Specifically, like in an IPv4 community, BIER can do the job over L2 hyperlinks specifically or around tunnels. Zheng Zhang, Bo Wu, Zhaohui Zhang, IJsbrand Wijnands, Yisong Liu, Hooman Bidgoli, 2022-07-03, This document defines a BIER proxy functionality to aid a solitary BIER sub-area above multiple underlay routing protocol regions (Autonomous Systems or IGP locations).