EVPN VTEP Route Aggregation for ASIC Scaling
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Solution Overview
Problem
Symmetric-IRB deployments in EVPN face scaling challenges due to the limited size of ASIC routing tables, as the number of routes each VTEP can hold is proportional to the number of hosts in the VxLAN, leading to hardware limitations and inefficient routing optimizations, especially in data center environments with heavy east-west traffic.
Innovation Solution
A system that aggregates host routes by configuring prefix routes for subnets based on predetermined thresholds, replacing multiple host routes with a single prefix route to optimize the number of routes stored in the ASIC, ensuring efficient routing without traffic loss and accommodating changes in host configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Symmetric-IRB is used to reduce VNI configuration complexity, then ease of operation improves, but the number of host routes in ASIC increases leading to hardware limitations
Solution Approach 1:
The patent merges multiple individual host routes into a single aggregate prefix route representing an entire subnet. Instead of maintaining separate routing entries for each host IP address, the system consolidates them into one route entry that covers the whole subnet range, thereby reducing the total number of routes stored in ASIC while preserving routing functionality.
Solution Approach 2:
The patent changes the routing parameter from individual host-specific routes to subnet-level prefix routes. By shifting from granular host route representation to aggregated prefix representation, the system reduces routing table size and ASIC memory requirements while maintaining the ability to route traffic to individual hosts within the subnet.
2Adaptability or versatility
If the number of VTEPs and hosts increases to support larger data centers, then adaptability improves, but routing table size exceeds ASIC capacity
Solution Approach 1:
The patent applies route aggregation to combine multiple host routes into single prefix routes, enabling the network to scale to larger numbers of VTEPs and hosts without proportionally increasing routing table size. This merging approach allows data centers to expand while keeping ASIC routing table capacity within acceptable limits.
3Measurement precision
If individual host routes are maintained for precise routing, then measurement precision improves, but the quantity of routes increases exceeding hardware limits
Solution Approach 1:
The patent merges individual host routes into aggregate prefix routes while preserving routing precision through the use of subnet masks. The aggregation maintains the ability to precisely route to individual hosts by leveraging the hierarchical structure of IP addressing, where the prefix route provides the necessary precision without requiring separate entries for each host.
Solution Approach 2:
The patent changes the routing representation from host-level precision to subnet-level aggregation, using prefix length and subnet mask parameters to maintain routing precision. This parameter change allows the system to achieve the same routing accuracy with fewer route entries by utilizing the existing IP addressing hierarchy.
Data Source
AI summary
One embodiment provides a system which facilitates scaling of routing in an EVPN. During operation, the system determines, in an Ethernet Virtual Private Network (EVPN), a plurality of virtual tunnel endpoints (VTEPs) coupled to a plurality of subnets, wherein a respective subnet includes one or more hosts, wherein a first VTEP is configured with a first number of host routes for a first subnet coupled to a second VTEP, and wherein each of the first number of host routes corresponds to a host residing in the first subnet. Responsive to detecting that a total number of routes configured on the first VTEP exceeds a first predetermined threshold, the system aggregates the first number of host routes by replacing the first number of host routes with a first prefix route which indicates the first subnet.