L2VPN Connectivity Detection via ICMP Round-Trip Time

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Solution Overview

Problem

Current methods for detecting connectivity in Layer 2 Virtual Private Networks (L2VPNs) are limited, as they either require support for CFM across all base stations or knowledge of MAC addresses, which is not always available, making accurate and rapid fault detection challenging.

Innovation Solution

A method using ICMP PING to detect connectivity between a source and destination address in an L2VPN by transmitting an ICMP request packet and calculating the round-trip time, which is applicable to all base stations supporting IP PING, offering wider scenarios, simple operations, and improved detection efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If CFM solution is used to detect connectivity between base station and UNI of PTN device, then connectivity detection capability is improved, but it is impossible to ensure all base stations support the CFM

Engineering Contradiction:
Improveconnectivity detection capabilityVSAvoidcompatibility with base stations
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent introduces an intermediary device (network management system or gateway) that translates between CFM protocols and ICMP PING protocols. This intermediary enables connectivity detection for base stations that do not natively support CFM by converting their responses into a format that can be interpreted by the detection system, thus resolving the compatibility issue while maintaining detection reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a virtual copy of the CFM detection mechanism using ICMP PING protocols. Instead of requiring all base stations to implement the complex CFM protocol stack, the system uses simplified ICMP PING messages that replicate the essential connectivity detection functionality, making it universally compatible while preserving the core detection capability.

Inventive Principle:
Principle #26Copying

2Ease of operation

If MAC-PING solution is used for connectivity detection, then operation simplicity is improved, but connectivity detection of some nodes is unavailable unless MAC address information is known

Engineering Contradiction:
Improveoperation simplicityVSAvoiddetectability of unknown nodes
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent performs preliminary MAC address discovery through ARP (Address Resolution Protocol) queries before executing the PING operation. The system first resolves the MAC address of the target node using its IP address, ensuring that when the PING operation commences, the necessary MAC address information is already available, thus enabling detection of nodes whose MAC addresses were initially unknown.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where the system monitors PING response results and automatically adjusts its detection strategy. When MAC addresses are unknown or PING operations fail, the system receives feedback about the failure condition and initiates alternative discovery methods, such as scanning or querying network management databases, to obtain the necessary address information for subsequent detection attempts.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3151467B1Method and apparatus for detecting user network interface connectivity of virtual private network
Publication Date: 2020.08.26 ZTE CORP
  • EP3151467B1 patent drawingFigure 1
  • EP3151467B1 patent drawingFigure 2
  • EP3151467B1 patent drawingFigure 3~4

AI summary

The present invention provides a method and apparatus for detecting a user network interface connectivity of a virtual private network. The method comprises: acquiring configuration parameters used for detecting a user network interface connectivity between a source address and a destination address in the virtual private network; sending an Internet Control Message Protocol (ICMP) request packet from the source address to the destination address through the configuration parameters, and receiving an ICMP response packet returned by the destination address; and after receiving the ICMP response packet returned by the destination address, calculating a round-trip delay value of a link between the source address and the destination address according to the calculated round-trip delay value. Therefore, the user network interface connectivity of the virtual private network can be detected accurately and rapidly.