F5 Networks Inc v. Proven Networks LLC

1. Case Identification

• Case #: IPR2021-01164
• Patent #: 7,450,507
• Filed: June 21, 2021
• Petitioner(s): F5 Networks, Inc.
• Patent Owner(s): Proven Networks, LLC
• Challenged Claims: 1-9 and 13-19

2. Patent Overview

• Title: Hierarchal Rate-Limiting at a Network Node That Utilizes an Infinity Rate-Limit Check
• Brief Description: The ’507 patent describes systems and methods for hierarchical rate-limiting of network traffic. The purported invention is the use of an "infinity rate-limit check," which grants an automatic pass to a data packet at a lower (child) level of a traffic classification hierarchy, allowing the packet to borrow bandwidth from a higher (parent) level if available.

3. Grounds for Unpatentability

Ground I: Anticipation of Claims 1, 2, and 6-9 by Hussain

• Prior Art Relied Upon: Hussain (Patent 7,161,904).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Hussain discloses every element of the challenged claims. Hussain teaches a hierarchical rate-limiting system where packets are subjected to checks at multiple levels (child and parent). Crucially, Hussain describes a configurable "no dropping" policy for its metering control blocks (MCBs). Petitioner asserted this policy is the same as the ’507 patent’s "infinity rate-limit check," as it instructs the system not to drop a packet that fails a child-level rate check, thereby extending its life and passing it to the next, higher level of metering. This grants an automatic pass at the child level, with the overall pass/fail decision depending on the parent-level check, directly mapping to the limitations of claim 1.
  • Key Aspects: Petitioner contended that Hussain’s "no dropping" policy, when applied to a child-level flow, allows packets to exceed their specified limits if a higher-level profile has not been exceeded, which is functionally identical to the bandwidth borrowing enabled by the claimed "infinity rate-limit check."

Ground II: Obviousness of Claims 1-9 and 13-19 over Kiremidjian in view of Hussain

• Prior Art Relied Upon: Kiremidjian (Application # 2003/0081623) and Hussain (Patent 7,161,904).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted Kiremidjian discloses a hardware-based, parallel-architecture hierarchical rate-limiter that classifies packets and subjects them to multiple levels of rate checks based on service-level policies. While Kiremidjian describes using flags to configure policies, it does not explicitly disclose a rule that grants an automatic pass regardless of a rate-check failure. Hussain supplies this missing element with its "no dropping" policy.
  • Motivation to Combine: A POSITA would have been motivated to combine the teachings to improve Kiremidjian's system. Kiremidjian already used "scan flags" and "virtual queue flags" for flexible configuration. A POSITA would combine this with Hussain’s "no dropping" policy to implement the well-known technique of bandwidth borrowing, which would have been an attractive and obvious configuration option to add. This would improve the configurability and functionality of Kiremidjian’s traffic shaping system.
  • Expectation of Success: A POSITA would have a reasonable expectation of success because Kiremidjian already used node-specific policy flags to control packet queueing and forwarding. Implementing Hussain's policy would simply involve defining a "no queuing" flag to prevent a packet from being queued upon a rate-limit failure, which is a straightforward modification of Kiremidjian’s existing architecture.

Ground III: Obviousness of Claims 1-3, 6-9, 13-17, and 19 over Gingras

• Prior Art Relied Upon: Gingras (Patent 7,664,028).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued Gingras teaches a two-level hierarchical metering system using "primary" (child-level) and "secondary" (parent-level) meters. For each metering outcome at the primary meter (e.g., non-conformant), Gingras teaches that one of three actions can be configured: DISCARD, REMARK, or "NO ACTION." Petitioner contended that the "NO ACTION" option is the equivalent of the ’507 patent’s "infinity rate-limit check." Selecting "NO ACTION" for a non-conforming packet causes the system to ignore the primary meter's failure and forwards the packet to the secondary meter for a final decision, effectively granting an automatic pass at the child level.
  • Motivation to Combine: A POSITA would have been motivated to configure Gingras to associate the "NO ACTION" option with a non-conformant outcome. This would be a simple and straightforward way to implement the well-known and desirable technique of bandwidth borrowing within the disclosed framework of Gingras.
  • Expectation of Success: Success would be expected because Gingras explicitly discloses that any of the three actions, including "NO ACTION," can be associated with any of the metering outcomes. No modification is needed, only a routine configuration choice.

4. Key Claim Construction Positions

• "infinity rate-limit check": Petitioner argued this term was coined by the applicants and lacks a plain and ordinary meaning in the art. Based on the patent’s specification and prosecution history, Petitioner asserted the term must be construed as "a rule that grants an automatic pass to a packet at a child classification level regardless of the outcome of the rate-limit check at that child classification level." This construction is central to all grounds, as Petitioner maps the prior art’s "no dropping" and "NO ACTION" policies directly to this definition.

5. Arguments Regarding Discretionary Denial

• Petitioner argued discretionary denial under §314(a) is inappropriate. The petition was filed with a timely Motion for Joinder with a previously instituted IPR against the same patent (IPR2021-00196, filed by VMware).
• Petitioner noted that the Board already found the grounds asserted in the VMware petition, which are identical to the grounds in this petition, demonstrated a reasonable likelihood of success and declined to exercise discretionary denial in that proceeding.

6. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-9 and 13-19 as unpatentable under 35 U.S.C. §102 and §103.