At 04:32 PM 9/23/2002 -0700, Michel Py wrote:
I thought a datagram was at the same layer than a packet, the difference
being what they contain: A packet contains data issued from a
connection-oriented protocol (such as TCP) from the layer above, when a
datagram contains data issued from a connectionless protocol (such as
Packet-switching refers to data chunks that contain destination
addresses. It might contain other information, such as source address, but
this is not required.) They can be relayed in a fixed fashion essentially
making a connection) or dynamically routed.
The term packet-switching is generic, even used by some to describe what is
done for email relaying. (Others are not so happy with that particular usage.)
There is no strict, formal, official distinction between packet or
datagram. The tendency is to use packet for referring to the lower-levels,
and datagram at the higher. But how high or how low?
For example, IP is a packet-switching protocol, yet its units are called
datagrams. UDP uses the term datagram.
Dave Crocker <mailto:dave(_at_)tribalwise(_dot_)com>
TribalWise, Inc. <http://www.tribalwise.com>
tel +1.408.246.8253; fax +1.408.850.1850