Digital communication system for simultaneous transmission of data from constant and variable rate sources
First Claim
1. A communication system comprising a plurality of nodes coupled to a common bus, said plurality of nodes comprising at least one node adapted to communicate CBR traffic and at least one other node adapted to communicate non-CBR traffic on said common bus, each of said plurality of nodes having an access controller operative to control transmission of data on said common bus such that said CBR traffic has priority over said non-CBR traffic, wherein said common bus comprises a transmit path and a return receive path, traffic on said common bus being carried in cells each having an active bit for indicating whether said cell is in an empty or idle state or in an active state, and a request priority field for indicating a priority of request for transmission access to said common bus by one of said nodes, and wherein said access controller of said one of a said nodes requests transmission access on said common bus by writing a priority value into a cell on said receive path, wherein said access controller transmits data on said common bus by writing into a payload field of an empty or idle cell on said transmit path, a cell on said receive path at one of said nodes requesting transmission access having a priority value equal or greater than the priority of said one node is passed unchanged, and wherein a cell on said receive path at said one node requesting transmission access having a priority value less than the priority of said one node is overwritten by said access controller in the request priority field to the priority value of the node.
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Abstract
The present invention relates to a communication system, protocol and method designed to facilitate information transfer including user and control information from CBR (Continuous Bit Rate) and/or non-CBR signal sources. Such a system, for example, is a CSS (Customer Switching System), a LAN network, a Key System, LAN hub, PABX or PBX. A number of aspects are disclosed in this specification. These include: A) a key system and/or LAN which utilizes ATM technology for the trafficking of CBR, non-CBR, or a combination thereof, B) a round robin feature which facilitates the operation of i. above, C) a cell format which facilitates the operation of i. above, D) an open and closed system architecture for i. above, E) and ATM-TP which serves as an interface for CBR to the architecture and an ATM-HP which serves as an interface for non-CBR to the architecture, F) partial cell filling for system efficiency and/or echo control, G) a staggering feature to facilitate system efficiency, H) a channel aggregation feature to reduce the requirement for external adaptor equipment, I) a by-pass feature to enhance system reliability and serviceability. An example of CBR is voice, video and "non-bursty" data. An example of non-CBR or "bursty" data is LAN data.
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Citations
17 Claims
- 1. A communication system comprising a plurality of nodes coupled to a common bus, said plurality of nodes comprising at least one node adapted to communicate CBR traffic and at least one other node adapted to communicate non-CBR traffic on said common bus, each of said plurality of nodes having an access controller operative to control transmission of data on said common bus such that said CBR traffic has priority over said non-CBR traffic, wherein said common bus comprises a transmit path and a return receive path, traffic on said common bus being carried in cells each having an active bit for indicating whether said cell is in an empty or idle state or in an active state, and a request priority field for indicating a priority of request for transmission access to said common bus by one of said nodes, and wherein said access controller of said one of a said nodes requests transmission access on said common bus by writing a priority value into a cell on said receive path, wherein said access controller transmits data on said common bus by writing into a payload field of an empty or idle cell on said transmit path, a cell on said receive path at one of said nodes requesting transmission access having a priority value equal or greater than the priority of said one node is passed unchanged, and wherein a cell on said receive path at said one node requesting transmission access having a priority value less than the priority of said one node is overwritten by said access controller in the request priority field to the priority value of the node.
Specification