Selective PXE Subnet Filtering via IP Address

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Solution Overview

Problem

In complex PXE server environments, selecting the appropriate PXE server to respond to a PXE client is challenging due to the lack of identification of the client's MAC address before DHCP processing, leading to potential misassignment of boot environments.

Innovation Solution

Implementing a method where a PXE client broadcasts an initial DHCP request to obtain an IP address, then broadcasts a subsequent DHCP request with the IP address embedded, allowing PXE servers to filter and selectively respond based on the subnet, ensuring only the assigned server provides boot logic.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If PXE servers respond to all DHCP requests without filtering, then all clients can receive boot environments, but the wrong PXE server may service a client and deliver incorrect boot logic

Engineering Contradiction:

Improvecorrect boot environment deliveryVSAvoidPXE server filtering mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by having the PXE client obtain its IP address via DHCP before broadcasting the PXE request. This preliminary acquisition of network address information enables the PXE server to filter requests based on subnet matching, ensuring the correct server responds while avoiding the complexity of MAC address binding or post-DHCP server selection

Inventive Principle:

Principle #10Preliminary action

2Reliability

If PXE servers use MAC address binding to select the correct server, then selective PXE processing is achieved, but the system becomes tedious and error-prone

Engineering Contradiction:

Improveselective PXE processingVSAvoidMAC address management

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the filtering parameter from MAC address to IP address subnet. By comparing the subnet portion of the PXE client's IP address with the PXE server's assigned subnets, the system achieves selective PXE processing that is automatically maintained through DHCP lease management, eliminating the manual overhead of MAC address binding while preserving reliability

Inventive Principle:

Principle #35Parameter changes

3Reliability

If sub-net filtering is implemented before DHCP processing, then PXE servers can filter requests, but the PXE server cannot know the client's IP address

Engineering Contradiction:

Improvesubnet-based filteringVSAvoidIP address acquisition timing

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent resolves this timing issue by performing the DHCP IP address acquisition as a preliminary action before the PXE request broadcast. The client obtains its IP address first, then includes this information in the PXE request, allowing the server to perform subnet filtering without the loss of time associated with attempting pre-DHCP filtering

Inventive Principle:

Principle #10Preliminary action

4Ease of operation

If only the first responding PXE server is recognized after DHCP, then server selection is simple, but the client may receive boot logic from the wrong server

Engineering Contradiction:

ImprovePXE server selectionVSAvoidboot environment assignment

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent implements feedback by having the PXE server compare the client's IP address subnet against its assigned subnets before responding. This feedback mechanism ensures that only the appropriate PXE server responds to each client's broadcast, preventing the wrong server from providing boot logic while maintaining simple first-come-first-served operation

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9191460B2Selective sub-net filtering in a pre-boot execution environment (PXE)

Publication Date: 2015.11.17 LENOVO GLOBAL TECHNOLOGIES SWITZERLAND INTERNATIONAL GMBH

AI summary

Embodiments of the invention address deficiencies of the art in respect to PXE processing and provide a method, system and computer program product for selective PXE subnet filtering. In an embodiment of the invention, a PXE server subnet filtering method can be provided. The method can include selectively referring a PXE client to different boot logic depending upon at least a portion of a network assigned address for the PXE client. In this regard, selectively referring a PXE client to different boot logic depending upon at least a portion of a network assigned address for the PXE client can include selectively referring a PXE client to a different boot image notification layer (BINL) service providing a different filename for a different network bootstrap program depending upon at least a portion of an Internet protocol (IP) assigned address for the PXE client by a network resident dynamic host control protocol (DHCP) server in response to a previous DHCP request provided by the PXE client.