[BCP180]   Best Current Practice 180,
              <https://www.rfc-editor.org/info/bcp180>.
              At the time of writing, this BCP comprises the following:

              Brzozowski, J., Tremblay, J., Chen, J., and T. Mrugalski,
              "DHCPv6 Redundancy Deployment Considerations", BCP 180,
              RFC 6853, DOI 10.17487/RFC6853, February 2013,
              <https://www.rfc-editor.org/info/rfc6853>.