Multiple class C assignment ensures effective assignment and utilization of the address space. As a single class B address has ability to assign 2^16 hosts, there are very few, if any, organization which will require this much address space. Giving multiple class C addresses to an organization seems the logical choice as each class C block has 256 hosts.

Disadvantages of this approach are big routing/forwarding tables as instead of one class B entry, several class C entries will be made in the routers for packet routing. Big routing tables mean longer processing time at the routers.

IPv6 handles greater then 64 KB payload by using the Jumbo Payload option which increases the payload length to 2^64 = 4 GB.