About address allocating

[Francis Dupont]

 In your previous mail you wrote:

   hi, I have the following questions about address allocating:
     I know SLA is /48, and interface ID should be 64 bits, 
   does it mean that the smallest unit when allocating address is /48?
   In other words, if I allocate a /48 to a large university, could I 
   allocate a /48 to four middle schools, thus each middle school gets
   an block less than /48, which is /50. Is this plan reasonable?

=> we'd like to get a /48, ISPs would like to give a /64 to us:
 - /48 seems a bit too large for a default allocation size
 - /64 is unusable when you need subneting
then the current idea, as presented yesterday here in Budapest
at the RIPE meeting, is to introduce "small site" which get
/56 (on byte boundary, large enough for up to 256 subnetworks or
a few levels of hierarchy).
Then /56 will become the default allocation size in RIR
allocation & assignment document.

Regards

Francis.Dupont@enst-bretagne.fr