US Patent 10469361 Loop prevention for EVPN and PBB-EVPN

In general, techniques are described for reducing forwarding loops for layer (L2) traffic that traverses an EVPN or PBB-EVPN instance (EVI) by deterministically determining an access-facing logical interface to block from respective access-facing logical interfaces of PE devices that switch the L2 traffic using the EVI. A provider edge (PE) network device may detect an L2 forwarding loop on an L2 forwarding path that includes the access-facing logical interface. In response to detecting an L2 forwarding loop and based at least on comparing an identifier for the local PE device and an identifier for a remote PE device that implements the EVPN instance, the PE device may block the access-facing logical interface to block L2 traffic from the local customer network.