Signed SWI Extension Installation With Overlay Filesystem Boot
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Solution Overview
Problem
The installation of OS extensions on network devices requires manual handling by administrators, including downloading, installing, and configuring, which is tedious and error-prone, and results in significant memory usage impacting device functionality.
Innovation Solution
A dynamic installation method using a full SWI that contains a designated directory for ENOS extensions, allowing on-the-fly extraction and mounting of extensions in an overlay filesystem, minimizing RAM usage and eliminating separate download and installation steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If administrators manually download and install OS extensions separately, then extension functionality is added to the device, but the installation process becomes tedious and error-prone
Solution Approach 1:
The patent combines the OS extension package with the software image file (SWI) into a single integrated package. The extension package includes both the extension functionality and the necessary software image, allowing administrators to install everything in one operation rather than separately downloading extensions and configuring them manually.
Solution Approach 2:
The extension package is prepared in advance with all necessary components (extension code, software image, and installation metadata) bundled together. This preliminary packaging eliminates the need for administrators to perform separate download, extraction, and configuration steps during installation.
2Adaptability or versatility
If OS extensions are installed separately from the software image, then device functionality is extended, but memory usage increases significantly
Solution Approach 1:
The extension package is nested within the software image structure, with the extension code and resources embedded inside the SWI file format. This nested organization allows the system to load only the necessary extension components into memory rather than allocating separate memory spaces for extensions, thereby reducing overall memory usage while maintaining extended functionality.
3Adaptability or versatility
If administrators configure extension installation manually, then extension functionality is added, but the process becomes error-prone
Solution Approach 1:
The extension package includes embedded metadata and installation instructions that enable the system to automatically configure and install the extension without requiring manual administrator intervention. The package self-describes its installation requirements, dependencies, and configuration parameters, eliminating human error in the configuration process while maintaining full extension functionality.
Data Source
AI summary
For dynamic installation of extensible network operating system (ENOS) extensions, a network device downloads a full software image (SWI) having a signature and a directory containing software packages from an install source. During downloading, the network device modifies the full SWI on the fly, including reading and removing the software packages (SWIX files) from the directory, as each one is read, determining whether to keep it, for each “keep” SWIX file, extracting an ENOS extension and a corresponding signature, and storing them on a nonvolatile memory, resulting in a modified SWI with a signature but without the SWIX files. After download is complete, the signed ENOS extensions stored on the nonvolatile memory are verified to determine valid ENOS extensions for inclusion in an overlay filesystem which becomes a root filesystem for the network device. The signed modified SWI is also verified before booting the network device into the modified SWI.