layer device comprises an asynchronous transfer mode (ATM) segmentation and reassembly (SAR) and scheduler device.
3. A system according to claim 2 , wherein the ATM SAR and scheduler provides pacing functions for the plurality of peripherals according to predefined ATM traffic classes.
4. A system according to claim 3 , wherein the ATM SAR and scheduler implements a variable bit rate traffic class.
5. A system according to claim 1 , wherein the physical layer device is a master device and each of the plurality of peripherals is addressed by the physical layer device as a separate slave port.
6. A system according to claim 1 , wherein the plurality of peripheral devices employ at least two of time division multiplexing (TDM), high-level data link control (HDLC), Ethernet, and shared memory resources.
7. A system according to claim 1 , wherein a VPI/VCI field is utilized as an HDLC address to offer quality of service for individual packets to specific addresses.
8. A system according to claim 1 , wherein peripheral devices working with shared memory and their associated real time streaming requirements redefine an ATM VPI/VCI field as an address within a shared memory, leaving other flow control fields to provide processor interlocks.
9. A system according to claim 1 , wherein at least one of the plurality of devices is an Ethernet peripheral device, the Ethernet peripheral device programming a scheduler to implement a VBR traffic class with a PCR equal to the Ethernet line rate and a burst size equal to the longest Ethernet packet.
10. A system according to claim 1 , wherein the predefined PHY level interface is internal and wherein the peripheral is addressed by a respective port number.
11. A system according to claim 1 , wherein a dual ported memory is constructed by using an ATM cell VPI/VCI fields as the address of location(s) within the dual ported memory.
12. A system according to claim 1 , wherein at least one of the plurality of devices is an MPEG decoder peripheral device, the MPEG decoder peripheral device addressed by the physical layer device and a video stream is delivered with the minimum QOS level to maintain decoder picture quality.
13. A method, comprising:
receiving a minimum quality of service (QOS) level from each of a plurality of peripheral devices;
assigning in a physical layer device the minimum QOS level for each of the plurality of peripheral devices; and
scheduling services to meet the assigned QOS level for each of the plurality of peripheral devices,
wherein at least one of the plurality of peripheral devices is a Time Division Multiplexing (TDM) peripheral device, wherein in hardware, the TDM peripheral device utilizes a physical (PHY) level interface for frame timing logic and serialization, and in software, the TDM peripheral device is configured to treat a TDM interface as a constant bit rate (CBR) stream of data, and
wherein at least one of the plurality of peripheral devices is an HDLC peripheral device, wherein in hardware, the high-level data link control (HDLC) peripheral device uses the PHY level interface as a bus to simulate timing logic, serialization logic and cell buffers, and in software, the HDLC peripheral device is configured to treat the HDLC interface as a variable bit rate (VBR) stream of data with peak cell rate (PCR) equal to the HDLC controller's line rate and with burst size equal to packet length.
14. A method according to claim 13 , wherein the physical layer device comprises an asynchronous transfer mode (ATM) segmentation and reassembly (SAR) and scheduler device.
15. A method according to claim 13 , wherein an ATM SAR and scheduler further comprising providing pacing functions for the plurality of peripherals according to predefined ATM traffic classes.
16. A method according to claim 13 , wherein the physical layer device is a master device and each of the peripherals is addressed by the physical layer device as a separate slave port.