EVPN-IRB MAC-IPv6 Sync for ToR Traffic Blackhole Prevention
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Solution Overview
Problem
In IPv6-enabled data centers with top-of-rack (ToR) deployments, existing EVPN-IRB solutions face challenges in learning MAC-IPV6 adjacency and MAC sync across redundant ToR switches, leading to potential traffic blackholes due to incomplete neighbor discovery and unsolicited neighbor advertisement processing.
Innovation Solution
A method is implemented where a network node receives unsolicited neighbor discovery (ND) advertisements, updates its cache, syncs this information with multihoming peers, and advertises it to other nodes in the EVPN, ensuring that MAC-IPV6 routes are correctly learned and synced across ToR switches, even in stretched subnets or during host initiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EVPN-IRB solutions use standard neighbor discovery protocols, then protocol compatibility is maintained, but MAC-IPV6 adjacency learning is incomplete causing traffic blackholes
Solution Approach 1:
The patent applies preliminary action by having ToR switches proactively sync MAC-IPV6 adjacency information before actual traffic forwarding is needed. When a ToR switch learns a MAC-IPV6 adjacency through neighbor discovery, it immediately synchronizes this information to peer ToR switches via EVPN control plane messages, ensuring the information is available before any potential traffic blackhole scenario occurs.
Solution Approach 2:
The patent implements feedback mechanisms where ToR switches monitor and track MAC-IPV6 adjacency information synchronization status across the EVPN network. The system continuously exchanges synchronization status information between peer ToR switches, enabling real-time detection and correction of any information asymmetry that could lead to traffic blackholes.
2Reliability
If unsolicited neighbor advertisements are ignored, then protocol standard compliance is maintained, but neighbor information synchronization fails causing routing issues
Solution Approach 1:
The patent applies inversion by reversing the traditional approach to unsolicited neighbor advertisements. Instead of ignoring these non-standard messages as per protocol specifications, the system actively processes and utilizes them as valuable sources of MAC-IPV6 adjacency information. This inverted approach allows the system to extract useful routing information from messages that would normally be discarded.
Solution Approach 2:
The patent enables self-service by allowing ToR switches to autonomously process unsolicited neighbor advertisements and automatically sync the extracted MAC-IPV6 adjacency information to peer switches without requiring external control plane intervention. This self-service mechanism ensures rapid information propagation while maintaining protocol compatibility.
3Reliability
If MAC sync is implemented across redundant ToR switches, then traffic blackholes are prevented, but control plane complexity increases
Solution Approach 1:
The patent applies universality by designing the MAC sync mechanism to handle multiple functions through a single control plane process. The same EVPN control plane infrastructure used for MAC address synchronization is also utilized for IPv6 neighbor discovery information sync, route advertisement, and forwarding state management. This multi-functional approach prevents traffic blackholes while avoiding the need for separate dedicated synchronization protocols.
4Reliability
If all-active multi-homing is implemented, then redundancy is improved, but MAC adjacency synchronization difficulty increases
Solution Approach 1:
The patent introduces an intermediary mechanism where the EVPN control plane acts as a mediator between multiple ToR switches and the end host. Instead of requiring direct peer-to-peer MAC adjacency synchronization between all ToR switches (which would be complex), the control plane intermediates by collecting, validating, and distributing MAC-IPV6 adjacency information to all relevant switches, simplifying the synchronization process while maintaining all-active multi-homing redundancy.
Data Source
AI summary
A method is described and in one embodiment includes receiving at a network node of an Ethernet Virtual Private Network (“EVPN”) an unsolicited neighbor discovery (“ND”) neighbor advertisement (“NA”) message transmitted on behalf of a host; updating an ND cache of the network node with data included in the ND NA message; syncing the received ND NA message to a multihoming peer of the network node; and advertising by the network node the ND NA message to other nodes in the EVPN.