Cloned Cable Modem Detector via DHCP Relay Analysis

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Cable operators face challenges in detecting service theft through cable modem cloning, as cloned modems can connect to different Cable Modem Termination Systems (CMTS) making detection difficult.

Innovation Solution

A cloned cable modem detector builds a table associating cable modem physical addresses with CMTS information and alerts operators when a physical address is associated with a different CMTS, using relayed provisioning requests to identify potential clones, even if the original and cloned modems are downstream from different CMTSs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If cloned modems connect to different CMTSs, then service theft becomes harder to detect, but detection accuracy deteriorates

Engineering Contradiction:

Improveservice theftVSAvoiddetection accuracy

Core Design Contradiction:

Object-affected harmful factorsVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces a DHCP relay agent as an intermediary component that intercepts provisioning requests between cable modems and DHCP servers. This relay agent collects MAC address and CMTS identifier information, enabling detection of cloned modems without requiring direct monitoring at the CMTS or DHCP server. The intermediary approach allows detection across multiple CMTSs while maintaining system architecture simplicity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary action by collecting and storing MAC address to CMTS identifier mappings in advance during the provisioning process. Before service theft can occur, the system establishes a baseline record of legitimate modem-CMTS associations, enabling subsequent detection of cloning attempts when a cloned modem tries to register with a different CMTS.

Inventive Principle:

Principle #10Preliminary action

2Difficulty of detecting and measuring

If the detector monitors all provisioning requests from all CMTSs, then detection capability improves, but device complexity increases

Engineering Contradiction:

Improvedetection capabilityVSAvoiddetector complexity

Core Design Contradiction:

Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

The DHCP relay agent performs multiple functions: it relays DHCP requests between cable modems and servers, collects detection data by examining request fields, and maintains association tables for detection purposes. By making the relay agent multi-functional, the patent avoids adding separate detection devices while still achieving comprehensive detection capability across all CMTSs.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the detection function with the existing DHCP relay function. Instead of creating a separate complex detection system, the detection capability is integrated into the relay agent that already processes provisioning requests, combining data collection, association tracking, and cloning detection into a single component.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS7986690B2Inter-gateway cloned device detector using provisioning request analysis

Publication Date: 2011.07.26 CISCO TECHNOLOGY INC

AI summary

In one embodiment, a cloned cable modem detector is configured to assemble a table associating cable modem physical addresses to Cable Modem Termination Systems (CMTSs) according to provisioning requests forwarded from the CMTSs. When one of the provisioning requests associates a cable modem physical address with a different CMTS than an existing association in the table, the detector outputs an indication of cable modem cloning.