L2 Services Across Intermediate Networks via BGP Label Distribution
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Solution Overview
Problem
Establishing layer two (L2) connectivity across multiple intermediate networks is challenging, especially when these networks are provided by different service providers, as they often incur significant overhead and cost in maintaining L2 state information for Virtual Private LAN Service (VPLS).
Innovation Solution
The use of an exterior routing protocol like Border Gateway Protocol (BGP) to distribute label information and establish label switched paths (LSPs) across intermediate networks, allowing routers to exchange L2 service information directly and provide end-to-end LSP connectivity without requiring intermediate networks to maintain L2 state information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If VPLS is used to provide transparent L2 connectivity across intermediate networks, then L2 connectivity is achieved, but overhead and cost increase due to storing and managing L2 state information
Solution Approach 1:
The patent extracts the L2 state information storage and management functions from the intermediate networks and relocates them to the provider edge (PE) routers. This allows intermediate networks to simply forward MPLS packets without maintaining VPLS state, thereby reducing their overhead and cost while preserving end-to-end L2 connectivity through the extracted L2 information stored at PE routers.
Solution Approach 2:
The patent introduces MPLS packet encapsulation as an intermediary mechanism. L2 packets are encapsulated in MPLS packets with labels that enable routing through intermediate networks without requiring them to understand or maintain L2 state. This intermediary layer shields intermediate networks from L2 complexity while maintaining connectivity.
2Reliability
If VPLS is deployed across multiple intermediate networks from different service providers, then L2 connectivity is established, but difficulty increases due to lack of VPLS support and unwillingness to incur overhead
Solution Approach 1:
The patent makes the solution universally applicable across different service providers by using standard MPLS protocols that are widely supported. Instead of requiring each intermediate network to implement proprietary VPLS functionality, the solution uses universal MPLS packet forwarding that any service provider can deploy, making multi-provider L2 connectivity achievable without requiring VPLS support at intermediate nodes.
Solution Approach 2:
The patent segments the VPLS functionality into two parts: L2 state information storage and management at PE routers (edge devices), and simple MPLS packet forwarding at intermediate networks. This segmentation allows intermediate networks to participate in L2 connectivity without needing full VPLS capability, reducing the barrier to deployment across multiple service providers.
Data Source
AI summary
A device provides layer two (L2) services between customer networks that are coupled by one or more intermediate computer networks. The device comprises a routing process that receives label information for a label switched path (LSP) through the intermediate networks. The device further comprises a L2 service that receives L2 service information from a device associated with second customer networks. In accordance with the label information, the device transports L2 communications between the first and second customer networks through the one or more intermediate networks. By utilizing label information in this manner, the device may minimize the impact of providing L2 services through the intermediate networks.