Active-Active Edge NAT Routing for Scalable North-South Traffic
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Solution Overview
Problem
Existing logical networks in datacenters face bottlenecks due to active-standby configurations of edge nodes, which limit the scalability and efficiency of network address translation (NAT) in handling large volumes of 'north-south' traffic, particularly for services like VPN and DNS, leading to management challenges with numerous connections.
Innovation Solution
Implementing network address translation (NAT) at edge nodes in an active-active configuration, where NAT entries redirect outgoing data messages to the correct interface by modifying the source MAC address, ensuring efficient load balancing and reducing the need for additional routing table entries, even when default routes direct traffic to a single edge node.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an active-standby configuration is used for edge nodes, then service reliability is improved, but traffic handling capacity deteriorates due to bottlenecks at the single active node
Solution Approach 1:
The system dynamically switches between active-standby and active-active configurations based on traffic conditions. During normal operation, multiple edge nodes share traffic in active-active mode for high throughput. When failures occur or services require stateful processing, the system transitions to active-standby mode to ensure reliability, thus adapting the configuration dynamically to meet changing requirements.
Solution Approach 2:
The patent changes the operational parameter of edge nodes from static (either always active-standby or always active-active) to variable, allowing the system to adjust the number of active nodes based on traffic volume and service requirements. This parameter change enables the system to optimize between reliability and productivity by selecting the appropriate configuration mode.
2Productivity
If an active-active configuration is used to split traffic among multiple edge nodes, then traffic handling capacity is improved, but routing complexity increases due to default routes directing traffic to a single node
Solution Approach 1:
The patent extracts the routing decision logic from the default route configuration and places it in the NAT table. Instead of relying on complex routing table entries to direct traffic to the correct edge node, the system uses NAT entries that are already distributed across edge nodes to make routing decisions, thereby simplifying the overall routing complexity while maintaining active-active traffic distribution.
Solution Approach 2:
The NAT table acts as an intermediary between the incoming traffic and the edge node routing. Rather than requiring direct routing table entries for each external address, the NAT entries serve as a mediator that redirects traffic to the appropriate edge node based on the connection state, reducing routing complexity while enabling efficient traffic distribution.
3Manufacturing precision
If routing table entries are generated for each connection to redirect traffic to the correct edge node, then traffic routing accuracy is improved, but management complexity increases when the number of connections is large
Solution Approach 1:
The patent merges the routing information with the NAT entry information. Instead of maintaining separate routing table entries for each connection, the system combines the NAT translation information with the routing decision in a single NAT table entry. This consolidation maintains precise traffic routing to the correct edge node while significantly reducing management complexity by eliminating the need for separate routing entries.
Solution Approach 2:
The NAT table entry serves multiple functions simultaneously: it performs address translation, maintains connection state, and directs routing to the appropriate edge node. This multi-functionality eliminates the need for separate routing table entries, achieving both accurate traffic routing and simplified management even when handling large numbers of connections.
4Stability of the object's composition
If a single edge node handles all north-south traffic, then service state consistency is improved, but scalability deteriorates for networks with large traffic volumes
Solution Approach 1:
The system performs preliminary actions by pre-distributing connection state information across multiple edge nodes before traffic arrives. When a connection is established at one edge node, the NAT entry and connection state are proactively distributed to other edge nodes in the cluster. This preliminary distribution of state information enables multiple nodes to handle traffic for the same connection, improving scalability while maintaining service state consistency through pre-established knowledge of connection ownership.
Data Source
AI summary
Some embodiments provide a method for forwarding data messages at multiple edge gateways of a logical network that process data messages between the logical network and an external network. At a first edge gateway, the method receives a data message, having an external address as a destination address, from the logical network. Based on the destination address, the method applies a default route to the data message that routes the data message to a second edge gateway and specifies a first output interface of the first edge gateway for the data message. After routing the data message, the method applies a stored NAT entry that (i) modifies a source address of the data message to be a public NAT address associated with the first edge gateway and (ii) redirects the modified data message to a second output interface of the first edge gateway instead of the first output interface.