Cisco Systems Inc v. Portsmouth Network Corp

1. Case Identification

• Case #: IPR2024-00506
• Patent #: 8,014,394
• Filed: March 31, 2024
• Petitioner(s): Cisco Systems, Inc.
• Patent Owner(s): Portsmouth Network Corp.
• Challenged Claims: 1-2, 4-12, and 14-18

2. Patent Overview

• Title: Communication Method and Network Element
• Brief Description: The ’394 patent describes methods and systems for managing multicast packet streams in a network element having a distributed architecture. The system uses multiple interconnected processing units to control multicast forwarding, including applying bandwidth limits to high-capacity ports formed by aggregating multiple physical ports.

3. Grounds for Unpatentability

Ground 1: Claims 1, 4, 6-7, 11, 14, and 17 are obvious over Weyman and Li

• Prior Art Relied Upon: Weyman (Application # 2005/0041665) and Li (WO 2007/140702).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Weyman disclosed the core architecture of the ’394 patent: a distributed router ("network element") with multiple interconnected processing units, each having its own forwarding table ("list"). Weyman also taught aggregating multiple physical ports to form a high-capacity aggregated link. Petitioner contended that Li taught the missing element: a port bandwidth control technique for an IGMP-based multicast router. Li’s method involved setting a maximum number of allowable multicast streams for a given port and rejecting new requests if that limit would be exceeded.
  • Motivation to Combine: A POSITA would combine Weyman's distributed router with Li's bandwidth control method to solve the known problem of overloading ports and degrading network reliability. Weyman itself recognized the need for workload sharing, and Li provided an explicit, known technique for controlling bandwidth by limiting stream counts. This combination was presented as a predictable solution to a known problem.
  • Expectation of Success: A POSITA would have a reasonable expectation of success because both references operated in the same technical field of IGMP-based multicast routing. Implementing Li's straightforward channel-counting logic within each of Weyman's processing units was argued to be a predictable implementation yielding the expected result of preventing port overload.

Ground 2: Claims 8 and 18 are obvious over Weyman in view of Jain and LeMaire

• Prior Art Relied Upon: Weyman (Application # 2005/0041665), Jain (Application # 2006/0224877), and LeMaire (Patent 5,999,530).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground addressed claims related to initializing a new processing unit added to the network. Petitioner asserted that while Weyman taught that a new unit could be added, it did not detail the initialization process. Jain taught a "controlled boot-up process" where a new network node first deactivates its ports ("Link Down") to prevent traffic disruptions while it undergoes internal configuration. LeMaire taught an initialization technique for a multicast bridge where, upon power-up, it sends IGMP queries to clients to learn multicast memberships and populate its forwarding tables.
  • Motivation to Combine: A POSITA would be motivated to combine these teachings to implement a complete and robust initialization sequence for a new unit in Weyman's router. Since Weyman lacked specifics, a POSITA would look to known techniques. Jain provided the method for safely bringing a unit online without causing network errors by deactivating ports first. LeMaire provided the established IGMP-based method for building the necessary forwarding tables from scratch.
  • Expectation of Success: Success was expected because the combination involved applying well-understood, standard network initialization procedures to a known distributed router architecture. The steps were sequential and non-contradictory: deactivate ports (Jain), query for membership and build tables (LeMaire), and then reactivate ports (Jain).

Ground 3: Claims 5 and 15 are obvious over Weyman and Li in view of Rooholamini

• Prior Art Relied Upon: Weyman (Application # 2005/0041665), Li (WO 2007/140702), and Rooholamini (Application # 2007/0297406).

• Core Argument for this Ground:

  • Prior Art Mapping: This ground built upon the Weyman/Li combination to address claims requiring each processing unit to hold "local copies of the number of the multicast packet streams" permitted on a high-capacity port. Petitioner argued that Rooholamini disclosed this exact feature, teaching a distributed router that maintains a "port path count table" in each switch. This table tracked, in real-time, the number of multicast streams passing through each specific port of each switch.
  • Motivation to Combine: A POSITA implementing the Weyman/Li combination would need an efficient way to track the number of active streams per port to enforce Li's bandwidth limit. Rooholamini provided a known and direct solution for this. A POSITA would be motivated to place this port count table locally within each processing unit, as taught by Rooholamini, to reduce latency and minimize traffic on the internal fabric link, a design goal explicitly mentioned in Weyman.
  • Expectation of Success: The combination was presented as highly predictable, as it involved integrating a known data tracking structure (Rooholamini's count table) to enable a known function (Li's bandwidth control) within a known architecture (Weyman's distributed router).

• Additional Grounds: Petitioner asserted other obviousness challenges, including combinations with Pitcher (Patent 6,370,142) to teach aging out and removing stale forwarding table entries using a timer, and with Ding (Application # 2006/0146823) to teach implementing forwarding logic in dedicated hardware.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial is not warranted. Under Fintiv, Petitioner provided a Sotera stipulation agreeing not to pursue in district court any grounds that were raised or reasonably could have been raised in the IPR. The parallel litigation was described as being in its early stages, with no claim construction briefing started. Petitioner also argued denial under §325(d) is inappropriate because the prior art references cited in the petition were not considered during prosecution and are not cumulative to the art of record.

5. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1-2, 4-12, and 14-18 of the ’394 patent as unpatentable.