Bandwidth Probing Messages for NAT Traversal

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Solution Overview

Problem

Networks with unknown bandwidth and latency metrics experience disruptions in communications due to the presence of NAT devices, which block or misroute inbound communications from outside devices to endpoint devices behind NATs, causing issues like VoIP disruptions.

Innovation Solution

A method involving endpoint devices sending probing packets to a relay server to determine network characteristics such as bandwidth, jitter, and delays by requesting an address and port assignment, sending probing packets, and analyzing response packets to assess network conditions, using protocols like TURN and STUN for NAT traversal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If NAT devices are deployed to translate address information, then address accessibility is improved, but communication reliability deteriorates due to blocked or misrouted inbound communications

Engineering Contradiction:
Improveaddress accessibilityVSAvoidcommunication reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces a relay server as an intermediary component that mediates communications between endpoint devices behind NATs and external devices. The relay server receives probing packets from external devices, forwards them to the appropriate endpoint devices, and relays responses back, thereby enabling reliable inbound communication without requiring changes to the NAT devices themselves.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements a probing mechanism where endpoint devices send probing packets to the relay server in advance to obtain address and port assignments before actual communication occurs. This preliminary action allows the system to establish communication paths and assess network characteristics (bandwidth, latency, jitter) before real data transmission, ensuring reliable communication setup.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If probing packets are sent to determine network characteristics, then communication reliability is improved, but network traffic and processing overhead increase

Engineering Contradiction:
Improvecommunication reliabilityVSAvoidnetwork traffic
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The probing packets serve multiple functions simultaneously: they establish communication paths through the relay server, obtain address and port assignments, assess network characteristics (bandwidth, latency, jitter), and trigger relay server responses. This multi-functionality reduces the need for separate signaling and measurement messages, thereby minimizing overall network traffic while achieving reliable communication setup.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2896160B1Bandwidth probing messages
Publication Date: 2016.06.29 CISCO TECHNOLOGY INC
  • EP2896160B1 patent drawingFigure 1
  • EP2896160B1 patent drawingFigure 2
  • EP2896160B1 patent drawingFigure 3

AI summary

Techniques are provided for detecting network characteristics. At a first endpoint device configured to communicate with a second endpoint device in a network, a request is made to a relay server in a network for an address and port assignment on the relay server. The address and port assignment are obtained from the relay server, and a probing packet is sent at a first time instance to the relay server at an address and port corresponding to the address and port assignment. The first time instance is stored in a timestamp field of the probing packet. A response packet responsive to the probing packet is then received from the address and port on the relay server at a second time instance. The second time instance is stored in a timestamp field of the response packet.