The case studies above discuss the general scenarios and deployment procedures that were followed in each case. In each case, the challenges in deployment were generally technical but understood, rather than ‘exploratory’. Thus very few, if any, unexpected results or difficulties were encountered. Quite the opposite – the deployments described have gone very well and have been very positive.

Here we repeat a small summary of the unforeseen issues captured in the scenarios above:

• A surprising level of fear, uncertainty and doubt (FUD) about the IPv6 technology by certain administrators that we had to interact with.
• The fact that if you want to run a tunnel broker service to your staff or students, a /48 prefix is not big enough for a campus unless the broker users only get a /64 prefix, which is not ideal.
• Lack of VLAN capability where it was desired, preventing the VLAN method being used where desired in all cases.
• Variable performance in software driven VLAN tagging; Southampton’s BSD routers hit a forwarding limit with the specific DLINK cards used.
• A desire by network administrators (managers) to use DHCPv6 even when IPv6 supports stateless autoconfiguration. Sites seem used to managing their IP address assets.
• A desire to disable IPv6 Privacy Addresses to make management and monitoring simpler (device identification simpler).
• Unexpected impact on IPv4 security when IPv6 is turned on. This happened in the Lancaster case, but is resolved via a firmware upgrade
• The relative high performance of DSTM versus NAT-PT.
bull; Various issues with totd at Tromso – interactions with certain DNS implementations, with use of IP literals, and systems with AAAA records that do not offer all services over IPv6 transport.
• Some hardware problems to run IPv6 in old PCs, caused by lack of required multicast support in old Ethernet cards. These can be replaced cheaply.
• Abuse of some transitioning relay services. The spammers will find you.

Although these have been overcome, they may represent generic issues that may resurface in similar situations.

For a discussion of issues and challenges remaining for IPv6 deployment, see [D2.5.3].