constraint
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The addressing constraints described in this document are largely the
result of the interaction of existing router technology, address
assignment ...
... routers can deal with larger routing and more
dynamic tables, it may be appropriate to review these constraints.
...
... registry is required.
7. Due to constraints on the available free pool of IPv4 address
space, the use of static IP address ...
... later assignment.
5. Due to technical and implementation constraints on the Internet
routing system ...