Blade Server Slot ID Inference via Secure Ethernet Broadcast

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Solution Overview

Problem

Blade servers in server chassis lack dedicated connector pins for communicating physical slot IDs, necessitating a need for alternative methods to determine slot IDs without relying on dedicated pins.

Innovation Solution

A communication protocol between a blade server and a server chassis is established using a BMC and CMC to infer the physical slot ID through the exchange of Ethernet frames over a broadcast domain, utilizing a Type-Length-Value (TLV) sequence to encode and decode information, and employing cryptographic certificates for verification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dedicated connector pins are used to communicate physical slot ID to blade servers, then slot ID communication is reliable, but connector pin resources are consumed and cannot be used for other functions

Engineering Contradiction:

Improveslot ID communication reliabilityVSAvoidconnector pin availability for other functions

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies universality by enabling existing connector pins to serve multiple functions. Specifically, pins originally designated for other purposes (such as power distribution or data exchange) are repurposed to communicate physical slot IDs through protocol-based inference mechanisms, allowing the same hardware resources to fulfill both their original function and the new slot ID communication function simultaneously

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces an intermediary approach by using protocol layers and management controllers (such as BMC/CMC) to mediate between the physical connector pins and the blade server. Instead of directly encoding slot IDs on dedicated pins, the system uses intermediary software protocols to infer and communicate slot ID information through existing pin assignments, thereby avoiding direct hardware dedication while maintaining communication reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If connector pins are dedicated to power distribution and data exchange, then those functions are optimized, but slot ID communication becomes unavailable

Engineering Contradiction:

Improvecomputing performanceVSAvoidphysical slot ID information

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The patent replaces the mechanical/hardware-based slot ID communication method (dedicated connector pins) with a software/protocol-based approach. Instead of relying on physical pin assignments, the system uses Ethernet frame exchanges and protocol-level interactions between management controllers to convey slot ID information, substituting a hardware solution with a software-based information exchange mechanism

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the parameter of communication from physical pin assignment to protocol-based data exchange. By transforming the communication mechanism from a hardware-level electrical signal on dedicated pins to a software-level protocol message over existing data channels, the system maintains information transmission while preserving connector pin availability for high-priority functions

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If protocol-based slot ID inference is implemented, then connector pin resources are preserved, but communication complexity increases

Engineering Contradiction:

Improveconnector pin utilizationVSAvoidcommunication protocol complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies self-service by enabling the system to automatically infer and determine physical slot IDs through protocol exchanges without requiring manual configuration or additional hardware resources. The management controllers autonomously perform the inference process by analyzing existing communication channels and pin assignments, thereby reducing the need for human intervention while managing the protocol complexity internally

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS12531938B2Communication protocol for inference of physical slot identifier by baseboard management controller of blade server

Publication Date: 2026.01.20 CISCO TECHNOLOGY INC

AI summary

This disclosure describes techniques for interoperability of a blade server in a server chassis, where IOMs of the server chassis do not provide dedicated pins for communicating a physical slot ID to the blade server. BMCs of the blade servers and CMCs of IOMs of the server chassis are mutually configured to broadcast Ethernet frames on layer 2 network segments over a broadcast domain configured by a switch module connected to the blade servers over layer 2 network segments; conduct a slot inference communication protocol using these Ethernet frame broadcasts to enable the CMC to determine a physical slot ID in response to a BMC request, and broadcast that physical slot ID back to the BMC; and use a public certificate-private certificate pair, based in a hardware root of trust, to enforce security of this communication protocol.