Subnet ID Deprecation for IPv6

Deprecation of the subnet ID in IPv6 networking is proposed; the subnet ID is set to zero so that all nodes in a site carry the same prefix. While the procedures for neighbor discovery and duplicate address detection have to be changed, possible simplification gains in IPv6 networking including that of intra-site host- and subnet- mobility might be worth the modification. Site-external behaviors don't change through this modification, enabling incremental deployment of the proposal. Sites of manageable sizes for which scalability is not much a critical issue might consider the mode of operation proposed in this document.