Invalidity dossier
US 5592476
Asynchronous transfer mode switch with multicasting ability
Current assignee: Hewlett Packard Development Co LP
Added 9/23/2026, 4:50:25 PM
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Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US 5,592,476 A
Title: Asynchronous transfer mode switch with multicasting ability
Patent number / application: US 5,592,476 A; application US 08/422,156, filed 1995-04-14.
Inventors: Costas Calamvokis and David Banks.
Assignee: Original assignee Hewlett Packard Ltd; current assignee listed as Hewlett Packard Development Co LP.
Dates: Prior art date 1994-04-28; filing date 1995-04-14; publication/grant date 1997-01-07; anticipated expiration 2015-04-14; status "Expired - Lifetime." (The source notes legal status is an assumption, not a legal conclusion, and that listed assignees may be inaccurate.)
Purpose: According to the supplied text, the invention "relates generally to multicasting apparatus for multicasting packets (including fixed-length packets or 'cells'); in particular, but not exclusively, the present invention relates to an ATM switch with cell multicasting capability." It addresses ATM, described as a multiplexing and switching technique using fixed-size cells appearing strictly periodically on the physical medium, with a payload and a header containing a context-dependent label. The source presents the invention as "applicable generally to ATM systems (and other systems) independently of specific implementation details such as cell size," and says claims referring to ATM "should be accordingly interpreted."
Plain-language scope: The patent concerns apparatus for copying packets/cells to multiple destinations, and specifically a switch for ATM cells, with the underlying ATM discussion framed around B-ISDN UNI cell formats for AAL5 services and the CCITT/ATM Forum standards. Classification is H04L12/18 and H04L12/1881 (multicast, including schedule organisation).
What the excerpt does not establish: It contains no claims text, no detailed description of the switching/multicasting mechanism, no figures, and no named prior-art references. It therefore cannot support any statement about specific claim scope, novelty, validity, infringement, or comparison to prior art. Ownership transfers and litigation are outside this overview, per instruction.
Source: https://patents.google.com/patent/US5592476/en (excerpted; consult the source for omitted text).
Generated 10/1/2026, 9:44:07 PM
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Litigation summary
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Proceedings on file (0)
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PTAB challenges
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Assignment history
Inventors, original assignee, and the chain of ownership recorded with the USPTO — including the correspondent attorney who recorded each assignment, since shell-LLC chains often share one repeat-player attorney even when the entity names look unrelated. Surfaces NPE / patent-troll patterns: shell-entity transfers, known asserters in the chain, repeat correspondent fingerprints, pre-litigation assignments, and bankruptcy fire-sales.
Prior art
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Obviousness
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Extensions
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Derivative works
Defensive disclosure: derivative variations of each claim designed to render future incremental improvements obvious or non-novel.