PTAB

IPR2018-00161

F5 Networks Inc v. Radware Ltd

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: System for Managing a Multi-Homed Network
  • Brief Description: The ’853 patent relates to techniques for managing a “multi-homed” network, in which a client computer network is connected to the Internet through multiple Internet Service Providers (ISPs). The invention uses a content router to select an optimal data route for client requests and performs network address translation (NAT) to ensure requests and their corresponding responses are transmitted along the selected route.

3. Grounds for Unpatentability

Ground 1: Claims 3 and 16 are obvious over Veerina in view of Ota.

  • Prior Art Relied Upon: Veerina (Patent 6,243,379) and Ota (Patent 5,347,272).
  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that the combination of Veerina and Ota teaches every limitation of challenged dependent claims 3 and 16. Petitioner asserted that Patent Owner had already conceded in a related proceeding (IPR2017-00124) that Veerina anticipates or renders obvious the base claims (1, 2, 14, and 15) upon which the challenged claims depend. Veerina was said to disclose a multi-homed network router that receives client requests, selects from a plurality of data routes based on a decision function (e.g., a "link-selection algorithm"), routes the request, and performs NAT on both outgoing requests and incoming responses.

      The sole limitation that the Board previously found untaught by Veerina was the requirement of claims 3 and 16 for "routing subsequent requests... wherein the routing is performed during a predefined period of time." Petitioner contended that Ota remedies this. Ota discloses a network system that determines and stores the shortest communication route, but crucially, it also teaches deleting that stored route information after a "predetermined time has elapsed." Ota describes tracking the "age" of routing information and deleting it if it exceeds a "Routing Information Expiration Time," or deleting it if it has been unused for a "predetermined period of time." By deleting the route information, Ota ensures that routing over that specific path can only occur during the defined period before expiration, directly teaching the disputed limitation as construed by the Board.

    • Motivation to Combine: Petitioner asserted that a person of ordinary skill in the art (POSITA) would have been motivated to combine the teachings of Veerina and Ota. Both references are in the same technological field of distributed network communications and address the identical problem of selecting and managing routes across a network. Ota explicitly states that expiring out-of-date route information is desirable because "there is the possibility that the state of the network has changed." A POSITA would have recognized the clear benefit of incorporating Ota's time-based route expiration into Veerina's multi-homed routing system. This would improve the robustness of Veerina's load-balancing by forcing a periodic re-evaluation of routes, preventing traffic from being sent over a WAN link that may have degraded or failed.

    • Expectation of Success: Petitioner argued that a POSITA would have had a high expectation of success in making this combination. The integration was presented as the "predictable use of prior art elements according to their established functions." Applying a known, simple technique (time-based expiration) from Ota to the known system of Veerina to achieve the predictable and desirable result of improved network resilience was characterized as a trivial modification.

    • Key Aspects: This petition is a "follow-on" petition filed specifically to address the Board's claim construction of "predefined period of time" from the prior IPR. The denial of institution for these claims in the first proceeding prompted Petitioner to identify the Ota reference to specifically address the Board's narrow construction.

4. Key Claim Construction Positions

  • "predefined period of time": This term was central to the petition. Petitioner noted that in the decision for the prior IPR, the Board construed this phrase in claims 3 and 16 to require that the routing "relates to an expiration of such established routing." The Board held that this required a discrete expiration point, and that Veerina’s teaching of routing for as long as a connection persists was insufficient. While not agreeing with this interpretation, Petitioner explicitly adopted the Board's construction for the purposes of this follow-on petition, arguing that the combination with Ota's route expiration teachings renders the claims obvious even under this narrower standard.

5. Arguments Regarding Discretionary Denial

  • Petitioner dedicated a significant portion of its argument to explaining why the Board should exercise its discretion to institute this follow-on petition and not deny it under the factors outlined in General Plastic. Petitioner contended this filing was not an abusive litigation tactic but was directly necessitated by the Board's adverse claim construction in the first IPR, which it had not anticipated.
  • Petitioner argued that it was not previously aware of the Ota reference or its specific applicability, and that the search for such art was prompted only by the Board's narrow construction. It was asserted that Patent Owner's own infringement contentions in district court litigation did not suggest such a narrow interpretation, leaving Petitioner without notice.
  • To conserve the Board's resources, Petitioner narrowly tailored this petition to challenge only the two dependent claims with identical limitations, based on a single ground and a single new reference, allowing the Board to focus solely on the discrete issue of the "predefined period of time" limitation.

6. Relief Requested

  • Petitioner requested that the Board institute an inter partes review and cancel claims 3 and 16 of Patent 9,231,853 as unpatentable under 35 U.S.C. §103.