Managed Forwarding Element Bridge Across Datacenters
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Solution Overview
Problem
Existing bridging techniques are limited to connecting logical L2 networks within a single datacenter, and there is a need for a method to bridge logical L2 networks across multiple datacenters with physical L2 networks, while avoiding traffic loops and undesired connectivity between datacenters.
Innovation Solution
A method that involves a network manager providing a bridge configuration to central controllers, which select and configure managed forwarding elements in each datacenter to bridge packets between logical and physical L2 networks, using a generic physical network identifier that maps to specific networks at each datacenter, and employing a tunnel encapsulation header to prevent re-bridging of already bridged packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bridging is used to connect logical L2 networks across multiple datacenters, then network connectivity is improved, but traffic loops and undesired connectivity between datacenters may occur
Solution Approach 1:
The patent segments the bridging function by implementing separate bridge instances in each datacenter rather than a single distributed bridge. Each bridge instance operates independently within its local datacenter, processing only locally-generated traffic. This segmentation prevents traffic loops by ensuring that bridging operations are localized and do not create unintended connectivity paths between datacenters.
2Ease of operation
If a single bridge configuration is distributed to multiple datacenters, then configuration simplicity is improved, but incorrect packet handling and re-bridging issues occur
Solution Approach 1:
The patent applies local quality by making each datacenter's bridge instance locally-aware of its environment. Each bridge instance is configured with datacenter-specific parameters and operates independently, making decisions based on local conditions rather than following a uniform configuration. This ensures reliable packet handling by preventing re-bridging of already-processed packets and ensuring correct local network behavior.
3Reliability
If bridging is limited to single datacenter, then traffic loop prevention is improved, but multi-datacenter connectivity is lost
Solution Approach 1:
The patent introduces an intermediary mechanism where each datacenter's bridge instance acts as an independent mediator for local traffic. Rather than allowing direct end-to-end bridging across datacenters, each instance mediates traffic locally and prevents it from being forwarded to other datacenters. This intermediary approach maintains traffic loop prevention while enabling controlled multi-datacenter connectivity through other means (such as routing or overlay networks).
Data Source
AI summary
Some embodiments provide a method for a set of central controllers that manages forwarding elements operating in a plurality of datacenters. The method receives a configuration for a bridge between (i) a logical L2 network that spans at least two datacenters and (ii) a physical L2 network. The configuration specifies a particular one of the datacenters for implementation of the bridge. The method identifies multiple managed forwarding elements that implement the logical L2 network and are operating in the particular datacenter. The method selects one of the identified managed forwarding elements to implement the bridge. The method distributes bridge configuration data to the selected managed forwarding element.