On 2.8.2013 0:46, Marc, LX1DUC wrote:
The most efficient way is probably the way the RIRs have been handling out allocation in the last couple of years. It's probably just easier to determinate the network size and assign the first available network of that size. Eventually you could temporarily reserve the adjacent network of the same size so that the network could be extended to that size if necessary. An example:
44.a.0.0/27 for user A 44.a.0.32/27 reserved for user A extension or until exhaustion of the 44.a.0.0/16 block 44.a.0.64/27 for user B 44.a.0.92/27 reserved for user B or until exhaustion 44.a.0.128/26 for user C 44.a.0.192/26 reserved for user C etc etc
Once you have filled all of 44.a.0.0/16 you can start allocating the reserved blocks. However if in the meantime user B needs more addresses, you can extend his allocation from 44.a.0.64/27 to 44.a.0.64/26. The renumbering is pretty easy in that case, a change if netmask is all that is required (in this example). OTOH there is no link between a physical LAN and the addressing, a physical LAN might be using 2 or more subnets (44.a.0.64/26 and 44.a.0.192/26) for addressing.
I noticed that in AMPR this is the way IP allocation is handled and I totally support it. I do it the same way in other network.
I think this is the best approach when you are dealing with subnetting and you do not know how usage will expand.
Pedja YT9TP