DCT

2:26-cv-00788

Portsmouth Network Corp v. Cisco Systems Inc

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 2:26-cv-00788, E.D. Tex., Marshall Division, 09/03/2026
  • Venue Allegations: Venue is based on Defendant maintaining regular and established places of business within the Eastern District of Texas, specifically in Richardson and Allen, and allegedly committing acts of infringement in the district.
  • Core Dispute: Plaintiff alleges that Defendant’s enterprise-grade routers and switches infringe six U.S. patents related to Ethernet network performance, reliability, and security.
  • Technical Context: The technology at issue addresses challenges in carrier-grade Ethernet networking, including efficient resource allocation, network security against denial-of-service attacks, and high-availability mechanisms.
  • Key Procedural History: The complaint alleges that a prior owner of the patents, Orckit IP, first contacted Defendant in March 2017 to discuss the patent portfolio and its relevance to Defendant's products, with further correspondence occurring in 2018. The complaint also references a prior lawsuit between the same parties filed on September 26, 2023, which may be significant for establishing pre-suit knowledge for willfulness allegations. The record also reflects PTAB proceedings on asserted patents: in IPR2024-00503, the Board issued a Final Written Decision determining that no challenged claims of the '279 patent are unpatentable, and in IPR2024-00954, the Board denied institution of inter partes review of the '637 patent. The complaint further pleads infringement under 35 U.S.C. § 271(a), (b), and (c); statutory bases for subject-matter jurisdiction, personal jurisdiction, and venue; ownership and standing by assignment; compliance with the 35 U.S.C. § 287 marking requirement; a demand for a jury trial; and a prayer for relief including a permanent injunction, treble damages under 35 U.S.C. § 284, and attorneys' fees under 35 U.S.C. § 285. Plaintiff is represented by local and of-counsel Miller Fair Henry PLLC.

Case Timeline

Date Event
2001-01-09 U.S. Patent No. 7,035,279 Priority Date
2002-02-01 U.S. Patent No. 7,154,899 and 7,773,508 Priority Date
2003-03-12 U.S. Patent No. 7,420,922 Priority Date
2005-01-01 KDDI deploys Corrigent-Systems products "as early as 2005"
2005-11-16 U.S. Patent No. 8,199,637 Priority Date
2006-04-25 U.S. Patent No. 7,035,279 Issued
2006-11-09 U.S. Patent No. 7,773,508 Filing Date
2006-11-13 U.S. Patent No. 7,626,930 Priority Date
2006-12-26 U.S. Patent No. 7,154,899 Issued
2008-09-02 U.S. Patent No. 7,420,922 Issued
2009-12-01 U.S. Patent No. 7,626,930 Issued
2010-08-10 U.S. Patent No. 7,773,508 Issued
2012-06-12 U.S. Patent No. 8,199,637 Issued
2017-03-20 Orckit IP sends first letter to Cisco regarding patent portfolio
2017-04-10 Cisco responds to Orckit IP's letter
2018-07-11 Orckit IP sends second letter to Cisco
2018-07-25 Cisco responds to second letter
2018-11-20 Orckit IP identifies '637 patent in communications with Cisco
2023-09-26 Prior lawsuit filed by Plaintiff against Defendant
2026-09-03 Complaint Filing Date

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

U.S. Patent No. 7,035,279 - “Flow allocation in a ring topology,” Issued April 25, 2006

The Invention Explained

  • Problem Addressed: The patent’s background describes that existing ring network protocols, such as the Spatial Reuse Protocol (SRP), allowed nodes to choose between an inner and outer ring for sending data but did not provide a dynamic method for making that choice based on network conditions (ʼ279 Patent, col. 1). Protocols like OSPF used static "costs," which do not adapt to real-time network resource constraints ʼ279 Patent, col. 1
  • The Patented Solution: The invention proposes a centralized "dispatcher" that learns the network topology and tracks resource usage ʼ279 Patent, col. 2:25-29 When a node requires resources to send a data flow, it first checks its own allocation; if insufficient, it requests resources from the dispatcher, which then analyzes usage levels on the network paths and allocates resources on the optimal path (inner or outer ring) ʼ279 Patent, abstract ʼ279 Patent, col. 2:29-36 An embodiment is shown in FIG. 3 of the patent, which the complaint reproduces as a flowchart illustrating a method for assigning network resources Compl. ¶18 Compl. p. 6
  • Technical Importance: The invention provided a method for dynamic, load-aware routing in ring topologies, improving efficiency over static routing protocols Compl. ¶18

Key Claims at a Glance

  • The complaint asserts independent claim 1 Compl. ¶19 Compl. ¶65
  • Essential elements of claim 1 include:
    • Allocating a number of "quanta" of resources to network nodes.
    • Receiving a request at a first node to use resources for a data flow to a second node.
    • If resources are sufficient, directing the data flow without requesting more.
    • If resources are insufficient: requesting an increase in allocation; determining resource use levels on the available paths; selecting a path responsive to those use levels; and increasing the resource allocation on the selected path.
  • The complaint does not explicitly reserve the right to assert dependent claims but makes a general claim for "one or more claims" Compl. ¶65

U.S. Patent No. 7,154,899 - “Protecting the filtering database in virtual bridges,” Issued December 26, 2006

The Invention Explained

  • Problem Addressed: The patent addresses the vulnerability of filtering databases in virtual bridges to Denial-of-Service (DOS) attacks (ʼ899 Patent, col. 4:7-9). An attacker could flood a bridge with packets from bogus source addresses, forcing the learning process to fill the database with useless entries and discard legitimate ones, leading to network overload ʼ899 Patent, col. 3
  • The Patented Solution: The invention introduces "budgeted learning," where each communication domain (e.g., a VLAN) is given a limited "budget" of new entries it can add to the shared database during a "learning period" ʼ899 Patent, col. 4:14-22 Once the budget is exhausted, the bridge discards further frames with unknown source MAC addresses from that domain, thereby protecting the database from being overloaded ʼ899 Patent, col. 4:22-29 The complaint includes the patent's FIG. 2, a flowchart illustrating this method for limiting the learning process Compl. ¶24 Compl. p. 8
  • Technical Importance: This technology provided a defense mechanism for critical network infrastructure against a common type of DOS attack, enhancing network stability and reliability Compl. ¶24

Key Claims at a Glance

  • The complaint asserts independent claim 1 Compl. ¶25 Compl. ¶75
  • Essential elements of claim 1 include:
    • Providing a database for link information.
    • Setting a maximum rate for adding entries to the database.
    • Determining a new entry to add based on network traffic during a learning period.
    • Adding the new entry only if the maximum rate has not been exceeded.
    • Wherein setting the maximum rate comprises setting a "budget" of entries, and adding the new entry comprises "decrementing the budget."
  • The complaint does not explicitly reserve the right to assert dependent claims but makes a general claim for "one or more claims" Compl. ¶75

U.S. Patent No. 7,420,922 - “Ring Network With Variable Rate,” Issued September 2, 2008

  • Technology Synopsis: The patent addresses the problem of changing the data rate of an entire ring network without causing service disruption Compl. ¶30 The invention describes a synchronized method where a "manager node" first validates that all other nodes can perform the rate change, then sends a command to execute the change substantially simultaneously across the network, minimizing the time that different segments operate at mismatched rates Compl. ¶31 '922 Patent, col. 2:41-57
  • Asserted Claims: The complaint asserts independent claim 1 Compl. ¶31 Compl. ¶85
  • Accused Features: The complaint alleges that the Cisco Catalyst 9000 Switches infringe the ’922 patent Compl. ¶53

U.S. Patent No. 7,626,930 - “Hash-based multi-homing,” Issued December 1, 2009

  • Technology Synopsis: The patent presents a method to provide communication redundancy and load balancing ("multi-homing") while preventing layer-2 loops Compl. ¶36 The solution defines a "multi-homing group" (MHG) of member ports residing in different network nodes that provide alternative paths. Each MHG node applies the same hashing function to frame headers to deterministically select a single path for forwarding, ensuring all nodes make the same decision and thereby preventing loops Compl. ¶36 '930 Patent, col. 4:11-19
  • Asserted Claims: The complaint asserts independent claim 1 Compl. ¶37 Compl. ¶95
  • Accused Features: The complaint alleges that the Cisco Catalyst 9000 Switches infringe the ’930 patent Compl. ¶53

U.S. Patent No. 7,773,508 - “Protecting the filtering database in virtual bridges,” Issued August 10, 2010

  • Technology Synopsis: This patent, related to the '899 patent, also aims to protect filtering databases from DOS attacks Compl. ¶42 It teaches a method of "budgeted learning" where a virtual bridge limits the rate at which new MAC addresses can be added to its database from any given communication domain (e.g., VLAN) during a set time period, preventing malicious actors from overwhelming the database (Compl. ¶42; '508 Patent, col. 4:14-32).
  • Asserted Claims: The complaint asserts independent claim 1 Compl. ¶43 Compl. ¶105
  • Accused Features: The complaint alleges that the Cisco Nexus 9000 Switches infringe the ’508 patent Compl. ¶53

U.S. Patent No. 8,199,637 - “VPLS remote failure indication,” Issued June 12, 2012

  • Technology Synopsis: This patent addresses slow recovery times from communication failures in networks providing services like VPLS (Virtual Private LAN Service) Compl. ¶48 The invention provides a method for rapid failure recovery where a node detecting a local failure in a primary link propagates this failure information to other nodes. The other nodes then deactivate the physical layer of their own links to the primary topology, causing a rapid loss of connectivity that forces higher-level protocols to switch to a backup topology Compl. ¶48 '637 Patent, col. 4:17-27
  • Asserted Claims: The complaint asserts independent claim 1 Compl. ¶49 Compl. ¶115
  • Accused Features: The complaint alleges that the Cisco ASR 9000 Series Routers and Cisco Catalyst 9000 Switches infringe the ’637 patent Compl. ¶53

III. The Accused Instrumentality

Product Identification

  • The accused products are the Cisco ASR 9000 Series Routers, Cisco Catalyst 9000 Switches, and Cisco Nexus 9000 Switches Compl. ¶53

Functionality and Market Context

  • The complaint identifies these products as networking hardware (routers and switches) that Defendant makes, uses, and sells in the United States Compl. ¶52 The complaint alleges these products implement features for network routing, switching, security, and high availability that correspond to the technologies claimed in the asserted patents Compl. ¶53 Compl. ¶56 The complaint specifically maps asserted patents to product families: for example, the Catalyst 9000 Switches are accused of infringing the '279, '922, '930, and '637 patents, while the Nexus 9000 Switches are accused of infringing the '899 and '508 patents Compl. ¶53

IV. Analysis of Infringement Allegations

The complaint references, but does not provide, claim chart exhibits detailing the infringement allegations for each patent Compl. ¶55 The narrative infringement theory presented in the complaint is summarized below for each lead patent.

  • '279 Patent Infringement Allegations
    The complaint alleges that the Accused Products, including the Cisco Catalyst 9000 Switches, infringe at least claim 1 of the '279 patent Compl. ¶65 Compl. ¶53 The narrative theory is that the accused switches perform a method for routing data flow in a communication network by allocating resources, receiving requests to use those resources, and selecting a path based on network use levels, as recited in claim 1 Compl. ¶19 The specific, element-by-element comparison of the accused product functionality to the claim language is incorporated by reference from an unprovided exhibit Compl. ¶65

  • '899 Patent Infringement Allegations
    The complaint alleges that the Accused Products, including the Cisco Nexus 9000 Switches, infringe at least claim 1 of the '899 patent Compl. ¶75 Compl. ¶53 The narrative theory is that the accused switches practice a method for "budgeted learning" of link information, which involves setting a maximum rate for adding entries to a database, determining new entries based on traffic, and adding them only if a "budget" has not been exceeded, as recited in claim 1 Compl. ¶25 The specific mapping of these claim elements to accused product features is incorporated by reference from an unprovided exhibit Compl. ¶75

  • Identified Points of Contention:

    • Architectural Questions: For the '279 patent, a key question may be whether the accused switches contain a centralized or distributed function that meets the claim requirement of a "dispatcher" which "allocates" resources and "selects" a path based on dynamic resource use levels, where the request to use resources is "received at the first node" rather than by the dispatcher. For the '899 and '508 patents, a central question may be whether the accused switches' mechanism for mitigating database-oriented DOS attacks operates on the specific "depletable "budget"" principle recited in the claims, or if it uses a technically distinct method of simple rate-limiting.
    • Functional Questions: For the '637 patent, a point of contention may arise over whether the accused products' high-availability mechanism operates by "deactivating a physical layer" to cause a "loss of connectivity," as required by the claim, or if it uses a different signaling method to trigger a failover to a backup path.

V. Key Claim Terms for Construction

  • Term: "dispatcher" (from '279 Patent, claim 1, implied)

    • Context and Importance: Practitioners may focus on this term because the existence of a "dispatcher" is a core architectural element of the '279 patent's invention. The infringement analysis for claim 1 will hinge on whether any component or set of processes within the accused switches can be characterized as performing the functions of the claimed "dispatcher".
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The specification notes that the dispatcher may be a "software process running on the [associated] node" ʼ279 Patent, col. 4:50-52, which might support an argument that the function can be distributed rather than a single, monolithic entity.
      • Evidence for a Narrower Interpretation: The specification and figures consistently depict the "dispatcher" as a distinct entity that "tracks the use of resources," from which other nodes "request" allocations, and which "processes the request and determines whether to allocate the resources" ʼ279 Patent, col. 2:25-36 '279 Patent, Fig. 3 This language suggests a centralized, command-and-control function that actively grants or denies resource requests.

  • Term: "budget" (from '899 Patent, claim 1)

    • Context and Importance: Practitioners may focus on this term because the claim explicitly requires "setting a budget" and "decrementing the budget." This is technically distinct from a simple rate limit. The dispute may turn on whether the accused products' mechanism for controlling MAC address learning functions as a depletable "budget" or as a different type of rate-limiting governor.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The patent's summary states the goal is to limit the "rate of the learning process" ʼ899 Patent, col. 4:18-19 This could support an argument for a broader construction, although claim 1 expressly requires setting a budget and decrementing it when adding an entry, which constrains how broadly that stated goal can be read.
      • Evidence for a Narrower Interpretation: The claim language is highly specific, requiring not just a rate limit but "setting a budget" and "decrementing the budget" when adding an entry, with claim 1 permitting a new entry only if the maximum rate has "not exceeded" ʼ899 Patent, claim 1, while the "budget [is] exhausted" check appears in the patent's flowchart '899 Patent, Fig. 2 This points toward a specific implementation of a counter that is consumed and periodically replenished, rather than a generic rate limit.

VI. Other Allegations

  • Relief Sought and Jury Demand: The complaint includes a demand for a jury trial on all triable issues and a prayer for relief seeking a permanent injunction, treble damages under 35 U.S.C. § 284, attorneys' fees under 35 U.S.C. § 285 for an exceptional case, costs, and pre- and post-judgment interest, and alleges compliance with the 35 U.S.C. § 287 marking requirement.

  • Indirect Infringement: For all asserted patents, the complaint alleges both induced and contributory infringement. The allegations are based on Defendant's marketing materials, data sheets, and user guides, which allegedly instruct and encourage customers to use the Accused Products in an infringing manner (e.g., Compl. ¶¶66-67). The complaint further alleges the Accused Products are "especially made or especially adapted" for infringement and are not staple articles of commerce (e.g., Compl. ¶68).

  • Willful Infringement: The complaint alleges willful infringement for all asserted patents. The basis for willfulness is alleged pre-suit knowledge stemming from a series of communications initiated in March 2017 by Orckit IP, a prior owner of the patents. For certain patents (e.g., the '279 and '637 patents), the complaint additionally pleads knowledge from a prior lawsuit filed in 2023, while for other patents (e.g., the '899 patent) the knowledge allegation rests on the March 2017 communications and the filing of this Complaint (e.g., Compl. ¶¶57-62; Compl. ¶70).

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

  • Architectural Equivalence: A core issue will be one of architectural and functional equivalence. Does the routing functionality in Defendant's switches perform the same function in substantially the same way as the '279 patent's centralized "dispatcher"? Similarly, do the security features in Defendant's products operate on the specific "depletable "budget"" principle of the '899 and '508 patents, or do they employ a technically distinct mechanism?
  • Claim Scope and Construction: The scope of the infringement allegations will depend heavily on claim construction. The case may turn on whether terms like "dispatcher" and "budget" are given a broad, functional interpretation or are limited to the specific embodiments described in the patents, such as a centralized entity that grants requests or a counter that is explicitly decremented.
  • Willfulness and Damages: A central evidentiary question will be the extent of Defendant's knowledge. The complaint details specific pre-suit communications and a prior lawsuit. The court will likely examine whether this history supports a finding that Defendant's infringement was subjectively willful, deliberate, or egregious, which would be critical for the determination of willful infringement and potential enhanced damages.