PBB PE MAC Flushing for Black-Hole Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In provider backbone bridging networks, dual-homing configurations lead to black-holing of traffic when links or PBB PE devices fail, causing disruptions due to reliance on aging or new packet transmission for learning new CMAC-to-BMAC associations.
Innovation Solution
Implementing a method to flush CMAC-to-BMAC associations at PBB PE devices using Label Distribution Protocol (LDP) messaging or a combination of Spanning Tree Protocol (STP) Topology Change Notification (TCN) messaging and LDP, triggering a faster learning of new associations reflective of secondary traffic paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CMAC-to-BMAC associations are learned through native Ethernet learning process, then traffic forwarding is maintained, but traffic black-holing occurs after link failure until associations are aged out or new packets trigger re-learning
Solution Approach 1:
The patent applies preliminary action by proactively flushing CMAC-to-BMAC associations from FIBs when a link failure is detected, rather than waiting for natural aging or new packets to trigger re-learning. This preliminary flushing action initiates the re-learning process immediately, preventing the black-holing period and ensuring faster restoration of traffic forwarding through the secondary path.
2Productivity
If CMAC-to-BMAC associations are retained in FIBs, then traffic forwarding continues, but failed paths continue to be used causing black-holing
Solution Approach 1:
The patent implements feedback by monitoring link status and using this feedback to trigger association flushing when failures are detected. The system continuously monitors the health of active paths and provides feedback to the forwarding database, which then flushes associations for failed paths, ensuring that only valid paths are used for traffic forwarding and preventing black-holing.
Data Source
AI summary
A technique for operating a network involves controlling the black-holing of traffic by forcing customer source MAC address (CMAC)-to-backbone source MAC address (BMAC) associations at provider backbone bridge (PBB) provider edge (PE) devices to be flushed from their corresponding forwarding information bases (FIBs) in response to a service failure so that new CMAC-to-BMAC associations, which are reflective of a secondary traffic path, are learned faster than they would otherwise be learned if the network had relied on native functionality to learn new CMAC-to-BMAC associations that are reflective of the secondary traffic path.