PTAB

IPR2021-01594

Splunk Inc v. Sable Networks Inc

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Implementing a Plurality of Logical Routers Within a Single Physical Router
  • Brief Description: The ’358 patent is directed to a system for implementing multiple logical routers within a single physical router. The system establishes internal, non-physical links between these logical routers and advertises this internal topology so the logical routers appear to external routers as interconnected, standalone devices.

3. Grounds for Unpatentability

Ground 1: Obviousness over Hardwick - Claims 1-15, 23-28, 32, 43-51, and 97 are obvious over Hardwick.

  • Prior Art Relied Upon: Hardwick (Patent 5,550,816).
  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that Hardwick, a reference not considered during prosecution, teaches all limitations of the challenged claims. Independent claim 1 recites a physical router implementing first and second logical routers, a forwarding routing table with an identifier indicating a link is internal, and functionality to establish and advertise this internal link. Petitioner contended that Hardwick’s disclosure of implementing multiple "virtual routers" (VRs) using object-oriented software on a single physical "router platform" teaches the claimed "logical routers." Hardwick's teaching of partitioning physical interfaces among these VRs was argued to meet the limitations for first and second sets of components implementing the logical routers.

    • Petitioner asserted that Hardwick’s "Virtual Link," described as a logical, non-physical medium used to "internally connect[] these VRs," directly teaches the claimed internal link between logical routers. The key limitation of a "forwarding routing table that comprises an identifier that indicates an internal link is internal rather than an external link" was allegedly taught by a combination of features in Hardwick. This included a "VirtualLinkData table" that identifies the remote protocol port and VR associated with an internal connection, routing tables, and a database of known destination identifiers. Petitioner argued these features collectively provide a mechanism for distinguishing internal inter-VR connections from external network connections for packet forwarding. Finally, Hardwick’s teaching of running known routing protocols like OSPF within each VR for "automatic route discovery" was argued to meet the limitation of advertising the internal link such that the logical routers appear as interconnected standalone routers to the external network.

    • Expectation of Success: Petitioner contended that a person of ordinary skill in the art (POSITA) would have had a high expectation of success in implementing Hardwick's system. The reference described using well-understood networking concepts, including virtual routing on a shared platform, forwarding tables, and standard routing protocols that were common in the art at the time.

    • Key Aspects: Petitioner emphasized that Hardwick directly addresses the features the patent owner relied upon during prosecution to overcome prior art rejections, specifically the use of logical, non-physical internal links.

4. Key Claim Construction Positions

  • Petitioner provided constructions for several means-plus-function limitations found in dependent claims 26-28 and 32, which it argued were critical to the invalidity analysis.
  • For "means for implementing one or more routing protocols to advertise said internal link" (claims 26, 27), Petitioner identified the corresponding structure in the ’358 Patent as the Protocol manager 702, APM 308, and line cards 302.
  • For "means for maintaining a first internal interface associated with said first logical router" (claim 28), Petitioner identified the structure as APM 308, Provisioning module 604, and internal interfaces 208.
  • For "means for constructing a...forwarding table" (claim 32), Petitioner identified the corresponding structure as APM 308, Protocol manager 702, provisioning module 604, and forwarding tables 706.

5. Key Technical Contentions (Beyond Claim Construction)

  • Petitioner's primary technical contention was that a POSITA would have understood the "virtual routers" disclosed in Hardwick to be functionally and structurally equivalent to the "logical routers" claimed in the ’358 Patent.
  • Petitioner argued that both terms describe software-based emulations of physical routers that run on shared hardware resources, a concept that was well-established in the field of computer networking prior to the patent's priority date.

6. Arguments Regarding Discretionary Denial

  • Petitioner argued that discretionary denial under Fintiv would be inappropriate and inequitable, presenting arguments across several factors favoring institution of the inter partes review (IPR).
  • Petitioner contended that the parallel district court litigation was in its early stages, with a motion to stay filed and minimal investment by the court or parties in discovery or claim construction, which weighed heavily in favor of institution (Factors 1 & 3).
  • The scheduled trial date was over a year away and subject to uncertainty, further favoring institution (Factor 2).
  • Petitioner also committed to a stipulation not to pursue in district court the same invalidity grounds raised in the petition, mitigating concerns of duplicative efforts and inconsistent rulings (Factor 4).
  • Finally, Petitioner asserted that the strong merits of the petition, based on a primary prior art reference never considered by the examiner, provided a compelling independent reason for the Board to institute review (Factor 6).

7. Relief Requested

  • Petitioner requests institution of an IPR and cancellation of claims 1-15, 23-28, 32, 43-51, and 97 of Patent 7,630,358 as unpatentable.