Core Edge Node Single-Flow-Active VLAN Forwarding
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Solution Overview
Problem
Existing EVPN multi-homing mechanisms, such as single-active and all-active modes, are insufficient to support access Layer 2 gateway protocols like MSTAG, REPAG, and ERPS, as they fail to ensure that only one core edge node actively handles a VLAN flow, leading to potential duplicate packets and loop issues.
Innovation Solution
The introduction of a single-flow-active mechanism, where a VLAN is active on multiple core edge nodes but only one flow is active at a time, with designated forwarder election on a per-flow basis, and loop prevention handled by the access node, enhancing support for Layer 2 gateway protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If single-active or all-active EVPN multi-homing mechanisms are used, then core edge nodes can handle VLAN flows, but duplicate packets and loop issues occur because multiple core edge nodes actively handle the same VLAN flow
Solution Approach 1:
The patent segments the VLAN flow handling by introducing per-flow designated forwarder election, where each VLAN flow is assigned to a specific core edge node. This segmentation prevents multiple core edge nodes from actively handling the same VLAN flow, thereby eliminating duplicate packets and loops while maintaining support for Layer 2 gateway protocols.
Solution Approach 2:
The patent implements dynamic designated forwarder election based on per-flow basis, allowing the active core edge node to change dynamically based on flow characteristics and network conditions. This dynamic approach enables reliable packet forwarding without duplication while adapting to different Layer 2 gateway protocol requirements.
2Reliability
If only one core edge node is designated as active for a VLAN flow, then loops and duplicate packets are prevented, but network redundancy and failover capability are reduced
Solution Approach 1:
The patent implements preliminary designated forwarder election before VLAN flow processing, where core edge nodes are pre-designated as forwarders based on per-flow criteria. This preliminary action establishes clear packet forwarding paths that prevent loops and duplicates, while the election mechanism itself is designed to enable smooth failover to backup forwarders when needed.
Solution Approach 2:
The patent incorporates feedback mechanisms where core edge nodes monitor the status and performance of designated forwarders. When a designated forwarder fails or performance degrades, the feedback triggers re-election of a new designated forwarder, enabling dynamic rerouting while maintaining the single-active constraint that prevents duplicate packets and loops.
Data Source
AI summary
In one embodiment, a method according to the present disclosure includes receiving a topology change advertisement at a remote core edge node and performing a network address information removal operation. The topology change advertisement is received from a core edge node that is in communication with an access network. The topology change advertisement indicates that a topology change has occurred in the access network. The network address information removal operation removes network address information stored by the remote core edge node. The network address information is used by the remote core edge node in participating in communications with the core edge node.