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The LME in each aircraft shall process received broadcast XID_CMD_HO (P=0)
and determine if the ground LME had performed a broadcast link recovery (and
possibly an expedited subnetwork recovery) for it. It shall do this by verifying
that the Ground Station Address Filter parameter contains the DLS address of the
ground station that it is connected to and that a Broadcast Connection parameter
exists containing its aircraft address. Aircraft LMEs supporting broadcast
recovery shall consider that a link handoff has occurred with the new link having
the same parameters as the old link (as modified by the parameters in the
broadcast XID). The old link shall be disconnected immediately.
The Broadcast Connection parameter shall include the subnetwork connection
information (i.e., the M/I and LCI subfields) for only those subnetwork
connections between the aircraft DTE and the peer ground DTEs that the ground
LME maintained. Aircraft LMEs supporting broadcast subnetwork connection
management shall process the remainder of the Broadcast Connection parameter
to determine which subnetwork connections the ground LME maintained. For
those subnetwork connections associated with the logical channels on the old link
that the ground LME maintained, the aircraft DTE shall consider as if the CALL
REQUEST and CALL ACCEPTED sent on the old link were resent on the new
link (except that the M/I bit in the Broadcast Connection parameter shall
supersede the value in the previous CALL ACCEPTED). At this point the
aircraft DTE, ground DCE, and ground DTE shall be initialized. If the Broadcast
Connection parameter indicates that the ground was not able to maintain a
subnetwork connection (i.e., a particular LCI is not mentioned in the Broadcast
Connection parameter), the aircraft shall explicitly establish this subnetwork
connection per Section 188.8.131.52.3.3.1.
If the aircraft LME does not support broadcast recovery, but the ground LME
performed a broadcast link recovery for it, then the aircraft LME shall perform
either an air-initiated link handoff, (if the aircraft LME supports same) or request
a ground-initiated link handoff.
If the aircraft LME finds the new ground station unacceptable, it shall perform an
air-initiated handoff (if the aircraft LME supports same) or request a link
If the Ground Station Address Filter parameter does not equal the DLS address of
a link that the aircraft LME has or if no aircraft identifier subfield in a Broadcast
Connection parameter equals its aircraft address, the aircraft LME shall not
process the ground requested broadcast handoff.
If the aircraft LME supports broadcast link handoffs but does not support
broadcast subnetwork connection management and the Broadcast Connection
field is implemented per Table 3-48, the aircraft shall explicitly establish its
If the Broadcast Connection parameter indicates that a subnetwork connection
was maintained, but the aircraft LME does not recognize that subnetwork
connection, then the aircraft DTE shall transmit a CLEAR REQUEST for each
unrecognized subnetwork connection.
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