# US 5,345,558 A · Topology independent broadcast of cells in an ATM network or the like > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,345,558 A - Document ID: US5345558A - Status: Granted - Kind: A - Application number: 07/980,253 - Filed: 1992-11-23 - Granted: 1994-09-06 - Earliest claimed: 1992-11-23 - Assignees: SynOptics Communications, Inc. - Inventors: Ayal Opher; Dilip Chatwani; Rajan Subramanian - Web page: https://patentgrep.com/patent/US5345558A ## CPC - H04Q 11/0478: {Provisions for broadband connections} - H04L 49/203: {ATM switching fabrics with multicast or broadcast capabilities} - H04L 2012/5619: {Network Node Interface, e.g. tandem connections, transit switching} - H04L 2012/5652: {Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly} - H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A topology-independent method and apparatus for avoiding continuous looping of transmission of cells and for allowing broadcast of cells in a network implementing Asynchronous Transfer Mode ("ATM") or similar networking architectures. The disclosed method and apparatus provides for "misusing" fields in a cell header in order to provide for information identifying a cell as a broadcast cell and to provide for "expiration information" in the cell header. More specifically, a first station stores data in a first area of a cell intended for transmission on the network, where the first area is defined by standards to store certain information (in particular, it is defined in the preferred embodiment to store virtual path identifier information, VPI). The information stored identifies the cell as a broadcast cell. In other words, the field is "misused" to store this information. The first station further stores in a second field, also defined by the standard to store certain information (in particular, virtual channel identifier information, VCI), information which allows for expiration of the cell. Thus, this second field is also "misused". The cell is then transmitted onto the network, copied and forwarded out of multiple ports of each switch, until the cell "expires". In the described embodiment, the "expiration information" is implemented as a hop count. ## Claims ### Claim 1 A method for broadcast of cells in a network implementing Asynchronous Transfer Mode comprising the steps of: (a) a first station on said network formatting a cell for broadcast, said step of formatting said cell comprising the steps of: i) assembling a header area comprising a first area and a second area, said first area being set to a predetermined value to indicate said cell is a broadcast cell, said second area being set to contain expiration information; ii) assembling a third area having therein user information; (b) said first station transmitting said cell onto said network; (c) said cell being received by a fast switch; (d) said first switch determining if said fast area is set to said first predetermined value; and, if said fast switch is so set; (e) said fast switch accessing said second area to determine if said cell should be forwarded. ### Claim 2 (depends on 1) The method as recited by claim 1 wherein said fast area is a virtual path identifier, also referred to with the acronym VPI. ### Claim 3 (depends on 1) The method as recited by claim 1 wherein said predetermined value is all 1's. ### Claim 4 (depends on 1) The method as recited by claim 1 wherein said second area is a virtual channel identifier, also referred to with the acronym VCI. ### Claim 5 (depends on 1) The method as recited by claim 1 wherein said step (e) of accessing said expiration information comprises the step of decrementing said expiration information. ### Claim 6 (depends on 1) The method as recited by claim 1 wherein said step (e) of accessing said expiration information comprises the step of decrementing said expiration information by 1. ### Claim 7 (depends on 1) The method as recited by claim 1 wherein said step (e) of accessing said expiration information comprises the step of decrementing said expiration information by greater than 1. ### Claim 8 (depends on 1) The method as recited by claim 1 wherein said step (e) of accessing said expiration information comprises the step of incrementing said expiration information. ### Claim 9 A network implementing Asynchronous Transfer Mode comprising: (a) a fast station on said network for formatting and transmitting a cell, said cell comprising: i) a first area being a header, said header having a first identifier field and a second identifier field, said fast identifier field set to a predetermined value to indicate said cell is a broadcast cell, said second identifier field set to a count value; ii) a second area having therein user information; and (b) a first switch for determining if said fast identifier is set to said fast predetermined value and, if said first switch is so set, for altering the count value in said second identifier field. ### Claim 10 (depends on 9) The network as recited by claim 9 wherein said first identifier field is a virtual path identifier, also referred to with the acronym VPI. ### Claim 11 (depends on 9) The network as recited by claim 9 wherein said predetermined value is all 1's. ### Claim 12 (depends on 9) The network as recited by claim 9 wherein said second identifier field is a virtual channel identifier, also referred to with the acronym VCI. ### Claim 13 (depends on 9) The network as recited by claim 9 wherein said count value is altered by decrementing said count value. ### Claim 14 (depends on 9) The network as recited by claim 9 wherein said count value is altered by decrementing said count value by 1. ### Claim 15 The network as recited by 9 wherein said count value is altered by decrementing said count value by greater than 1. ### Claim 16 A method for broadcast of a packet in a computer network implementing Asynchronous Transfer Mode, where said packet having a first area comprising information about said packet and a second area comprising user information, said first area having a plurality of fields including a first field and a second field, said method comprising the steps of: a) a first node on said network formatting said packet for broadcast, said step of formatting said packet for broadcast including the steps of: i) populating said first field with a predetermined value, and ii) populating said second field with a count value, b) said first node transmitting said packet onto said network; c) said packet being received by a first switch; d) said first switch determining if said first field is set to said predetermined value; and, if said first field is set to said predetermined value, e) said first switch altering said count value in said second field. ### Claim 17 (depends on 16) The method as recited by claim 16 wherein said first field is a virtual path identifier, also referred to with the acronym VPI. ### Claim 18 (depends on 16) The method as recited by claim 16 wherein said second field is a virtual channel identifier, also referred to with the acronym VCI. ### Claim 19 (depends on 16) The method as recited by claim 16 wherein said predetermined value is all 1's. ### Claim 20 (depends on 16) The method as recited by claim 16 wherein said step (e) of altering said count value comprises the step of decrementing said count value. ### Claim 21 (depends on 16) The method as recited by claim 16 wherein said step (e) of altering said count value comprises the step of decrementing said count value by 1. ### Claim 22 (depends on 16) The method as recited by claim 16 wherein said step (e) of altering said count value comprises the step of decrementing said count value by greater than 1. ### Claim 23 A computer network implementing Asynchronous Transfer Mode providing for broadcast of a packet, where said packet having a first area comprising information about said packet and a second area comprising user information, said first area having a plurality of fields including a first field and a second field, said computer network comprising: a) a first node on said network for formatting a packet for broadcast by: i) populating said first field with a predetermined value, and ii) populating said second field with a count value, b) said first node transmitting said packet onto said network; c) a first switch for receiving said packet; d) said first switch determining if said first field is set to said predetermined value; and, if said first field is set to said predetermined value and, e) said first switch altering said count value in said second field. ### Claim 24 (depends on 23) The computer network as recited by claim 23 wherein said first field is as a virtual path identifier, also referred to with the acronym VPI. ### Claim 25 (depends on 23) The computer network as recited by claim 23 wherein said second field is a virtual channel identifier, also referred to with the acronym VCI. ### Claim 26 (depends on 23) The computer network as recited by claim 23 wherein said predetermined value is all 1's. ### Claim 27 (depends on 23) The computer network as recited by claim 23 wherein said said first switch alters said count value by decrementing said count value. ### Claim 28 (depends on 23) The computer network as recited by claim 23 wherein said said first switch alters said count value by decrementing said count value by 1. ### Claim 29 (depends on 23) The computer network as recited by claim 23 wherein said said first switch alters said count value by decrementing said count value by greater than 1. ### Claim 30 A method for avoiding continuous forwarding of cells in a network implementing Asynchronous Transfer Mode comprising the steps of: (a) a first station on said network formatting a cell for broadcast, said step of formatting said cell comprising the steps of: i) assembling a header area comprising a first area and a second area, said first area being set to a predetermined value to indicate said cell is a broadcast cell, said second area being set to a count value; ii) assembling a third area having therein user information; (b) said first station transmitting said cell onto said network; (c) said cell being received by a first switch; (d) said first switch determining if said first area is set to said predetermined value; and, if said first switch is so set; (e) said first switch altering the count value in said second area. ### Claim 31 (depends on 30) The method as recited by claim 30 wherein said Fast area is a virtual path identifier, also referred to with the acronym VPI. ### Claim 32 (depends on 30) The method as recited by claim 30 wherein said predetermined value is all 1's. ### Claim 33 (depends on 30) The method as recited by claim 30 wherein said second area is a virtual channel identifier, also referred to with the acronym VCI. ### Claim 34 (depends on 30) The method as recited by claim 30 wherein said step (e) of altering said count value comprises the step of decrementing said count value. ### Claim 35 A computer network implementing Asynchronous Transfer Mode providing for broadcast of a cell, where said cell having a first area comprising information about said cell and a second area comprising user information, said first area having a plurality of fields including a first field for storing first information and a second field for storing second information, said computer network comprising: a) a first node on said network for formatting a cell for broadcast by: i) populating said first field with a first predetermined value, said first predetermined value representing said cell is a broadcast cell; and ii) populating said second field with a second predetermined value, said second predetermined value further representing said cell is a broadcast cell; b) said first node transmitting said cell onto said network; c) a first switch for receiving said cell; d) said first switch determining if said first field is set to said first predetermined value and if said second field is set to said second predetermined value; and, if so set, e) said first switch further altering said second field to contain a count value. ### Claim 36 (depends on 35) The computer network as recited by claim 35 wherein said first field is as a virtual path identifier, also referred to with the acronym VPI and said first predetermined value is 0. ### Claim 37 (depends on 35) The computer network as recited by claim 35 wherein said second field is a virtual channel identifier, also referred to with the acronym VCI, and said second predetermined value is 2. ### Claim 38 (depends on 35) The computer network as recited by claim 35 further comprising the step of altering said first field after step (e). ### Claim 39 (depends on 38) The computer network as recited by claim 38 wherein said first field is altered to contain all 1's.