Hi Christian,Discontinuous mask for IPv6 was supported in IOS-XR in release 5.2.2.You can refer below link for details:https://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/ip-addresses/command/reference/b-ip-addresses-cr-asr9000/b-ipaddr-cr-asr9k_chapter_01.html#wp4831598620