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., 04/19/2022
  • Venue Allegations: Plaintiff alleges venue is proper because Defendant has committed acts of infringement and has a regular and established place of business in the Western District of Texas.
  • Core Dispute: Plaintiff alleges that Defendant’s enterprise-grade network routers and switches infringe five patents related to telecommunications network management, including failure detection, latency evaluation, bandwidth allocation, and MAC address learning.
  • Technical Context: The patents address technologies for improving the reliability, performance, and efficiency of large-scale packet-switched networks, such as those using Ethernet and Multi-Protocol Label Switching (MPLS).
  • Key Procedural History: The complaint alleges that a prior owner of the asserted patents, Orckit IP LLC, engaged in licensing discussions with Cisco beginning in March 2017, providing notice of the patents and accused products. Subsequent Inter Partes Review (IPR) proceedings have resulted in the cancellation of all claims of the ’485 Patent and the cancellation of asserted claim 25 of the ’431 Patent. Claims of the ’602 Patent were found patentable in a separate IPR.

Case Timeline

Date Event
2001-09-04 Earliest Priority Date for ’485 Patent
2002-05-30 Earliest Priority Date for ’369 Patent
2004-09-03 Earliest Priority Date for ’431 Patent
2005-05-06 Earliest Priority Date for ’602 Patent
2005-10-18 ’369 Patent Issued
2006-05-19 Earliest Priority Date for ’400 Patent
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 Orckit IP (prior patent owner) sends letter to Cisco
2017-04-10 Cisco responds to Orckit IP
2018-07-11 Orckit IP sends second notice letter to Cisco
2018-11-20 Orckit IP identifies ’485 Patent in email to Cisco
2022-04-19 Complaint Filed
2022-11-17 IPR filed against ’485 Patent (IPR2023-00168)
2022-11-17 IPR filed against ’431 Patent (IPR2023-00169)
2023-01-10 IPR filed against ’602 Patent (IPR2023-00447)
2024-09-25 IPR Certificate issues cancelling asserted ’431 claim 25
2024-10-18 IPR Certificate issues cancelling all claims of ’485 Patent
2025-03-11 IPR Certificate issues confirming patentability of ’602 claims

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

U.S. Patent No. 6,957,369 - Hidden Failure Detection, issued October 18, 2005

The Invention Explained

  • Problem Addressed: The patent addresses "hidden failures" in electronic systems, where idle components or data lines fail but the failure goes undetected until the component is activated for service, causing an outage at a critical time (’369 Patent, col. 1:11-24).
  • The Patented Solution: The invention provides a method for non-intrusive self-testing of communication systems that uses existing hardware (’369 Patent, col. 2:29-32). As depicted in a block diagram of a modular electronic apparatus (Compl. p. 6), the system selects an idle data path to serve as a temporary "aid trace" and instructs the connected subsidiary module to loop back any traffic it receives on that trace (’369 Patent, col. 2:6-9). The system then tests another idle trace by configuring a switch to link it to the aid trace, sending test traffic down the test trace. A failure is reported if the test traffic is not looped back and returned to its origin within a predetermined time, allowing for proactive detection of faults without disrupting active services (’369 Patent, Abstract).
  • Technical Importance: This approach allows for enhanced system reliability and proactive maintenance in complex, modular network equipment without the cost and complexity of dedicated testing hardware (’369 Patent, col. 1:20-24).

Key Claims at a Glance

  • The complaint asserts independent claim 15 (Compl. ¶57).
  • Essential elements of claim 15 include:
    • A modular apparatus with a backplane, a main module containing a switch, and at least first and second subsidiary modules.
    • A system control processor operative to select a first idle trace connecting the first subsidiary module to serve as an "aid trace."
    • The processor instructs the first subsidiary module to "loop back traffic" reaching it via the aid trace.
    • The processor selects a second idle trace for testing and configures the switch to link the test trace to the aid trace.
    • The processor causes test traffic to be transmitted over the test trace, conveyed via the switch to the aid trace, and reports a failure if the traffic does not return to the second subsidiary module.

U.S. Patent No. 7,113,485 - Latency Evaluation in a Ring Network, issued September 26, 2006

The Invention Explained

  • Problem Addressed: The patent seeks to solve the difficulty of accurately measuring round-trip, node-to-node latency in networks, particularly ring topologies, which traditionally required costly and precisely synchronized clocks at all nodes (’485 Patent, col. 2:41-55).
  • The Patented Solution: The invention proposes a method using a special "latency measurement packet" (LMP) that can be generated for a specific "class of service" (CoS) to measure latency for different traffic priorities (’485 Patent, Abstract; col. 3:23-29). As illustrated in a diagram of nodes in a ring network (Compl. p. 8), an originating node sends the LMP to a peer node. The peer node records its own reception and transmission times within the packet using its own unsynchronized clock before returning the packet. This allows the originating node to calculate the net round-trip latency by subtracting the peer's measured turnaround time from the total travel time, eliminating any dependency on clock synchronization between the nodes (’485 Patent, col. 3:29-54).
  • Technical Importance: This method provides a simple and accurate way to monitor network performance and verify compliance with Service Level Agreements (SLAs) for different classes of service without requiring expensive, synchronized hardware across the network (’485 Patent, col. 2:56-67).

Key Claims at a Glance

  • The complaint asserts independent claim 16 (Compl. ¶67).
  • Essential elements of claim 16 include:
    • An apparatus (a node) for measuring latency in a network with multiple classes of service.
    • The node generates a "latency measurement packet" that includes an indication of which class of service it belongs to.
    • The node transmits the packet so it is handled with the priority of that class.
    • The node notes a time of receipt at a destination.
    • The node calculates the latency for the selected class of service by taking a difference between the transmission time and receipt time.

U.S. Patent No. 7,330,431 - Multipoint to Multipoint Communication Over Ring Topologies, issued February 12, 2008

  • Technology Synopsis: The patent addresses the problem of optimizing bandwidth allocation in a network. It describes a method where a controller receives a definition of logical connections for a service (which may differ from the physical network topology), determines the bandwidth requirements for those logical connections, and then maps the logical topology to the physical topology to efficiently allocate bandwidth on each physical link (Compl. ¶28; ’431 Patent, Abstract).
  • Asserted Claims: The complaint asserts independent claim 25 (Compl. ¶77).
  • Accused Features: The complaint accuses Cisco's "Collaboration Platform" Compatible Products, such as the Cisco BE7000 (Compl. ¶46).

U.S. Patent No. 7,593,400 - MAC Address Learning in a Distributed Bridge, issued September 22, 2009

  • Technology Synopsis: The patent discloses improved methods for Media Access Control (MAC) address learning in distributed network bridges, particularly those using Link Aggregation (LAG) groups. When one line card in a distributed node learns a new MAC address association from an incoming packet, it creates a record in its forwarding database (FDB) and sends a message to the other member line cards of the LAG, allowing them to synchronize their own FDBs without having to see the traffic themselves (Compl. ¶34; ’400 Patent, Claim 1).
  • Asserted Claims: The complaint asserts independent claim 1 (Compl. ¶87).
  • Accused Features: The complaint accuses the Cisco ASR 9000 series of routers (Compl. ¶46).

U.S. Patent No. 9,118,602 - Tunnel Provisioning with Link Aggregation, issued August 25, 2015

  • Technology Synopsis: The patent describes a method for provisioning network tunnels (e.g., in an MPLS network) that traverse a Link Aggregation (LAG) group. The method involves assigning a single physical port from the LAG to the tunnel to meet its bandwidth requirements and then dedicating a sub-set of bits in the data packet's label to encode the serial number of that specific physical port, ensuring traffic is routed correctly and service guarantees are met (Compl. ¶¶ 41, 42).
  • Asserted Claims: The complaint asserts independent claim 1 (Compl. ¶97).
  • Accused Features: The complaint accuses the Cisco Nexus 9000 Series Switches (Compl. ¶46).

III. The Accused Instrumentality

Product Identification

The complaint identifies three categories of accused products: Cisco Nexus 9000 Series Switches, Cisco ASR 9000 Series Aggregation Services Routers, and Cisco's "Collaboration Platform" Compatible Products (e.g., Cisco BE7000) (Compl. ¶46).

Functionality and Market Context

These products are high-performance networking hardware for data center, enterprise, and service provider environments (Compl. ¶45). The complaint alleges these products incorporate infringing technologies for system diagnostics, performance monitoring, bandwidth management for collaboration services, and traffic handling in distributed and aggregated link environments (Compl. ¶¶ 46-48). The complaint cites various Cisco technical documents, including data sheets and configuration guides, as containing descriptions of the allegedly infringing functionality (Compl. ¶48).

IV. Analysis of Infringement Allegations

The complaint incorporates by reference external claim chart exhibits that were not included in the provided filing; therefore, a tabular analysis is not possible. The narrative infringement theories are summarized below.

  • ’369 Patent Infringement Allegations: The complaint alleges that the Cisco Nexus 9000 Series Switches infringe at least claim 15 of the ’369 patent (Compl. ¶57). The infringement theory appears to target diagnostic or self-testing features within the Nexus switches. The central dispute may focus on whether these features operate by selecting an "aid trace" and instructing a module to "loop back traffic" in the specific manner required by the claim.
  • ’485 Patent Infringement Allegations: The complaint alleges that the Cisco ASR 9000 series routers infringe at least claim 16 of the ’485 patent (Compl. ¶67). The infringement theory likely relates to performance monitoring capabilities, such as Cisco’s IP SLA features. A potential point of contention is whether the packets used by these features constitute a "latency measurement packet" for a specific "class of service" as defined by the patent.
  • Identified Points of Contention:
    • Scope Questions: A recurring question across the patents will be whether Cisco’s implementation of industry-standard or proprietary features (e.g., diagnostics, SLA monitoring, MAC learning) falls within the specific boundaries of the patent claims. For instance, does the term "loop back traffic" in the ’369 patent, which the specification suggests is a bit-by-bit return (’369 Patent, col. 2:9-12), read on the potentially more complex packet forwarding or re-routing that may occur in the accused switches?
    • Technical Questions: A key evidentiary challenge for the plaintiff will be to demonstrate that the accused products perform the claimed functions. For the ’485 patent, what evidence does the complaint provide that the accused ASR 9000 routers generate a packet specifically for measuring latency for a selected class of service and that the network handles that packet according to the priority of that class, as required by claim 16?

V. Key Claim Terms for Construction

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

  • The Term: "loop back traffic" (from Claim 15)
  • Context and Importance: The definition of this term is critical for determining whether the accused Nexus switches perform the claimed testing method. Practitioners may focus on this term because its construction will determine whether a simple physical-layer loopback is required, or if a higher-level packet forwarding function can infringe.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The claim language itself does not specify the OSI layer at which the "loop back" must occur, potentially allowing for an interpretation that covers any function that returns traffic.
    • Evidence for a Narrower Interpretation: The specification states that the loopback function "does not require that the subsidiary module decode or process the traffic—only that it send it back bit by bit" (’369 Patent, col. 2:9-12). This language could be used to argue for a narrower construction limited to a physical-layer or bit-level operation.

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

  • The Term: "latency measurement packet" (from Claim 16)
  • Context and Importance: The infringement analysis for the ASR 9000 routers will likely depend on whether their standard monitoring packets (e.g., IP SLA or ICMP packets) meet the definition of this term. The dispute will center on whether the term requires a specialized packet structure or merely a functional purpose.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The claim functionally defines the packet as one "containing an indication that the packet belongs to a selected one of the classes of service" and is used to calculate latency. Any packet that serves this function could arguably be covered.
    • Evidence for a Narrower Interpretation: The specification discloses an exemplary LMP format in Table I with specific fields such as "Txtg," "Rxtg," "Txtp," and "Rxtp" (’485 Patent, col. 7). A party could argue that an accused packet must contain these specific fields or their clear equivalents to be considered a "latency measurement packet."

VI. Other Allegations

  • Indirect Infringement: For all asserted patents, the complaint alleges induced infringement, stating that Defendant’s data sheets, manuals, and guides instruct customers and end-users on how to use the accused products in an infringing manner (e.g., Compl. ¶¶ 58-59). The complaint also pleads contributory infringement, alleging the accused products are especially made for an infringing use and are not staple articles of commerce (e.g., Compl. ¶ 60).
  • Willful Infringement: Willfulness is alleged for all asserted patents. The allegations are based on pre-suit notice allegedly provided by a prior owner of the patents, Orckit IP, to Cisco starting in March 2017. The complaint states that Orckit IP identified the patent portfolio, the accused products, and offered to provide "evidence of use charts" (Compl. ¶¶ 49, 54, 62).

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

  • A central issue will be one of claim viability: Can the plaintiff proceed with its claims for infringement of the ’485 and ’431 patents, given that subsequent IPR proceedings resulted in the cancellation of all claims of the ’485 patent and the specifically asserted claim 25 of the ’431 patent?
  • A key evidentiary question will be one of functional equivalence: For the remaining patents, does the operation of Cisco’s accused routers and switches map onto the specific, and in some cases multi-step, technical processes required by the claims (e.g., the '369 patent's "aid trace" loopback or the '400 patent's FDB synchronization message), or is there a fundamental mismatch in their technical operation?
  • A significant factual question will relate to willfulness: Did the alleged pre-suit communications from the prior patent owner provide Cisco with knowledge of infringement that was sufficiently clear to render its continued conduct objectively reckless, thereby supporting a claim for enhanced damages?