OAM Packet Replication for EVPN Active-Active Link Monitoring
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Solution Overview
Problem
In packet-based computer networks, detecting failures in EVPN Active-Active topology within the service/logical-interface level for each link associated with an Ethernet segment is challenging, as existing methods do not effectively monitor all links of an Ethernet segment for OAM packet transmission and fault detection.
Innovation Solution
A multi-homed customer edge (CE) network device replicates OAM packets and forwards them to all network devices on member links of an aggregated Ethernet segment, allowing the routing engine to configure forwarding instructions and detect faults, initiating a designated forwarder election if necessary, thereby ensuring comprehensive monitoring and fault detection across all links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OAM packets are forwarded only through a single designated forwarder in EVPN Active-Active topology, then device complexity is reduced, but fault detection capability deteriorates because not all links are monitored
Solution Approach 1:
The patent segments the OAM packet forwarding function by introducing multiple designated forwarders (one per Ethernet segment) instead of using a single forwarder for all links. This segmentation allows each forwarder to monitor specific links while collectively providing comprehensive fault detection across the entire Active-Active topology, resolving the contradiction between monitoring coverage and system complexity.
Solution Approach 2:
The patent makes the OAM packet forwarding mechanism universal by enabling any PE router in the Active-Active topology to function as a designated forwarder for its connected Ethernet segment. This multi-functionality allows the system to scale fault detection capability without proportionally increasing complexity, as each router can independently perform forwarding duties for its local segment.
2Reliability
If OAM packets are replicated and forwarded to all PE routers in Active-Active topology, then fault detection coverage is improved, but network traffic volume increases
Solution Approach 1:
The patent applies local quality by having each designated forwarder send OAM packets only to PE routers connected to the same Ethernet segment, rather than flooding all OAM packets to all PE routers in the network. This localized forwarding approach ensures comprehensive monitoring coverage while minimizing unnecessary traffic propagation, thus resolving the contradiction between monitoring coverage and traffic volume.
3Reliability
If comprehensive OAM monitoring is implemented across all Ethernet segment links, then network resilience is improved, but response time for failure detection increases due to complex fault analysis
Solution Approach 1:
The patent implements feedback mechanisms where designated forwarders continuously monitor OAM packet delivery status and immediately trigger failure detection and designated forwarder election processes when link failures are detected. This real-time feedback loop enables rapid response to failures while maintaining comprehensive monitoring, resolving the contradiction between network resilience and failure detection time.
Data Source
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AI summary
A method and network device to execute an Ethernet Virtual Private Network (EVPN) protocol to configure the network device to participate as one of a plurality of customer edge (CE) routers that provide an active-active configuration for an Ethernet segment coupling the CE routers to a plurality of provider edge (PE) routers, wherein the processor is configured to determine whether a packet that is to be forwarded is an operations, administration, and management (OAM) packet; in response to determining that the packet comprises an OAM packet, replicate the OAM packet for one or more interface links of an Ethernet segment associated with the CE router; configure forwarding instructions to the one or more interface links of the Ethernet segment associated with the CE router; and forward the OAM packet and the replicated OAM packets to the PE routers.