BNG Logical Port Hold-Down During Subscriber Reprogramming
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Solution Overview
Problem
In broadband network gateways, when a user plane subscriber access device reboots due to hardware or software failure, it prematurely indicates to the access network that a logical port is active, leading to subscriber traffic blackholing as it cannot handle traffic before all subscribers are programmed, causing significant loss of data.
Innovation Solution
The broadband network gateway control plane device holds down the logical port state transition to active until all subscribers are fully programmed, using a keep-down flag to prevent the access network from sending traffic until programming is complete, thereby ensuring the device can handle subscriber traffic appropriately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the user plane subscriber access device reboots and immediately indicates logical port active state, then the device can quickly restore service, but subscriber traffic blackholing occurs because the device cannot handle traffic before programming is complete
Solution Approach 1:
The system performs preliminary programming of all subscriber information before activating the logical port. The BNG-CP device completes the programming of all subscribers in the SGRP to the BNG-UP device before allowing the logical port to transition to active state, ensuring the device is fully prepared to handle traffic without blackholing.
Solution Approach 2:
The system implements a feedback mechanism where the BNG-UP device notifies the BNG-CP device when programming is complete, and the BNG-CP device subsequently notifies the access network. This feedback loop ensures that the logical port only becomes active after all necessary programming operations are finished, coordinating the activation sequence to prevent traffic blackholing.
2Stability of the object's composition
If the logical port transitions to active state immediately after reboot, then network availability is improved, but data loss occurs due to traffic blackholing
Solution Approach 1:
All subscriber programming operations are completed as a preliminary action before the logical port transitions to active state. The system ensures that every subscriber in the SGRP is fully programmed into the BNG-UP device before service restoration begins, eliminating the window where traffic blackholing could occur.
Solution Approach 2:
The system applies preliminary anti-action by blocking the logical port from transitioning to active state until programming is complete. The BNG-CP device withholds the active state notification to the access network until it receives confirmation that all subscribers are programmed, preventing the harmful effect of traffic blackholing before it can occur.
3Reliability
If the device waits for complete programming before indicating active state, then traffic blackholing is prevented, but service restoration time increases
Solution Approach 1:
The system performs all necessary subscriber programming operations as preliminary actions during the reboot process, so that when the logical port needs to become active, all programming is already complete. This eliminates delays between activation and traffic handling capability.
Solution Approach 2:
The programming operations continue uninterrupted during the reboot process, and the logical port transition to active state follows immediately upon completion. This continuous process minimizes the total time from reboot to full service restoration while ensuring reliability.
Data Source
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AI summary
In some implementations, a network device may receive an indication that a user plane subscriber access device has rebooted. The network device may transmit based on the indication that the user plane subscriber access device has rebooted, an indication to refrain from notifying an access network that a logical port corresponding to a subscriber group created in a track-logical-port mode is associated with an active state. It is intended that, when published, the abstract be accompanied by Figure 1.