SATO WS408DT Technical Manual page 106

7 Network Network Architecture
IP is the commonly used protocol in the network layer. It defines an address
system and provides end-to-end communication for data transmission. The packet
is delivered based on the IP address in the IP header, which is attached to the
packet. However, the packet may be lost, corrupted or out-of-order when it travels
across the network, because IP doesn't ensure the delivery. TCP can prevent most
of these things happen.
The data link is on the data link layer. Its task is to create and manage a reliable
data transmission between two adjacent nodes in a network via MAC addresses. It
divides the data from the network layer into bits, encodes these bits into frames
prior to transmission, and decodes them at the destination. The data link also
provides the error control and flow control. The error control uses a frame check
sequence (FCS) to ensure that the delivered frames are intact and the flow control
ensures that the fast sender doesn't overwhelm the slow receiver with data.
This architecture allows up to five computers to connect to a printer via the same
port. When you turn on your printer, it opens the maximum number of ports and
is waiting for a session request. Once your printer receives a request, it establishes
a session and set it as "connected." If all of the sessions are occupied, no more
connection is allowed. In this case, your printer returns the RST signal to the
computer that made a request via the TCP protocol. When your printer finishes its
communication with the computer, it releases the session to get ready for a new
connection.
Data processing is determined by the connection priority. When your printer
connects to multiple computers, it only processes the data from the oldest session
(the first connected computer). The connection priority changes when there is a
disconnection. Other computer needs to wait until its session becomes the oldest.
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