HNA and IPv6

As HNA messages are made up of network addresses and netmasks, it would seem natural to replace the netmask used in IPv4 HNA messages (figure 4.2) with the network prefix length when using IPv6. As displayed in figure 7.2, this would only require 8 bits compared to the 128 bits required to construct an IPv6 netmask. At first this was the way IPv6 HNA messages was implemented in olsrd, but after some discussion on the MANET mailing-list, it was decided to use the netmask approach for IPv6 as well to keep RFC compliance.

Figure: A IPv6 HNA packet containing one network announcement containing a netmask compared to one containing the prefix length. This prefix approach could also be used on IPv4 HNA messages.