Gateway Router PAT Entries for Private Network Device Discovery

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Solution Overview

Problem

Network Management Systems (NMS) cannot discover devices within private networks, as defined by RFC 1918, due to limitations in protocols like SNMP, which cannot traverse private network boundaries.

Innovation Solution

Implementing a method using a gateway router with Network Address Translation (NAT)/Port Address Translation (PAT) to establish static PAT entries, allowing NMS to access private network devices by rewriting IP addresses and ports, and utilizing telnet/ssh to communicate directly with devices behind the private network.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If SNMP and discovery protocols are used to discover network topology, then the NMS can discover devices on public networks, but the NMS cannot discover devices on private networks

Engineering Contradiction:

Improvenetwork discovery capabilityVSAvoidprivate network boundary limitation

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The gateway router acts as an intermediary between the public network and private network. It receives SNMP requests from the NMS, translates them into direct connections with private network devices, and facilitates communication. This mediator enables the NMS to discover private network devices without directly accessing them, resolving the boundary limitation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The discovery process is segmented into phases: first discovering the gateway router on the public network, then establishing separate direct connections to each private network device through the gateway. This segmentation allows the NMS to overcome the private network boundary by handling discovery in discrete, manageable steps.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If the NMS establishes direct connections to private network devices through the gateway, then device discovery is enabled, but security risks increase

Engineering Contradiction:

Improveaccess to private network devicesVSAvoidsecurity risks

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The system performs preliminary actions by first discovering the gateway router and establishing a secure connection to it before accessing private network devices. The NMS obtains the gateway's IP address and establishes a direct connection to the gateway first, creating a secure foundation before proceeding to discover and connect to private devices through the gateway's facilitated connections.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The gateway router serves as a security intermediary that controls access to private network devices. It translates SNMP requests, manages connections, and acts as a buffer between the NMS and private devices. This intermediary approach enables device access while maintaining security through the gateway's controlled translation and routing functions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7903585B2Topology discovery of a private network

Publication Date: 2011.03.08 CISCO TECHNOLOGY INC

AI summary

The present invention relates to a method and system for determining devices connected to a private network through a gateway. A Network Management System (NMS) through the use of inquiries and Port Address Translation (PAT) commands is able to determine the topology of the network of devices within a private network and thus communicate with them. This is achieved through the use of Port Address Translation (PAT) initiated by the NMS to set a port for each device connected to the gateway.