EP0523874A2
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EP
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Method for operating an asynchronous packet bus for transmission of asynchronous and isochronous information
Assignee: AT&T Inc
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Filing: 1992-06-26
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Granted: —
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Expires: 2012-06-26
Abstract
Abstract A facility is provided for operating an asynchronous packet transmit bus (140) such that isochronous information packets may be transmitted from a source to a destination with a fixed, constant delay. The fixed, constant delay is achieved by employing a bandwidth management bus (145) and assigning to port modules (110) which contend for access to the transmit bus respective levels of priority, in which the highest level of priority is associated with isochronous information and in which lower levels of priority are associated with other types of information, such as asynchronous information. In addition, each port module which transmits isochronous information is assigned at least one time slot of each frame of time slots. In this way, a port module that needs to transmit isochronous information is granted access to the transmit bus during its assigned time slot if the module asserts such highest level of priority in response to its address being transmitted over the bandwidth management bus. If the module fails to assert such priority, then the time slot is marked for open contention, thereby allowing the other port modules to contend for access to the transmit bus during that time slot.
Inventors
- 👤 Ronald C. Roposh
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 06:14
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/40; H04L12/40143; H04L12/4015; H04Q; H04Q11/00; H04Q11/04; H04Q11/0428; H04Q11/0478; H04L12/54; H04L12/56; H04L12/5601; H04L2012/5603; H04L2012/5609; H04L2012/5613; H04L2012/5614; H04L2012/5615
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
171 words
A method of arbitrating access to a transmit bus associated with a communications switch, said transmit bus being arranged for transmitting data packets between a plurality of port modules connected to said transmit bus, said method comprising the steps of defining transmit bus time frames each comprising a plurality of time slots, associating said port modules with respective levels of priority, allocating at least one of said time slots of each of said frames to at least one of said port modules associated with the highest level of priority, and CHARACTERIZED BY transmitting over another bus, during a predetermined interval of a current one of said frames, an address identifying said at least one port module and granting to said at least one port module access to said transmit bus during said at least one time slot of said current frame if said at least one port module contends for such access by asserting said highest level of priority in response to the transmission of its address over said other bus.
Claim 2
Dependent Claim
25 words
The method set forth in claim 1 FURTHER CHARACTERIZED BY using as said predetermined interval a time slot that next precedes said one time slot.
Claim 3
Dependent Claim
82 words
The method set forth in claim 2 FURTHER CHARACTERIZED BY declaring said next preceding time slot an open contention period in the event that said at least one port module does not assert said highest level of priority, and, of the port modules who are asserting their respective levels of priority in response to said open contention, granting such access during said one time slot of the current frame to the port module that is asserting the relatively highest level of priority.
Claim 4
Dependent Claim
97 words
The method set forth in claim 2 FURTHER CHARACTERIZED BY declaring said next preceding time slot an open contention period in the event that said at least one port module does not assert said highest level of priority and, of the port modules who are asserting their respective levels of priority in response to said open contention, granting to those of the port modules that are asserting the same relatively highest level of priority access to said transmit bus during respective succeeding ones of the open time slots of said current frame including said one time slot.
Claim 5
Dependent Claim
44 words
The method set forth in claim 4 FURTHER CHARACTERIZED IN THAT said step of declaring and granting includes the step of granting such access to the port modules asserting the same relatively highest level of priority based on the order of their respective addresses.
Claim 6
Dependent Claim
45 words
The method set forth in claim 5 FURTHER CHARACTERIZED IN THAT said step of declaring and granting further includes the step of preventing at least an individual one of said port modules from obtaining such access for more than a respective predetermined number of times.
Claim 7
Dependent Claim
27 words
The method set forth in claim 1 FURTHER CHARACTERIZED IN THAT said step of defining includes the step of operating said transmit bus in an asynchronous mode.
Claim 8
Dependent Claim
74 words
The method set forth in claim 1 FURTHER CHARACTERIZED BY associating said port modules with respective data services including asynchronous and isochronous services, and wherein said highest level of priority is assigned to those of said port modules associated with said isochronous service, and lower levels of priority are assigned to those of said port modules associated with said asynchronous services, in which said isochronous and asynchronous services include connecbon oriented and comectionless services.
Claim 9
Dependent Claim
53 words
The method set forth in claim 8 wherein said at least one of said port modules is associated with said asynchronous and isochronous services, and FURTHER CHARACTERIZED BY arranging those of said port modules associated with said asynchronous service so that they contend for access to said transmit bus during oprn contention periods.
Claim 10
Dependent Claim
182 words
An arrangement for arbitrating access to a transmit bus associated with a communications switch, said transmit bus being arranged for transmitting data packets between a plurality of port modules connected to said transmit bus, said arrangement comprising means for generating a stream of transmit bus time frames each comprising a plurality of time slots, means for associating said port modules with respective levels of priority, AND CHARACTERIZED BY means for allocating at least one of said time slots of each of said frames to at least one of said port modules associated with the highest level of priority, and means for transmitting over another bus, during a predetermined time slot of a current one of said frames, an address identifying said at least one port module and for granting to said at least one port module access to said transmit bus during said at least one time slot of said currrent frame if said at least one port module contends for such access by asserting said highest level of priority in response to the transmission of its address over said other bus.
Claim 11
Dependent Claim
26 words
The arrangement set forth in claim 10 FURTHER CHARACTERIZED IN THAT said predetermined time slot is a time slot that next precedes said one time slot.
Claim 12
Dependent Claim
97 words
The arrangement set forth in claim 11 FURTHER CHARACTERIZED BY means for declaring said next preceding time slot as an open contention period in the event that said at least one port module does not assert said highest level of priority, and, responsive to a plurality of other ones of said port modules who assert their respective levels of priority in response to said open contention, for then granting such access dig said one time slot of the current frame to that one of said other port modules that is asserting the relatively highest level of priority.
Claim 13
Dependent Claim
109 words
The arrangement set forth in claim 11 FURTHER CHARACTERIZED BY means for declaring said next preceding time slot as an open contention period in the event that said at least one port module does not assert said highest level of priority and, responsive to a plurality of other ones of said port modules who assert their respective levels of priority in response to said open contention, for then granting to those of said other port modules that are asserting the same relatively highest level of priority access to said transmit bus dig respective succeeding ones of the open time slots of said current frame including said one time slot.
Claim 14
Dependent Claim
42 words
The arrangement set forth in claim 13 FURTHER CHARACTERIZED IN THAT said means for declaring and granting includes means for granting such access to said port modules asserting the same relatively highest level ofpriority based on the order of their respective addresses.
Claim 15
Dependent Claim
44 words
The arrangement set forth in claim 14 FURTHER CHARACTERIZED IN THAT said means of declaring and granting further includes means for preventing at least an individual one of said port modules from obtaining such access for more than a respective predetermined number of times.
Claim 16
Dependent Claim
26 words
The arrangement set forth in claim 10 FURTHER CHARACTERIZED IN THAT said means for generating includes means for operating said transmit bus in an asynchronous mode.
Claim 17
Dependent Claim
78 words
The arrangement set forth in claim 10 FURTHER CHARACTERIZED BY means for associating said port modules with respective data services including asynchronous and isochronous information services, and wherein said highest level of priority is assigned to those of said port modules associated with said isochronous service, and lower levels of priority are assigned to those of said port modules associated with said asynchronous services, in which said asynchronous and isochronous services may include connection oriented and/or connectionless services.
Claim 18
Dependent Claim
60 words
The arrangement set forth in claim 17 wherein said at least one of said port modules is associated with said asynchronous and isochronous information services, and wherein said arrangement is FURTHER CHARACTERIZED BY means for arranging those of said port modules associated with said asynchronous service so that they contend for access to said transrnit bus during open contention periods.
Claim 19
Dependent Claim
15 words
The arrangement set forth in claim 18 wherein said isochronous services include DS1 data rates.
Claim 20
Dependent Claim
15 words
The arrangement set forth in claim 18 wherein said isochronous services include DS3 data rates.
References Cited (Backward Citations)
No citation records indexed.
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