PTAB

IPR2026-00180

Microsoft Corp v. Sandpiper CDN LLC

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Content Delivery Network Caching Methods
  • Brief Description: The ’173 patent relates to a method for a node in a Content Delivery Network (CDN) to serve cached content. The patent’s purported novelty is a “late-binding” approach, where the current cache policy governing the content is determined at the time of a user request, rather than when the content was initially stored in the cache.

3. Grounds for Unpatentability

Ground 1: Obviousness over O’Rourke - Claims 1-2, 4-6, 8-9, and 11-13 are obvious over O’Rourke.

  • Prior Art Relied Upon: O’Rourke (Patent 7,912,921).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that O’Rourke teaches a cache server in a CDN that uses a flexible, user-determined set of cache policies to perform its functions. Petitioner mapped O'Rourke's disclosed process (Fig. 5), which shows checking if content is stored locally and then using policies to determine if the cached version is acceptable, directly to the limitations of independent claims 1 and 8. The ability in O’Rourke to add or remove "policy plug-ins" at any time was argued to teach the claimed concept of determining a "current cache policy" upon request, thus rendering the "late-binding" concept obvious.
    • Key Aspects: Petitioner contended that any minor differences in the sequence of steps between O'Rourke's process and the claims would have been an obvious design choice for a Person of Ordinary Skill in the Art (POSITA), as reordering the initial check for cached content and the identification of applicable policies would not change the system's fundamental operation or outcome.

Ground 2: Obviousness over O’Rourke and MS-MSSO - Claims 3 and 10 are obvious over O’Rourke in view of MS-MSSO.

  • Prior Art Relied Upon: O’Rourke (Patent 7,912,921) and MS-MSSO (Media Streaming Server System Overview, Microsoft Corporation, 2009).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed dependent claims 3 and 10, which add the limitations that the content request is an HTTP request and the content comprises one or more resources. Petitioner asserted that O'Rourke provides the foundational customizable cache server system and explicitly discloses that it can be implemented as a Windows Media Server. MS-MSSO, a technical document, describes the standard protocols for a Windows Media Server, specifying its use of the Windows Media HTTP Streaming Protocol for transferring multimedia data (i.e., resources).
    • Motivation to Combine: A POSITA implementing O'Rourke's system on a Windows Media Server, an embodiment suggested by O'Rourke itself, would naturally consult a document like MS-MSSO to understand its standard protocols. A POSITA would combine the two to leverage O'Rourke's flexible policy architecture with the known, predictable, and firewall-friendly benefits of the standard HTTP protocol taught by MS-MSSO for media streaming.
    • Expectation of Success: Petitioner argued the expectation of success would be high, as the combination involves implementing a disclosed embodiment (a Windows Media Server) using its known, standard operating protocols. This would yield the predictable result of a customizable cache server that communicates via HTTP.

Ground 3: Obviousness over Middleton and Blumofe - Claims 7 and 14 are obvious over Middleton in view of Blumofe.

  • Prior Art Relied Upon: Middleton (Application # 2011/0060812) and Blumofe (Application # 2012/0096106).
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground targeted claims 7 and 14, which require the cache policy to relate to caching content both within the CDN and outside the CDN. Middleton was cited for teaching an extensible CDN platform where an edge server uses cache policies, such as Time-To-Live (TTL) values, to manage content within the CDN. Blumofe was cited for teaching a "CDN Extender," a passive caching proxy designed to operate outside the CDN (e.g., in a wireless network) but under the control of the main CDN. Blumofe's Extender receives cache control instructions from the CDN to manage its externally cached content.
    • Motivation to Combine: A POSITA seeking to improve the performance of Middleton's CDN would be motivated to incorporate Blumofe's Extender. This combination would extend caching resources closer to end-users in environments like mobile networks where deploying a full CDN server is impractical. The motivation was to apply a single, consistent set of cache policies from a central CDN (per Middleton) to content cached both internally and externally (per Blumofe), thereby improving performance and maintaining policy coherence.
    • Expectation of Success: The expectation of success was argued to be high because Blumofe's Extender is explicitly designed to integrate with an existing CDN like that of Middleton. The combination applies a known technique (extending CDN reach with a proxy) to achieve the predictable result of improved network performance across more diverse network environments.
  • Additional Grounds: Petitioner asserted that claims 7 and 14 are also obvious over O'Rourke and Blumofe (Ground 1C). Petitioner further challenged claims 1-2, 4-6, 8-9, and 11-13 as obvious over Middleton alone (Ground 2A), and claims 3 and 10 as obvious over Middleton and MS-MSSO (Ground 2B), relying on similar arguments and motivations as presented in the grounds above.

4. Relief Requested

  • Petitioner requests institution of an inter partes review and cancellation of claims 1-14 of Patent 10,701,173 as unpatentable.