Invalidity dossier
US 5473607
Packet filtering for data networks
Current assignee: Cisco Technology Inc
Added 9/23/2026, 5:19:44 PM
Active provider: DeepSeek · deepseek-flash
Patent summary
Title, assignee, inventors, filing/issue dates, abstract, and a plain-language overview of the claims.
Patent Overview — US5473607A
Title: "Packet filtering for data networks"
Patent number / application: US5473607A (application US08/103,659)
Inventors: Richard J. Hausman; Lazar Birenbaum
Original assignee: Grand Junction Networks Inc. Current assignee listed as Cisco Technology Inc (also listed: Grand Junction Networks Inc).
Key dates: Filed 1993-08-09; priority date 1993-08-09; granted/publication 1995-12-05; anticipated expiration 2013-08-09. Status: Expired – Lifetime.
Purpose: The invention addresses field-based packet filtering in data networks. Networked devices attach via a "controller" that filters packets in real time, classifying them as rejects, exact matches, or partial matches, so as to reduce the burden on the host processor. The patent targets the predominant prior-art partial-filtering method, "hashing," which uses a single hash value that "potentially represents a large set of candidates," implying a loss of information.
Plain-language scope: Instead of one hashing function, the preferred embodiment applies multiple independent hashing functions in parallel to a packet's "candidate field" (the extracted relevant fields). Their combined results form a "hash matrix," where filter parameters are the set of acceptable result values for each hashing operation. The hashing functions may differ, or the same function may be applied to different subsets of the candidate field, or a combination. The stated advantages: improved partial-filtering efficiency, geometrically increased efficiency with more target memory, minimum target memory for a given efficiency, and minimum filtering time.
Classification: H04L45/745 (address table lookup; address filtering); H04L12/4625; H04L9/40.
Not established by the excerpt: the full claim language; complete description or omitted figures (e.g., FIG. 6 is cut off); the detailed embodiments; any prior-art references actually cited during prosecution; and the diagrams' contents. No litigation, ownership-transfer, validity, or prior-art conclusions are drawn here.
Source: https://patents.google.com/patent/[US5473607](/patent/US5473607)/en
Generated 10/1/2026, 9:43:40 PM
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Litigation summary
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PTAB challenges
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Assignment history
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Prior art
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Obviousness
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Extensions
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Derivative works
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