Hi Irene, You can adjust the linux source port range in /proc/sys/net/ipv4/ip_local_port_range to be IANA compliant. “BFD packets are sent with a dynamic source port number. Linux systems use by default a bit different dynamic port range than the IANA approved one (49152-65535). If you experience problems with compatibility, please adjust /proc/sys/net/ipv4/ip_local_port_range.” (from https://bird.network.cz/?get_doc&v=20&f=bird.html#toc6.3) HTH! Johannes From: Bird-users <bird-users-bounces@network.cz> on behalf of Irene Lalioti <irene.lalioti@restena.lu> Date: Tuesday, 10. October 2023 at 11:20 To: Maria Matějka <maria.matejka@nic.cz>, BIRD Users <bird-users@network.cz>, Marian Rychtecky <mr@nix.cz> Subject: Question Verification regarding UDP port of BFD Hello dear Maria, Marian, and BIrd community, I would like to ask you your feedback regarding an issue a member of us has indicated. That member has stumbled upon a non-RFC compliant BFD source port with result their CISCO router to drop the BFD packets. Is it that Bird does not or does change the code to use a different source port? We would need to see how to workaround this issue. Předem moc děkuji!! Hesky den! Irene -- Irene Lalioti Network Engineer Fondation RESTENA 2, avenue de l'Université L-4365 Esch/Alzette Tel: +352 424409 1 Fax: +352 422473 This email may contain information for limited distribution only, please treat accordingly.