Prior art

The USPTO provides resources for searching patents and prior art. Prior art is information that was publicly known before the effective filing date of a U.S. patent application, which can include U.S. and foreign patents, published applications, journal articles, books, and websites.

US Patent 9900249, titled "Communication system, forwarding node, path management server, communication method, and program," was published on February 20, 2018, from an application filed on April 3, 2014. The priority date is September 14, 2009.

To identify the most relevant prior art and assess potential anticipation under 35 U.S.C. § 102, a detailed analysis of the patent's cited references and the claims themselves is necessary. However, without direct access to a comprehensive, searchable USPTO database that links specific citations to the claims they are asserted against in the examination history, I can provide a general overview based on the patent text's own discussion of prior art.

The patent itself identifies and discusses the following prior art:

Non-Patent Document 1: OpenFlow

• Full Citation: Nick McKeown, and 7 others, ‘OpenFlow: Enabling Innovation in Campus Networks’, [online], [search conducted Jul. 17, 2009] Internet URL: http://www.OpenFlowswitch.org//documents/OpenFlow-wp-latest.pdf
• Publication/Filing Date: Search conducted July 17, 2009. This predates the priority date of US9900249 (September 14, 2009).
• Brief Description: OpenFlow proposes a technology where communication is treated as end-to-end flow, and path control, recovery from failure, load balancing, and optimization are performed in flow units. An OpenFlow switch (functioning as a forwarding node) communicates with an OpenFlow controller via a secure channel and operates according to a flow table. This flow table defines rules for packet header collation, actions, and flow statistical information. If a packet is received and no conforming entry is found in the flow table, the OpenFlow switch forwards the packet to the OpenFlow controller to determine a path and update the flow table.
• Potential Anticipation (35 U.S.C. § 102): The patent discusses OpenFlow as related technology. The stated problem with OpenFlow is that "each forwarding node has to refer to a flow table, as in the method of referring to the routing table mentioned at the start of this specification, and it is considered that, accompanying an increase of entries, latency (delay time) occurs and loads are imposed on the nodes." This suggests that while OpenFlow involves a centralized controller and flow tables for path control, the claimed invention aims to overcome the overhead and processing load associated with large flow tables. Therefore, any claims of US9900249 that relate to "simplified forwarding table" or "reducing amount of memory" or "reducing packet forwarding delay" would be potentially anticipated or rendered obvious by OpenFlow if the differences are not sufficiently distinct. Specifically, claims related to the method of using identifiers in the packet header for forwarding at each hop to simplify forwarding table lookups distinguish it from OpenFlow's reliance on large flow tables.

Patent Document 1: Japanese Patent Kokai Publication No. JP-P2007-235444A

• Full Citation: Japanese Patent Kokai Publication No. JP-P2007-235444A
• Publication/Filing Date: The publication number indicates a publication date in 2007, which predates the priority date of US9900249 (September 14, 2009).
• Brief Description: This patent document relates to a method in an ad hoc network where the total amount of control packets can be reduced by having only a cluster head (a type of mobile terminal device) transmit link information between neighboring mobile terminal devices, rather than all devices.
• Potential Anticipation (35 U.S.C. § 102): The patent states that this method "cannot realize path control in which a source can specify a path as in the abovementioned source routing" due to the constantly changing network configurations of ad hoc networks. This implies that while it deals with network information exchange in a distributed manner, it does not address the centralized path control and explicit path specification for data packets that US9900249 aims to provide. Claims in US9900249 that involve a path management server configuring forwarding path information and the use of a header for explicit path forwarding would likely distinguish it from JP-P2007-235444A.

General Prior Art discussed in the patent's background:

• IP (Internet Protocol) Networks and Routing Tables:
  • Description: Traditional IP networks use forwarding nodes (switches/routers) with routing tables. These tables determine forwarding destinations based on network addresses and use a longest match method.
  • Problem Identified: Packet forwarding depends on routing tables of respective nodes, preventing complete path control. Forwarding is based only on destination address, limiting exact path control based on application or source address. Routing tables have grown large, leading to "routing information explosion," increased memory requirements, and declining packet forwarding processing capability due to longer route determination times.
  • Potential Anticipation (35 U.S.C. § 102): Any claims in US9900249 related to improving path control, enabling path specification based on more than just destination address (e.g., source address, application), reducing routing table size, and improving packet forwarding performance would need to demonstrate how they overcome the limitations of traditional IP routing. The core innovation of US9900249, using explicit, short identifiers in a header for hop-by-hop forwarding, directly addresses these issues.
• Source Routing (in IP networks):
  • Description: A source node explicitly lists addresses of desired forwarding nodes in a packet.
  • Problem Identified: Large overhead because full addresses of forwarding nodes are included, making it impractical for data packets.
  • Potential Anticipation (35 U.S.C. § 102): US9900249 aims to provide source routing-like control but with significantly reduced overhead by using "short information, 1 byte long, for example" for identifiers instead of full IP addresses. Claims specifying the compact nature of the identifiers and their arrangement in a header for path control would be key to distinguishing from prior art source routing.
• MPLS (Multi-Protocol Label Switching) and CR-LDP (Constraint Routing-Label Distribution Protocol):
  • Description: MPLS assigns labels to packets for forwarding. CR-LDP is an MPLS technology for strictly indicating a packet forwarding path, similar to source routing, by exchanging labels among forwarding nodes.
  • Problem Identified: While reducing route determination time compared to IP, applying varied forwarding policies increases the number of entries in the routing table, leading to declining processing capability. Like source routing, CR-LDP includes forwarding node information for each hop, often using IPv4 or IPv6 addresses, which increases the information amount and is not realistic for data packets outside of control packets. This necessitates setting forwarding information for each forwarding policy inside the forwarding node.
  • Potential Anticipation (35 U.S.C. § 102): Similar to source routing, claims in US9900249 that focus on the use of short, locally unique identifiers within the header of all packets (including data packets) to achieve precise path control without requiring extensive routing tables or increasing overhead significantly, differentiate it from CR-LDP. The ability to simplify forwarding tables and reduce memory by only storing correspondence between local IDs and interfaces, rather than large route entries for varied policies, is central to US9900249's claims over MPLS/CR-LDP.

In summary, the most relevant prior art as discussed within US9900249 itself revolves around methods of packet forwarding and path control (IP routing, source routing, MPLS/CR-LDP, OpenFlow) and their respective limitations regarding routing table size, overhead, and fine-grained path control. The patent aims to provide a system that offers explicit path control for data packets using simplified forwarding tables and minimal header overhead.