PTAB

IPR2022-00238

F5 Networks Inc v. WSOU Investments LLC

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Key Events
Petition

1. Case Identification

2. Patent Overview

  • Title: Active Load Balancing Using Clustered Nodes
  • Brief Description: The ’945 patent discloses systems and methods for active load balancing of Domain Name Service (DNS) queries. The technology uses a plurality of network devices in a cluster, where one device is designated as a "master device" that functions as an authoritative name server, receives status information from the other devices, and selects a device to handle a client request based on that status information.

3. Grounds for Unpatentability

Ground 1: Claims 1-17 are anticipated and/or obvious over Gourley

  • Prior Art Relied Upon: Gourley (“HTTP: The Definitive Guide,” a 2002 textbook).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Gourley, a foundational text on web protocols, discloses every element of the challenged claims. Specifically, Gourley’s discussion of DNS-based load balancing and its Figure 20-4 depict an "Authoritative DNS server" that actively "monitors" a collection of web servers for load status. This authoritative server (the master device) receives DNS queries and returns the IP address of the least-loaded web server from the monitored collection (the cluster) to a client. Petitioner contended this maps directly to the independent claims’ requirements of a master device in a cluster receiving status information and selecting a network device based on that information in response to a DNS query. Arguments for dependent claims followed from this core teaching, covering aspects like the types of status information used and the application of predefined load-balancing algorithms.

Ground 2: Claims 1-17 are anticipated and/or obvious over Zisapel

  • Prior Art Relied Upon: Zisapel (Patent 6,665,702).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner asserted that Zisapel, which teaches load balancing across geographically distributed server farms, also discloses the claimed invention. Zisapel describes a primary load balancer (LB1) that functions as a master device for a cluster comprising servers and other load balancers. LB1 maintains a "server status table" by receiving status information (e.g., availability, load) from other devices in the cluster. Based on this information, LB1 receives a client request and directs it to an appropriate server, either in its local server farm or a remote one. Petitioner argued this system of a primary load balancer monitoring and directing traffic based on the status of clustered servers meets all limitations of the independent claims.

Ground 3: Claims 1-17 are obvious over Gourley in view of Zisapel

  • Prior Art Relied Upon: Gourley (“HTTP: The Definitive Guide”) and Zisapel (Patent 6,665,702).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground was presented as an alternative, asserting that if Gourley were found to provide the general architecture but lack specific details on implementing load-balancing algorithms, Zisapel supplies the missing elements. Gourley teaches the high-level concept of an authoritative DNS server using load information to select a web server. Zisapel explicitly discloses the conventional techniques for this process, such as a load balancer that "actively monitors each of the servers and returns a single address based on server load and availability."
    • Motivation to Combine: Petitioner argued a person of ordinary skill in the art (POSITA), seeking to implement the load-balancing system described conceptually in Gourley, would be motivated to consult a reference like Zisapel. Zisapel provided known, detailed methods for implementing the very functions Gourley’s system required, such as assessing server load and availability. The combination involved applying Zisapel's well-understood load-balancing techniques to Gourley's DNS server architecture, which was a simple and logical integration of known elements.
    • Expectation of Success: A POSITA would have a reasonable expectation of success in combining the references because it involved applying a known technique (Zisapel's load balancing) to a known system (Gourley's DNS architecture) to achieve a predictable result (efficient, load-based DNS resolution).

4. Arguments Regarding Discretionary Denial

  • Petitioner argued that the Board should not exercise discretionary denial under Fintiv because the co-pending district court litigation was in a relatively early stage, with fact discovery incomplete and trial scheduled months after a Final Written Decision (FWD) would issue.
  • To prevent overlap and duplication of effort, Petitioner stipulated that if the IPR was instituted, it would not pursue the same invalidity grounds based on Gourley or Zisapel in the district court action. Petitioner contended this stipulation, combined with the strong merits of the petition, weighs heavily in favor of institution and against denial.

5. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-17 of Patent 7,548,945 as unpatentable.