In the following figure, exactly one protocol dataunit (pdu) in layer n is encapsulated in a pduat
layer (n – 1). it is also possible to breakone n-level pdu into multiple (n – 1)-levelpdus
(fragmentation) or to group multiple n-level pdusinto one (n – 1)-level pdu (packing).
a. for fragmentation, is it necessary that each (n– 1)-level segment contain a copy of thenlevel
header?
b. for packing, is it necessary that each n-levelpdu retain its own header, or can the data be
consolidated into a single n-level pdu with asingle n-level header?