PBB-EVPN PE Router C-MAC Learning to Reduce BUM Flooding
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Solution Overview
Problem
In PBB-EVPN networks, asymmetric MAC learning leads to inefficiencies and unnecessary traffic flooding due to remote PE routers not learning C-MAC addresses, resulting in increased BUM traffic and resource wastage.
Innovation Solution
A first PE router sends an extended community for a B-MAC route via BGP to inform remote PE routers of C-MAC address reachability, allowing them to learn and forward unicast traffic instead of broadcasting it to all devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If PBB-EVPN uses data-plane learning for remote C-MAC to remote B-MAC binding, then MAC address scalability is improved, but asymmetric MAC learning occurs causing traffic flooding
Solution Approach 1:
The patent applies preliminary action by having the local PE router proactively send L2 control messages to remote PE routers to pre-populate their forwarding tables with C-MAC to B-MAC bindings. This preliminary population of forwarding information prevents asymmetric MAC learning and eliminates the need for traffic flooding when packets arrive at remote PEs.
2Use of energy by moving object
If remote PE routers do not learn C-MAC addresses, then resource consumption is reduced, but BUM traffic increases due to inability to forward unicast traffic
Solution Approach 1:
The patent extracts only the necessary C-MAC to B-MAC binding information from the local PE router and sends it selectively to remote PE routers that need it for forwarding. This selective extraction and distribution of forwarding information allows remote PEs to forward unicast traffic without learning all C-MAC addresses, thus reducing resource consumption while avoiding BUM traffic.
3Object-generated harmful factors
If L2 control messages are sent to populate forwarding tables, then traffic flooding is avoided, but control plane overhead increases
Solution Approach 1:
The patent applies partial action by sending L2 control messages only to remote PE routers that require C-MAC forwarding information, rather than to all PEs in the network. This partial distribution of control information avoids unnecessary control plane overhead while still preventing traffic flooding at the specific remote PEs that need the forwarding bindings.
Data Source
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AI summary
In one example, a method includes performing L2 learning of a C-MAC address included in a first L2 data message by a first provider edge (PE) router included in an Ethernet Segment of a Provider-Backbone Bridging Ethernet Virtual Private Network (PBB-EVPN); sending to a second PE router within the Ethernet Segment an L2 control message comprising the C-MAC address and a B-MAC address corresponding to the Ethernet Segment of the PBB-EVPN, wherein the L2 control message informs the second PE router of the reachability of the C-MAC address through the first PE router; receiving, by the first PE router and from the second PE router, a second L2 data message as unicast traffic destined for the C-MAC address; and forwarding the second L2 data message to the first CE router.