as SP, Grafik Packet and ESKAY, some of which make use of the KISS mode
feature of the TNC.
To use the DAMA system, the user connects to the DAMA master with a normal
connect frame. When the master responds to the connect frame, the TNC is auto
-
matically placed into DAMA slave mode. The DAMA master polls each slave
within the LAN in a “round-robin” fashion (somewhat like the token passing
method) and the slave TNCs transmit packets when the master has granted per
-
mission to do so. The slave TNCs continue to be polled with priority among the
slaves assigned according to the number of times each responds with information
frames (as opposed to rr frames - i.e., no data to send). Priority is dynamically
assigned so that those stations that are sending information are polled more fre
-
quently than idle stations. However, once an “idle” station responds with infor-
mation, its priority is upgraded.
Communication over the wider area is handled between the DAMA master nodes
which are connected to each other using a standard NET/ROM
™ type protocol.
For the DAMA system to work effectively, each slave associates with only one
master node and connects only to that master. If an end user is connected to
more than one master, each master will poll the slave TNC according to its poll-
ing schedule. When polled, the slave TNC will transmit all frames it has avail-
able to whichever master polls it. This would increase the probability of
collisions with other users, thus defeating the purpose of the DAMA system.
How is DAMA Implemented in Kantronics TNCs?
Most Kantronics TNCs, including the KPC-3 Plus, KPC-9612 Plus, and the
KAM Plus, implement the DAMA slave mode, using the following commands
(see the Command Reference section for details):
DAMA {ON|OFF}
Set DAMA to ON to have your Kantronics TNC operate as a DAMA slave sta
-
tion once a connection is established with a DAMA master station. When
DAMA is OFF, the TNC will operate in it’s carrier sense multiple access mode
(CSMA). For details, see the CD, SLOT, and PERSIST commands in the Com
-
mand Reference section of this manual.
Packet Modes of Operation Other Modes of Operation
User’s Guide 216 KAM’98 v 8.3
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