The department receives its IPv4 and IPv6 address allocations from the University. For IPv4, the University has a /16 allocation which is not aggregated under the JANET NREN. For IPv6, the University receives its allocation as a /48 site prefix from JANET.

IPv6 network prefix allocation

The department currently has approximately 10 (non-contiguous) /24 IPv4 prefixes allocated to it by the campus computing services department (ISS).

For IPv6, JANET has the prefix 2001:630::/32 from RIPE NCC, as the national academic ISP in the UK. The University has been allocated 2001:630:d0::/48 by JANET. The department has been allocated a /52 size prefix 2001:630:d0::/52.

The department is a RIPE member and could obtain LIR status (as Muenster has done). However, we have not applied for an IPv6 prefix at this time.

In the initial deployment, we expect that IPv4 and IPv6 subnets will be congruent (and thus share and run over the same VLANs). We feel in an initial deployment that this approach simplifies management. We numbered our IPv6 links by topology, depending on which links were attached to which subrouter (in effect, an arbitrary scheme, given our small number of links – 15 or so).

The advantage for IPv6 is that subnets will not need to be resized to conserve or efficiently utilise address space as is the case currently for IPv4 (as subnet host counts rise and fall for administrative or research group growth/decline reasons).

Hard coded IP information:

• The IP prefix allocation from the university

IPv6 Address allocation

It is expected that the network devices will use a combination of address allocation mechanisms:

• Manually configured addresses (in some servers)
• Stateful DHCPv6 (probably in fixed, wired devices and some servers)
• Stateless address autoconfiguration (probably in wireless and mobile devices)
• RFC3041 privacy addresses (in some client devices)

For devices using stateless or RFC3041 mechanisms, a Stateless DHCPv6 server will be required for other (non-address) configuration options, e.g. DNS and NTP servers.

There is some concern over the use of RFC3041 addresses, due to the complexities it causes for tracking devices and knowing which network accesses are actually made by the same node over time.