There has recently been a change to the IPv6 address allocations used in the University, though at present this affects relatively few people. The reason for the change is that the original allocation to Cambridge was not thought to be large enough; a larger allocation was subsequently obtained but this entails phasing out the old addresses.
The use of
2001:630:200::/48 is now deprecated in Cambridge, and these addresses might one day be allocated to a different institution. The replacement allocation is
2001:630:210::/44. The address space in use in the Computer Lab is now
2001:630:212:200:/56. There is no guarantee that the address space used in CL will always be contiguous, but the 256 subnets we have been allocated should last us for some time.
This change should only affect people who are doing any kind of address filtering or access list that uses numeric addresses.