Nexthop-to-Transport Mapping in DMVPN via BGP

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Solution Overview

Problem

Current Dynamic Multipoint VPN (DMVPN) schemes face network bottlenecks and complexity due to the requirement of Internet Protocol (IP) routing peering and the use of Next Hop Resolution Protocol (NHRP), especially in large networks, where selecting the correct link for tunneled packets is challenging without routing information exchange with Internet Service Providers (ISPs).

Innovation Solution

A method is provided to configure nexthop-to-transport mappings using Border Gateway Protocol (BGP) for VPN forwarding, allowing dynamic exchange of nexthop-to-transport mapping information along with routing information, eliminating the need for static mappings and reducing network complexity by using BGP as a routing protocol to advertise these mappings across all sites.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If NHRP is used for nexthop resolution in DMVPN, then nexthop to transport mapping is achieved, but network bottleneck occurs in large networks

Engineering Contradiction:

Improvenexthop resolutionVSAvoidnetwork throughput

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent extracts the nexthop resolution function from the central NHRP server and distributes it to border routers through BGP routing updates. Each border router independently resolves nexthop addresses using routing information from its RIB, eliminating the single point of congestion and improving overall network throughput while maintaining ease of operation.

Inventive Principle:

Principle #2Taking out (Extraction)

2Adaptability or versatility

If multiple routing protocols are used for VPN control, then routing flexibility is improved, but implementation complexity increases

Engineering Contradiction:

Improverouting flexibilityVSAvoidprotocol complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent merges the VPN routing control function into a single BGP protocol framework, consolidating what would otherwise require multiple specialized routing protocols. BGP handles both standard routing and VPN-specific nexthop resolution, reducing implementation complexity while maintaining routing flexibility through BGP's inherent path selection and policy routing capabilities.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If DMVPN without ISP routing exchange is used, then VPN privacy is maintained, but transport address selection becomes difficult

Engineering Contradiction:

ImproveVPN privacyVSAvoidtransport address selection

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent introduces BGP as an intermediary protocol that enables transport address selection without direct routing information exchange with ISPs. Border routers use BGP to receive routing updates containing nexthop-to-transport mappings, allowing them to select appropriate transport addresses while maintaining VPN privacy by not sharing internal routing information with external ISPs.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10361884B2Virtual private network forwarding and nexthop to transport mapping scheme

Publication Date: 2019.07.23 CISCO TECHNOLOGY INC

AI summary

A method is provided in one example embodiment and includes configuring on a network element a first tunnel from the network element to a first network, wherein the configuring comprises mapping a nexthop address of the local network element to a transport address of the tunnel on the network to create a first nexthop-to-transport mapping for the network element; and advertising the first nexthop-to-transport mapping along with routing information for the network element to remote network elements.