DCT

6:22-cv-00396

Corrigent Corp v. Cisco Systems Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 6:22-cv-00396, W.D. Tex., 07/12/2024
  • Venue Allegations: Plaintiff alleges venue is proper because Defendant has committed acts of infringement and maintains a regular and established place of business in the Western District of Texas.
  • Core Dispute: Plaintiff alleges that Defendant’s networking routers and switches infringe five patents related to network failure detection, latency evaluation, bandwidth allocation, and MAC address learning in telecommunications systems.
  • Technical Context: The patents relate to technologies for improving the reliability, efficiency, and performance of carrier-grade Ethernet switching and routing equipment used in large-scale telecommunications networks.
  • Key Procedural History: The complaint notes that in prior inter partes review (IPR) proceedings (IPR2023-00464, IPR2023-00837), the Patent Trial and Appeal Board (PTAB) denied institution on challenges to the ’369 patent. The complaint also references a prior district court ruling in separate litigation finding a claim of the ’369 patent eligible under 35 U.S.C. § 101. Conversely, the complaint acknowledges a prior ruling in the present case granting a motion against the ’485 patent on § 101 eligibility grounds, while reserving Plaintiff's rights on the issue. Plaintiff also alleges pre-suit notice and licensing discussions with Defendant beginning in March 2017.

Case Timeline

Date Event
2001-09-04 ’485 Patent Priority Date
2002-05-30 ’369 Patent Priority Date
2004-09-03 ’431 Patent Priority Date
2005-05-06 ’602 Patent Priority Date
2005-10-18 ’369 Patent Issued
2006-05-19 ’400 Patent Priority Date
2006-09-26 ’485 Patent Issued
2008-02-12 ’431 Patent Issued
2009-09-22 ’400 Patent Issued
2015-08-25 ’602 Patent Issued
2017-03-20 Plaintiff's predecessor allegedly notifies Defendant of patent portfolio
2024-07-12 First Amended Complaint Filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 6,957,369 - Hidden Failure Detection

The Invention Explained

  • Problem Addressed: The patent addresses the problem of detecting "hidden failures" in networking components that are idle. Such failures could go unnoticed until the component is needed, leading to service disruptions. Prior art testing methods were often intrusive, requiring systems to be taken offline, or utilized dedicated test hardware, which added cost and complexity (Compl. ¶¶16-17; ’369 Patent, col. 1:11-24).
  • The Patented Solution: The invention provides a method for non-intrusive self-testing that leverages existing system components. The system architecture, shown in the complaint at Figure 1, comprises a main module connected to multiple subsidiary modules via a backplane (Compl. p. 8, FIG. 1). The method involves selecting a first idle line to serve as an "aid line," instructing the connected subsidiary module to loop back traffic, then selecting a second idle line for testing. A switch on the main module links the two lines, and test traffic is sent from the second subsidiary module. A failure is reported if the test traffic does not return, indicating a fault in the tested line or its associated components (’369 Patent, col. 2:6-24, Abstract).
  • Technical Importance: This approach enabled automated, non-intrusive testing of idle network paths, improving the reliability of carrier-grade systems without requiring system downtime or additional hardware resources (Compl. ¶17).

Key Claims at a Glance

  • The complaint asserts independent claims 1 (method), 15 (apparatus), and 21 (apparatus), as well as dependent claims 2 and 18 (Compl. ¶¶15, 18, 24, 26).
  • Independent Claim 1 (Method) essential elements:
    • In an electronic system with a main module and at least first and second subsidiary modules connected by lines (some sometimes idle), and a switch on the main module, a method for self-testing comprising:
    • selecting a first idle line connecting the first subsidiary module to serve as an aid line;
    • instructing the first subsidiary module to loop back traffic via the aid line;
    • selecting for testing a second idle line connecting the second subsidiary module;
    • configuring the switch to link the first and second ports;
    • transmitting test traffic over the second idle line, which is conveyed via the switch to the aid line; and
    • reporting a failure if the test traffic does not return within a predetermined time.
  • Independent Claim 15 (Apparatus) essential elements:
    • A modular electronic apparatus comprising a backplane, a main module with a switch, at least first and second subsidiary modules, and a system control processor.
    • The processor is operative to perform the sequence of steps recited in method claim 1: select an idle trace as an aid trace, instruct loop back, select a second idle trace for testing, configure the switch to link them, cause test traffic to be transmitted, and report failure.
  • Independent Claim 21 (Apparatus) essential elements:
    • A modular electronic apparatus with a backplane, main module, and a plurality of subsidiary modules.
    • A system control processor operative to select first and second subsidiary modules of different types for testing, where the modules are configured to transmit/receive in different formats.
    • The processor tests the modules by causing the first to loop back traffic, configuring the main module to connect the two, and causing the second to transmit test traffic to the first, then assessing if the traffic returns intact.

U.S. Patent No. 7,113,485 - Latency Evaluation in a Ring Network

The Invention Explained

  • Problem Addressed: The patent seeks to provide accurate methods for measuring network latency, particularly round-trip latency between nodes in a ring network, without requiring costly and complex network-wide clock synchronization (’485 Patent, col. 2:35-55).
  • The Patented Solution: The invention proposes an apparatus and method where a node generates a "latency measurement packet" that includes an indication of its class of service (CoS), ensuring it is treated with the appropriate priority in the network. The system architecture, depicted in the complaint as a ring of nodes N1-N6, facilitates this measurement (Compl. p. 23, FIG. 1). To measure round-trip latency without synchronized clocks, a source node sends the packet; the destination (peer) node records its own local processing or "turnaround" time in the packet before sending it back. The source node can then calculate the net transit time by subtracting this turnaround time from the total trip time it measures locally (’485 Patent, col. 3:30-54).
  • Technical Importance: This invention provided a "simple and effective" way to measure latency for different classes of service, which is critical for network operators needing to verify performance against Service Level Agreements (SLAs) (Compl. ¶39; ’485 Patent, col. 2:65-67).

Key Claims at a Glance

  • The complaint asserts at least apparatus claim 16 (Compl. ¶¶40, 84).
  • Independent Claim 16 (Apparatus) essential elements:
    • An apparatus for measuring latency in a network with traffic transmitted in a plurality of classes of service.
    • The apparatus comprises a node which generates a latency measurement packet containing an indication that it belongs to a selected class of service.
    • The node transmits the packet so it is passed through the network at a level of service accorded to that class.
    • The node notes a time of receipt of the packet at a destination.
    • The node calculates the latency for the selected class by taking a difference between the time of transmission and the time of receipt.

U.S. Patent No. 7,330,431 - MULTIPOINT TO MULTIPOINT COMMUNICATION OVER RING TOPOLOGIES

  • Patent Identification: U.S. Patent No. 7,330,431, "MULTIPOINT TO MULTIPOINT COMMUNICATION OVER RING TOPOLOGIES," issued February 12, 2008 (Compl. ¶43).
  • Technology Synopsis: The patent describes a method for optimizing network bandwidth by distinguishing between a network's physical topology and the logical connections required by a specific service. A controller receives the definition of the logical connections, determines their bandwidth requirements, and maps them onto the physical links to allocate bandwidth more efficiently than simply reserving capacity for all possible paths (Compl. ¶45; ’431 Patent, Abstract).
  • Asserted Claims: The complaint specifies at least independent apparatus claim 25 (Compl. ¶46).
  • Accused Features: Cisco's "Collaboration Platform" Compatible Products, such as the Cisco BE7000 (Compl. ¶63).

U.S. Patent No. 7,593,400 - MAC ADDRESS LEARNING IN A DISTRIBUTED BRIDGE

  • Patent Identification: U.S. Patent No. 7,593,400, "MAC ADDRESS LEARNING IN A DISTRIBUTED BRIDGE," issued September 22, 2009 (Compl. ¶49).
  • Technology Synopsis: The patent discloses improved methods for Media Access Control (MAC) address learning in a distributed bridge, particularly in systems using Virtual Private LAN Services (VPLS) and Link Aggregation (LAG) groups. The invention uses per-line-card forwarding databases (FDBs) and requires a line card that learns a new MAC address association to send a synchronization message to other member line cards to update their FDBs, preventing unnecessary traffic flooding (Compl. ¶¶51-52; ’400 Patent, Abstract).
  • Asserted Claims: The complaint specifies at least independent method claim 1 (Compl. ¶52).
  • Accused Features: Cisco ASR 9000 series routers (Compl. ¶63).

U.S. Patent No. 9,118,602 - TUNNEL PROVISIONING WITH LINK AGGREGATION

  • Patent Identification: U.S. Patent No. 9,118,602, "TUNNEL PROVISIONING WITH LINK AGGREGATION," issued August 25, 2015 (Compl. ¶55).
  • Technology Synopsis: The patent addresses performing link aggregation within tunneled networks like Multi-Protocol Label Switching (MPLS). The method involves assigning a single physical port from a LAG to a network tunnel and dedicating a sub-set of bits in the packet's MPLS label to encode the serial number of that specific port. This allows downstream switches to route the packet to the correct physical port while maintaining bandwidth guarantees for the tunnel (Compl. ¶¶57-59; ’602 Patent, Abstract).
  • Asserted Claims: The complaint specifies at least independent method claim 1 (Compl. ¶59).
  • Accused Features: Cisco Nexus 9000 Series Switches (Compl. ¶63).

III. The Accused Instrumentality

Product Identification

  • The complaint identifies three categories of accused products: the Cisco ASR 9000 series routers, the Cisco Nexus 9000 Series Switches, and Cisco's "Collaboration Platform" Compatible Products (e.g., Cisco BE7000) (Compl. ¶63).

Functionality and Market Context

  • The Accused Products are networking hardware, specifically routers and switches, that form the basis of modern telecommunications and data center networks (Compl. ¶62). The complaint alleges these products implement the patented technologies. For example, it alleges the Nexus 9000 Switches practice the hidden failure detection of the ’369 patent and the tunnel provisioning of the ’602 patent. It alleges the ASR 9000 routers practice the latency evaluation of the ’485 patent and the MAC learning of the ’400 patent. Finally, it alleges the Collaboration Platform products practice the bandwidth allocation methods of the ’431 patent (Compl. ¶63). The complaint references Cisco’s own datasheets and configuration guides as evidence of the products' functionality and promotion (Compl. ¶65, Ex. 11-15).

IV. Analysis of Infringement Allegations

The complaint’s detailed infringement theory is contained in external exhibits (e.g., Ex. 6, 8, 10) which are incorporated by reference but not attached to the pleading (Compl. ¶65, ¶74). The complaint states that these exhibits provide a comparison of the asserted claims to the Accused Products. Without access to these exhibits, a detailed element-by-element analysis of the alleged infringing functionality is not possible from the complaint's text alone.

The general infringement theory posits that the Accused Products practice the patented technologies to achieve improved network performance, reliability, and efficiency. The complaint alleges that Defendant’s own marketing materials, data sheets, and technical guides for the Accused Products describe and promote the use of the subject matter claimed in the Asserted Patents (Compl. ¶¶65, 76). For example, the complaint references a "Segment Routing Configuration Guide for Cisco ASR 9000 Series Routers" and a datasheet for "Cisco Nexus 9500 Series Switches" as part of its infringement allegations (Compl. ¶65). The narrative theory for each patent is that the corresponding accused product directly infringes the asserted claims by making, using, or selling hardware and software that implement the claimed methods and apparatuses (Compl. ¶¶74, 84, 94, 104, 114).

  • Identified Points of Contention:
    • ’369 Patent: A primary technical question will concern whether the diagnostic functionalities of the Cisco Nexus 9000 switches operate according to the specific sequence claimed: selecting a dedicated "aid line" from a pool of "idle lines," instructing a loopback on that line, and then using it to test another selected idle line. The complaint's detailed arguments distinguishing the invention from prior art suggest that the precise sequence and architecture will be a focus of the dispute (Compl. ¶¶19-21).
    • ’485 Patent: The primary legal issue for this patent is its eligibility under 35 U.S.C. § 101, given the complaint’s acknowledgment of a prior adverse ruling in the case (Compl. p. 22, fn. 2). A technical question will be whether the Cisco ASR 9000’s latency measurement tools generate a specific "latency measurement packet" tied to a "class of service" and calculate latency as required by claim 16, or if they employ a functionally different method.

V. Key Claim Terms for Construction

U.S. Patent No. 6,957,369

  • The Term: "idle line" / "idle trace" (Claim 1, 15)
  • Context and Importance: The invention is premised on the non-intrusive testing of "idle" components. The definition of this term is critical for infringement, as it will determine which lines within the accused switches are subject to the claimed testing method. Practitioners may focus on this term because its scope—whether it means a line completely devoid of any signaling, or merely a line not carrying active user data—will dictate whether the accused products' testable lines meet this limitation.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The body of claim 1 simply refers to lines that are "sometimes idle," without further qualification, which may support a broad, ordinary meaning (’369 Patent, col. 7:6-7).
    • Evidence for a Narrower Interpretation: The background section frames the goal as testing "without interrupting normal operation of active components," which could support a narrower construction where "idle" means not carrying any revenue-generating or user-facing service traffic, even if control or maintenance signals are present (’369 Patent, col. 1:23-24).

U.S. Patent No. 7,113,485

  • The Term: "latency measurement packet" (Claim 16)
  • Context and Importance: This term defines the vehicle for the patented measurement technique. Its construction is central to determining whether the packets used by the accused routers for performance monitoring fall within the scope of the claims. The dispute may turn on whether any packet used for timing constitutes a "latency measurement packet" or if it must possess the specific characteristics described in the patent.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: Claim 16 itself only requires the packet to contain "an indication that the packet belongs to a selected one of the classes of service," suggesting any such packet could qualify (’485 Patent, col. 8:26-29).
    • Evidence for a Narrower Interpretation: The detailed description provides a specific structure for an "LMP" in Table I, including fields for "Loopback (LE)" and "Serial number (SN)," which a party could argue are defining characteristics of the claimed packet, even if not explicitly recited in claim 16 (’485 Patent, col. 7:20-40).

VI. Other Allegations

  • Indirect Infringement: For all asserted patents, the complaint alleges induced infringement under 35 U.S.C. § 271(b). The allegations are based on Defendant’s creation and distribution of product documentation, including data sheets, manuals, and configuration guides, which allegedly instruct and encourage customers and end-users to operate the Accused Products in an infringing manner (Compl. ¶¶75-76, 85-86, 95-96, 105-106, 115-116).
  • Willful Infringement: The complaint alleges that Defendant’s infringement has been and continues to be willful. The basis for this allegation is Defendant's alleged pre-suit knowledge of the patents, dating back to communications initiated in March 2017 by Plaintiff's predecessor-in-interest, Orckit IP, regarding its patent portfolio and its relevance to Cisco's products (Compl. ¶¶66-71, 79, 89, 99, 109, 119).

VII. Analyst’s Conclusion: Key Questions for the Case

  1. Validity and Patent Eligibility: A central battleground will be the validity of the asserted patents. For the ’369 patent, a key question is whether Cisco can present a prior art case sufficient to invalidate the claims despite the PTAB’s prior denials of IPR institution. For the ’485 patent, the threshold question is one of patent eligibility: can Corrigent persuade the court to reverse its earlier finding that the patent is directed to an abstract idea under 35 U.S.C. § 101?
  2. Evidence of Infringing Operation: As the complaint relies on external, non-public exhibits for its technical infringement proof, a key evidentiary question will be one of functional correspondence: does discovery concerning the accused products' actual operation reveal that they perform the specific, multi-step processes and employ the particular apparatus configurations recited in the claims, or will it expose a fundamental mismatch in technical operation?
  3. Claim Scope and Pre-Suit Knowledge: The outcome will likely depend on claim construction and willfulness. A core issue will be one of definitional scope: can terms like "idle line" ('369 patent) and "latency measurement packet" ('485 patent) be construed to read on the features of the accused products? Furthermore, a critical factual question for willfulness will be the nature and content of the alleged 2017-2018 pre-suit communications and what level of knowledge they imparted to Cisco.