Logical Router Egress Selection Using Local Preference Attributes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In multi-site computing environments, existing methods for advertising the preferred egress point for logical routers across edge nodes are inefficient, requiring numerous routing protocol instances and sessions, leading to increased complexity and potential instability when the preferred egress point goes down or comes back online.
Innovation Solution
Implementing a routing protocol that uses universally unique identifiers (UUIDs) to advertise the preferred egress point among edge nodes, with a single virtual routing and forwarding (VRF) table, and employing a local preference attribute based on timing information to prevent the original preferred egress point from reclaiming its status when it returns online.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a routing instance for each service router is used to distribute the default route, then the preferred egress point can be communicated to other service routers, but the number of routing protocol instances and sessions increases significantly
Solution Approach 1:
The patent merges the routing information for multiple service routers into a single routing instance. Instead of creating separate routing instances for each service router, the system uses one routing instance that advertises multiple default routes with different next-hop IP addresses corresponding to different service routers. This consolidation reduces the number of routing protocol instances from thousands to a manageable number, directly resolving the contradiction between reliable egress point communication and system complexity.
2Ease of operation
If the preferred egress point is designated centrally, then centralized services can always be performed at the same point, but the system becomes unstable when the preferred egress point goes down or comes back online
Solution Approach 1:
The patent implements dynamic route selection by advertising multiple default routes with different local preference values. When the preferred egress point goes down, the system automatically transitions to an alternative service router by selecting the route with the next highest local preference. This dynamic adaptability maintains system stability while preserving centralized service performance, as the failover is automatic and transparent to the centralized services themselves.
Solution Approach 2:
The system uses local preference attributes as a feedback mechanism to indicate the status and priority of different service routers. By adjusting local preference values based on the operational status and timing information, the system provides feedback that guides route selection. This feedback loop ensures that traffic is automatically directed to healthy service routers while preventing flapping when routers come back online, thus maintaining stability.
3Loss of information
If multiple routing sessions are established to communicate the preferred egress point, then complete routing information can be distributed, but the processing overhead and potential instability increase
Solution Approach 1:
The patent makes the single routing instance universal by enabling it to advertise multiple default routes serving different service routers. This single routing instance performs the function that previously required multiple separate routing instances, conveying complete routing information for all service routers through one instance. This multi-functionality approach reduces processing overhead while maintaining complete routing information distribution.
Data Source
AI summary
In some embodiments, a method for selecting an egress point for accessing an external network associated with a distributed logical router that is distributed across at least a first computing device and a second computing device is provided. The method receives, by an instance of the logical router at the first computing device, first identification information and a first preference value. The method compares the first preference value to a second preference value. The second preference value is associated with second identification information corresponding to a current computing device that is identified as a current preferred egress point for the logical router. The method determines whether to set the egress point connected to the instance of the logical router in the second computing device as a new preferred egress point for the logical router.