Egress Node Protection Labels for BUM Traffic Black-Holing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In Ethernet Virtual Private Networks (EVPN), node failures can lead to traffic black-holing during the global repair process, as backup designated forwarders (DF) do not immediately take over forwarding BUM traffic, resulting in packet loss and performance degradation.
Innovation Solution
Implementing egress node protection labels, where PE devices advertise labels indicating which egress PE devices they protect, allowing the ingress PE device to send BUM packets with these labels, enabling backup DFs to forward traffic even before transitioning to the new DF through global repair, thus reducing traffic black-holing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the backup designated forwarder waits for global repair completion before forwarding BUM traffic, then the DF election process maintains proper protocol sequencing, but traffic black-holing occurs during the repair period
Solution Approach 1:
The patent applies preliminary action by enabling the backup DF to forward BUM traffic before the global repair process completes. The backup DF proactively starts forwarding traffic in advance of the formal DF transition, eliminating the waiting period and preventing traffic black-holing during the handover period.
Solution Approach 2:
The patent applies preliminary anti-action by having the backup DF counteract the potential traffic loss before it occurs. By implementing protective forwarding behavior in advance of the actual DF election completion, the system prevents the harmful effect of traffic black-holing rather than reacting to it after the fact.
2Productivity
If the backup DF immediately forwards BUM traffic upon DF failure detection, then traffic loss is minimized, but incorrect forwarding may occur before proper DF election
Solution Approach 1:
The patent uses the BDF label as an intermediary mechanism to enable the backup DF to forward traffic safely. The label acts as a credential that authorizes the backup DF to forward BUM traffic without causing incorrect forwarding, as it is only valid for the specific protected DF and Ethernet segment identifier combination.
Solution Approach 2:
The patent applies parameter changes by introducing the BDF label as a new parameter that changes the forwarding behavior of the backup DF. This label parameter enables the backup DF to distinguish between traffic it should forward (with the matching BDF label) and traffic it should not forward, thereby maintaining forwarding accuracy while improving productivity.
3Reliability
If egress PE devices process BUM packets with BDF labels through control plane, then forwarding accuracy is ensured, but processing overhead increases
Solution Approach 1:
The patent applies segmentation by dividing the forwarding decision process into two paths: standard forwarding for regular traffic and BDF label-matching forwarding for protected traffic. This segmentation allows the control plane to handle only the specific case of BDF label verification, reducing the overall processing load while maintaining accuracy for the critical protected traffic path.
Data Source
AI summary
Techniques are described for facilitating node protection for Broadcast, unknown Unicast, and Multicast (BUM) traffic for a multi-homed node failure. For example, multi-homed provider edge (PE) devices each advertise egress node protection labels to an ingress PE device. In the event one of the multi-homed PE devices fails, the ingress PE device sends a BUM packet including the egress node protection labels for the failed node. When an egress PE device receives the BUM packet, the egress PE device determines whether the BUM packet includes the egress node protection labels and whether the egress PE device is operating as a backup designated forwarder (DF) on an Ethernet segment identifier (ESI) for which the failed node was the DF. If the BUM packet includes the egress node protection labels and the egress PE device is operating as a backup DF, the egress PE device forwards the BUM traffic to the ESI.