Edge Device Anti-Loop Control via DF State Calculation
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Solution Overview
Problem
In EVPN networks, redundant edge devices can generate loops if anti-loop measures are not implemented, leading to communication difficulties and potential attacks on bandwidth by malicious users, making it challenging for the network provider to prevent loop generation within their area of responsibility.
Innovation Solution
The edge device implements anti-loop measures by closing one port at the responsibility demarcation point, using an access port and an EVPN function unit to calculate the Designated Forwarder (DF) or Backup DF state, and physically opening or closing the port based on the calculation results to prevent loop generation while ensuring connection normality with the NW user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant edge devices are configured without anti-loop measures, then device redundancy and connection normality are improved, but loop generation occurs causing communication failure
Solution Approach 1:
The patent applies preliminary action by closing the access port before the DF state is determined during device startup. This prevents loop generation in advance while the device is still establishing its forwarding state, ensuring that when the port is opened later, no loop will occur. The control unit closes the access port upon detecting link-up in an undefined DF state, performs DF calculation, and only opens the port after confirming DF status, thereby preventing loops before they can form.
2Object-generated harmful factors
If anti-loop measures such as LAG are implemented, then loop generation is prevented, but device complexity and configuration difficulty increase
Solution Approach 1:
The patent implements self-service by enabling the edge device to automatically perform DF state calculation and access port control without requiring manual LAG configuration. The control unit autonomously calculates the DF state using EVPN protocols, determines whether to open or close the access port based on the calculation result, and manages the port state accordingly. This eliminates the need for complex manual anti-loop configurations while maintaining loop prevention.
3Speed
If the access port remains open during DF state calculation, then connection responsiveness is improved, but loop generation risk increases
Solution Approach 1:
The patent applies preliminary action by closing the access port before DF state calculation is complete, preventing loop generation during the vulnerable period when the DF state is undefined. The control unit closes the port upon detecting link-up in an undefined state, maintains it closed during calculation, and only opens it after confirming DF status. This ensures connection responsiveness is maintained through rapid automated control while eliminating loop risks during the calculation process.
Data Source
AI summary
An object of the present invention is to provide an edge device, a control method, and a program with which the effects of loop generation can be minimized from the NW operator side while ensuring connection normality with the device of an NW user. An edge device according to the present invention physically closes an access port upon confirmation that the access port has been connected to an external device while the access port is in a physically released state and a DF state is undefined, notifies other edge devices within an EVPN MH configuration that the host device has entered a state in which the host device may become the DF and causes an EVPN function unit to calculate the DF state to be set, physically opens the access port when the calculation result indicates DF, and physically closes the access port when the calculation result indicates BDF.