PE Router B-MAC Lookup for Active-Active PBB-EVPN Redundancy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In Provider Backbone Bridging (PBB) Ethernet Virtual Private Networks (EVPN), PE routers conventionally drop known unicast traffic if they have not learned the destination Customer-MAC (C-MAC) address and are not the designated forwarder (DF) for the Ethernet Segment, leading to packet loss and network inefficiency.
Innovation Solution
PE routers are configured to perform an additional lookup in their B-MAC table to determine if the destination B-MAC address matches a B-MAC included in their table, allowing them to forward network packets even if the destination C-MAC address has not been learned, thereby avoiding packet drop and enabling path forwarding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PE routers operate in active-active mode with all PE routers forwarding traffic, then network redundancy and load balancing are improved, but packet loss occurs when a PE router has not learned the destination C-MAC address and is not the designated forwarder
Solution Approach 1:
The patent applies preliminary action by performing a B-MAC table lookup before dropping packets. When a PE router receives a known unicast packet for a C-MAC address it has not learned, it first checks whether the destination B-MAC address is in its B-MAC table. If found, the router forwards the packet using the associated egress interface before MAC learning can occur, preventing packet loss in advance.
2Device complexity
If PE routers drop unknown unicast traffic when not the designated forwarder, then traffic forwarding control is simplified, but network convergence speed deteriorates
Solution Approach 1:
The patent segments the forwarding decision process into two independent lookup stages: first checking the B-MAC table for backbone MAC address matches, then falling back to conventional C-MAC table lookup. This segmentation allows PE routers to quickly forward packets using B-MAC information without waiting for C-MAC learning, thereby accelerating network convergence while maintaining forwarding control.
3Measurement precision
If PE routers perform additional B-MAC table lookup before forwarding, then packet forwarding accuracy is improved, but processing complexity increases
Solution Approach 1:
The B-MAC table lookup is performed as a preliminary action in the packet forwarding path. The patent integrates this lookup early in the forwarding decision process, before packets would be dropped due to unknown C-MAC addresses. This preliminary check ensures high forwarding accuracy by utilizing already-available B-MAC routing information without requiring complex additional processing.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
In one example, a method includes configuring a first provider edge (PE) router of a Provider Backbone Bridging (PBB) Ethernet Virtual Private Network (EVPN) to join an Ethernet Segment in active-active mode with at least a second PE router that is operating as a designated forwarder for the Ethernet Segment; receiving, by the first PE router from a remote PE router and prior to the first PE router performing Media Access Control (MAC) learning of a customer-MAC (C-MAC) address that is reachable via a backbone-MAC (B-MAC) address associated with the Ethernet Segment, a network packet that includes the C-MAC address; and in response to determining that the C-MAC address has not been learned by the first PE router and the B-MAC address included in the network packet is associated with the Ethernet Segment, forwarding, by the first PE router, the network packet to a destination identified by the C-MAC address.