AEA PK-232 Technical Reference Manual page 63

PK-232 TECHNICAL MANUAL
The DXE sending a SABM command will ignore and discard any frames except SABM, DISC, UA,
and DM frames from the other DXE.
Frames other than UA and DM in response to a received SABM will be sent only after the link is set
up and if no outstanding SABM exists.
A.4.3.2 Information-Transfer Phase
After establishing a link connection, the DXE will enter the information-transfer state. In this state,
the DXE will accept and transmit I and S frames according to the procedure outlined in A.4.4, be-
low.
When receiving a SABM command while in the information- transfer state, the DXE will follow the
resetting procedure outlined in
A.4.3.3 Link Disconnection
A.4.3.3.1
While in the information-transfer state, either DXE may indicate a request to disconnect the link by
transmitting a DISC command frame and starting timer T1 (see A.4.7).
A.4.3.3.2
A DXE, upon receiving a valid DISC command, shall send a UA response frame and enter the dis-
connected state. A DXE, upon receiving a UA or DM response to a sent DISC command, shall can-
cel timer T1, and enter the disconnected state.
A.4.3.3.3
If a UA or DM response is not correctly received before T1 times out, the DISC frame should be
sent again and T1 restarted. If this happens N2 times, the DXE should enter the disconnected
state.
A.4.3.4 Disconnected State
A.4.3.4.1
A DXE in the disconnected state shall monitor received commands and react upon the reception of
a SABM as described in
mand.
A.4.3.4.2
In the disconnected state, a DXE may initiate a link set-up as outlined in connection establishment
above (A.4.3.1). It may also respond to the reception of a SABM and establish a connection, or it
may ignore the SABM and send a DM instead.
A.4.3.4.3
Any DXE receiving a command frame other than a SABM or UI frame with the P bit set to one
should respond with a DM frame with the F bit set to one. The offending frame should be ignored.
PK232TM Rev. A 5/87
A.4.6 below.
A.4.3.1 above and will transmit a DM frame in response to a DISC com-
APPENDIX A – AX.25 LEVEL 2 PROTOCOL
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