PTAB

IPR2026-00095

Microsoft Corp v. Sandpiper CDN LLC

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Key Events
Petition

1. Case Identification

2. Patent Overview

  • Title: Content Delivery System
  • Brief Description: The ’903 patent discloses a content delivery network (CDN) that enables origin servers to off-load the processing of resource requests. The system uses a network of shared "repeater servers" that replicate content from multiple origin servers and use a table correlating "alias names" to the names of origin servers to manage content delivery to client machines.

3. Grounds for Unpatentability

Ground 1: Claims 1, 2, 22-24, 26, 28-32, 35, 37, 38, 40, 41, and 43-45 are obvious over Kenner

  • Prior Art Relied Upon: Kenner (International Publication No. WO 1996/041285).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Kenner, which discloses a distributed video clip delivery system, taught every limitation of the challenged claims. Kenner's geographically dispersed "database index managers" (IMs) were asserted to be analogous to the "shared repeater servers" of the ’903 patent. These IMs replicate and store resources (video clips) from various "source IMs," which function as the claimed "origin servers." Petitioner contended that Kenner’s "clip database" is the claimed "table," as it stores information linking a "video ID" (the "alias name") for each clip to its corresponding source IM and content provider. This system is shown to support multiple content providers and deliver resources to multiple user terminals ("client machines"). The IMs use this database to locate and deliver requested content, thereby analyzing an alias name to determine the content's origin.
    • Key Aspects: Petitioner asserted that the core inventive concept of the ’903 patent—using a table with alias names on repeater servers to manage content from multiple providers—was fully disclosed in Kenner's scalable architecture for a distributed content delivery network.

Ground 2: Claim 33 is obvious over Kenner in view of Vetter

  • Prior Art Relied Upon: Kenner (WO 1996/041285) and Vetter (a 1994 publication titled "Mosaic and the World-Wide Web").
  • Core Argument for this Ground:
    • Prior Art Mapping: This ground addressed claim 33, which requires resources to be File Transfer Protocol (FTP)-based. Petitioner argued that while Kenner primarily discloses delivering HTTP-based content, Vetter explicitly teaches that web browsers like Mosaic use various protocols to access content, including FTP. Vetter shows that different protocols like HTTP and FTP are common, interchangeable schemes within a URL structure.
    • Motivation to Combine: A person of ordinary skill in the art (POSITA) would combine Kenner and Vetter to expand the types of resources available through Kenner's established content delivery network. Applying Vetter’s teaching of using FTP was presented as a simple, predictable modification to enhance the versatility of the Kenner system.
    • Expectation of Success: The combination would have been straightforward, as it involved applying a known data transfer protocol (FTP) to a known type of system (a CDN like Kenner's) to achieve a predictable result.

Ground 3: Claim 34 is obvious over Kenner in view of Rekimoto

  • Prior Art Relied Upon: Kenner (WO 1996/041285) and Rekimoto (European Patent Pub. No. EP 0753836).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground targeted claim 34, which requires the "alias name" to be a "domain name" and the network to include a "name server that provides domain name service (DNS) resolution." Petitioner argued Kenner’s system, while functionally similar, did not explicitly disclose DNS. Rekimoto was introduced for its teaching of a system that uses a mapping server with DNS resolution to identify the closest server to a user, thereby reducing network latency.
    • Motivation to Combine: A POSITA would have been motivated to incorporate Rekimoto's DNS capabilities into Kenner's geographically distributed network. The goal would be to improve system performance and reduce latency when selecting a server to fulfill a client request—a well-known advantage of using DNS for load balancing and proximity-based routing. Kenner already acknowledged the benefits of prioritizing servers by proximity.
    • Expectation of Success: Petitioner asserted a high expectation of success, as implementing DNS for server selection in a distributed network was a well-established and conventional technique at the time of the invention.

  • Additional Grounds: Petitioner asserted additional obviousness challenges against claims 27, 36, 39, 42, and 46 over Kenner in view of Boyles (Patent 5,511,208). The combination with Boyles was argued to teach rejecting a client request if the alias name is not found in the server's table, thereby providing an explicit failure notification to improve user experience.

4. Relief Requested

  • Petitioner requests institution of an inter partes review (IPR) and cancellation of claims 1, 2, 22-24, and 26-46 of the ’903 patent as unpatentable.