Hello Lloyd, Wednesday, September 25, 2002, 2:12:13 PM, you wrote: >> >the following distinction : "a datagram is the data unit before >> >fragmentation" ; "a packet is a piece of a fragmented datagram". >> >> :^) >> >> A fragment of a datagram is itself a datagram; after you re-assemble them, >> the result is still a datagram. Yes, I agree, though the definition has - in common habit and use - quite fuzzy contours. In theory, theory would be like pratice; but in practice, pratice isn't theory. ;) > A datagram is self-describing; full source and destination. A fragment > (IPv4 fragment) may not be. Don't be misled by the word fragment: in the IP case, it retains src and dst info as well. No RFC needs to be read to confirm that ;), a little thinking shows that: how could it be routed at layer 3 on an internet, otherwise? In the fragmentation process a datagram/packet may "lose" in its "self contained unit" ULP information, like TCP ports, but that's not matter of IP. .FT