Loop Avoidance in EVPN PE Devices via Identifier Tracking
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Solution Overview
Problem
In Ethernet virtual private networks (EVPN) with an active-active mode, dual-homed devices can experience data packet loops when interfaces between PE devices and CE devices are faulty, leading to network resource waste and performance issues.
Innovation Solution
A method where a PE device sends a specific identifier to another PE device, determines if its associated interface with the CE device is faulty, and avoids sending data packets back through that interface, using a new SRv6-VPN SID attribute to prevent loop formation by discarding or rerouting packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PE devices operate in active-active mode to improve network redundancy and reliability, then network reliability is improved, but loop problems occur when interfaces to CE devices are faulty
Solution Approach 1:
The patent applies preliminary action by pre-configuring fallback paths and loop detection mechanisms before faults occur. PE devices pre-establish alternative routing paths and implement proactive loop detection through identifier tracking, so when interface faults occur, the system can immediately switch to fallback paths without forming loops.
Solution Approach 2:
The patent uses an intermediary approach by introducing a loop avoidance mechanism that acts as a mediator between PE devices. This mechanism tracks packet identifiers and intervenes when potential loops are detected, preventing harmful loop formation while maintaining active-active operation benefits.
2Productivity
If PE devices forward traffic through multiple paths to improve network throughput and resource utilization, then productivity is improved, but transmission loops form when interfaces are faulty
Solution Approach 1:
The patent implements feedback by having PE devices monitor and track packet identifiers as they traverse the network. When a packet is detected circulating in a loop (identified by recognizing its own identifier), the system provides feedback to stop further forwarding, eliminating wasted transmission time while allowing multiple paths for normal traffic.
3Ease of operation
If PE devices use simplified forwarding rules to improve ease of operation, then ease of operation is improved, but loop detection and prevention becomes difficult
Solution Approach 1:
The patent extracts loop detection functionality from complex forwarding logic by using a separate identifier tracking mechanism. PE devices maintain simple forwarding rules for normal operation but independently track packet identifiers to detect loops, separating these concerns and maintaining ease of operation while enabling effective loop detection.
Data Source
AI summary
In a loop avoidance communications method, a first provider edge (PE) device sends a first identifier to a second PE device through a first interface; the first PE device receives, from the second PE through the first interface, a data packet including the first identifier. Then, the first PE device determines that a second interface associated with the first identifier is in a faulty state. In response to determining that the second interface is in the faulty state, the first PE device avoids sending the data packet to the second PE device through the first interface. The first PE device connects to a customer edge (CE) device using the second interface.