RFC 9541: Flush Mechanism for Customer MAC Addresses Based on Service Instance Identifier (I-SID) in Provider Backbone Bridging EVPN (PBB-EVPN)

Provider Backbone Bridging (PBB) can be combined with Ethernet Virtual Private Networks (EVPNs) to deploy Ethernet Local Area Network (E-LAN) services in large Multiprotocol Label Switching (MPLS) networks. That combination is what we refer to as "PBB-EVPN." Single-Active multihoming and per Service Instance Identifier (I-SID) load-balancing can be provided to access devices and aggregation networks. In order to speed up the network convergence in case of failures on Single-Active multihomed Ethernet Segments (ESs), PBB-EVPN defines a flush mechanism for Customer MACs (C-MACs) called "C-MAC flush" that works for different Ethernet Segment Backbone MAC (B-MAC) address allocation models. This document complements those C-MAC flush procedures for cases in which no PBB-EVPN ESs are defined (i.e., the attachment circuit is associated with a zero Ethernet Segment Identifier (ESI)) and the C-MAC flush requires I-SID-level granularity.