Frame Reassembly

When reassembly is disabled and a data frame is received, a few scenarios may occur:

If the frame is not a fragment, it is forwarded normally.
If the frame is a fragment and the upper interface is IP (that is, the interface above the Frame Relay subinterface), then the fragment is immediately discarded.

If you enable reassembly, then received fragments undergo the reassembly process. Packets that are not fragments are forwarded as normal.