It was also observed that three out of the 10 home router implementations demonstrated support for DHCPv6 prefix delegation allowing the router to further break up a large delegation of prefixes to a home network.
In addition to the required testing, some observations were made around 6RD, DS-Lite and DHCPv6 servers supporting prefix delegation on the LAN interfaces. There was a significant increase in the support for transition mechanisms in comparison to previous test events. Half of the implementations supported DS-Lite and 6RD. These features were added at the request of ISPs deploying IPv6.
Issues that were observed during the test affecting IPv6 home router implementations -- many of which were resolved post-event in order to satisfy the World IPv6 Launch requirements --included:
* DHCP Solicits Frequency. In early deployments of DHCPv6, some servers may be configured to assign addresses, but not delegated prefixes. If the DHCPv6 server is not delegating prefixes, home routers will continue to transmit DHCPv6 Solicits. DHCPv6 exponentially backs off its message retransmission until reaching a Maximum Retransmission Time for Solicits (SOL_MAX_RT), which is 120 seconds. Thus, the frequencies of Solicit messages in this scenario have been noted to cause too much unwanted traffic in ISP networks.
A requirement was recently added to IETF 6204bis to support a new DHCPv6 option that can update the default value of SOL_MAX_RT to 3600 seconds. ISPs can utilize this new option to lessen the aggregated traffic toward their DHCPv6 infrastructure. During the test event it was observed that about a third of the participating home routers supported the ability to increase the value of SOL_MAX_RT through some mechanism. One implementation demonstrated the ability to process a properly formatted SOL_MAX_RT option as described in the draft, which allows the variable to be set. Since the option-code had not been officially assigned, a temporary option-code was selected to demonstrate support for the new option at the event. The option was successfully processed by the client, which adjusted its max solicit timer to the value sent by the server. It is critical for home routers to support this option in order to avoid becoming a detriment to ongoing IPv6 deployment efforts.