Cisco Systems Inc v. Corrigent Corp

1. Case Identification

• Case #: IPR2023-00168
• Patent #: 7,113,485
• Filed: November 17, 2022
• Petitioner(s): Cisco Systems, Inc., Dell Technologies Inc., and Dell Inc.
• Patent Owner(s): Corrigent Corporation
• Challenged Claims: 1-20

2. Patent Overview

• Title: Method for Measuring Latency in a Packet-Switched Network
• Brief Description: The ’485 patent discloses methods for measuring latency in packet-switched computer networks, including networks with a ring topology. The invention covers methodologies for measuring latencies for different classes of service, calculating round-trip latency between pairs of nodes, and monitoring latency variations over time.

3. Grounds for Unpatentability

Ground 1: Obviousness over Klassen - Claims 6-7 and 16-17 are obvious over Klassen

• Prior Art Relied Upon: Klassen (Patent 6,711,137).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Klassen taught every limitation of independent claims 6 and 16. Klassen disclosed a "method for network measurement" that uses "probative test packets" to derive latency, applicable in "all topologies." It further taught that these test packets include "type of service" or "class of service" bits in their headers, which are used to perform network measurements at "different priority levels." This directly maps to the claimed method of measuring latency for traffic transmitted in a plurality of classes of service. Petitioner asserted it would have been an obvious design choice for the same entity that sends and receives the test packets (Klassen's ANSA) to also generate them for efficiency.
  • Motivation to Combine: Not applicable (single reference ground).
  • Expectation of Success: Not applicable.

Ground 2: Obviousness over Klassen and Geiger - Claims 9 and 19 are obvious over Klassen in view of Geiger

• Prior Art Relied Upon: Klassen (Patent 6,711,137) and Geiger (Patent 5,701,302).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that Klassen taught sending a sequence of "probative test packets" at fixed intervals to measure latency and monitor variations such as jitter. However, Klassen provided limited detail on how a receiving node should handle these packets, particularly if they arrive out of order. Geiger addressed this by teaching a method where a receiving device can ignore packets received out of sequence, as indicated by their serial numbers. The combination of Klassen's latency monitoring with Geiger's specific protocol for handling out-of-order packets allegedly rendered the limitations of claim 9 obvious.
  • Motivation to Combine: A POSITA would combine Geiger’s known technique for handling out-of-order packets to improve Klassen’s general latency measurement process. Because network packets can be received out of order, a POSITA implementing Klassen's method would have been motivated to incorporate a standard handling protocol like Geiger's to ensure predictable and accurate network measurements.
  • Expectation of Success: Petitioner argued a POSITA would have had a reasonable expectation of success because both references relate to network packet transmission. Applying Geiger's specific packet-handling rules to Klassen's general measurement framework was presented as a straightforward integration of a known technique into a similar system.

Ground 3: Obviousness over Klassen, Kao, and Poulin - Claims 1-4, 8, 11-14, and 18 are obvious over Klassen, Kao, and Poulin

• Prior Art Relied Upon: Klassen (Patent 6,711,137), Kao (Patent 7,212,490), and Poulin (Patent 6,545,979).

• Core Argument for this Ground:

  • Prior Art Mapping: Petitioner argued this combination taught the limitations of independent claim 1. Klassen provided the foundational method for measuring latency using test packets in any topology. Kao supplied the specific context of a dual-ring network where traffic flows in mutually opposite directions. Poulin provided a detailed method for calculating round-trip latency that isolates and removes node processing delays. Poulin achieved this by using four distinct timestamps (send/receive at originating node, receive/send at peer node) and calculating a "delta value" representing the processing time at the peer node, which is then subtracted from the total round-trip time.
  • Motivation to Combine: A POSITA would have been motivated to apply Klassen's universal latency measurement method to the specific, well-known dual-ring topology described by Kao, viewing it as a simple substitution of one known element (a generic topology) for another (a specific ring topology). Poulin would then be combined to improve the accuracy of Klassen's method by providing a more granular calculation that accounts for device-specific delays, a known technique for refining latency measurements.
  • Expectation of Success: Success was expected because the references described complementary techniques. Implementing Klassen's general measurement system in Kao's specific network topology and enhancing it with Poulin's more precise calculation method was a logical combination of known elements to achieve a predictable result.

• Additional Grounds: Petitioner asserted additional obviousness challenges for the remaining claims based on combinations of Klassen, Kao, Geiger, and Poulin, which built upon the core arguments presented in the grounds above.

4. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under 35 U.S.C. §325(d) was inappropriate because none of the asserted prior art references or combinations were presented to or considered by the Examiner during the original prosecution of the ’485 patent.
• Petitioner further contended that discretionary denial under Fintiv factors was not warranted. The arguments centered on the early stages of the parallel district court litigations, the distant and uncertain trial dates (over two years on average), minimal investment in those proceedings, and a commitment by Petitioners to not pursue the same invalidity grounds in district court if the IPR is instituted.

5. Relief Requested

• Petitioner requests the institution of an inter partes review and the cancellation of claims 1-20 of Patent 7,113,485 as unpatentable.