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Unformatted text preview: ENDED STANDARD FOR COMMUNICATIONS OPERATION PROCEDURE-1 The ‘Alert’ notifications relating to the transmission count may occur as a result of a break in the underlying Physical Layer and may therefore be caused by problems outside the Data Link Layer. All other ‘Alert’ notifications report the breakdown of the Data Link Layer protocol. This means that some part of the system is not operating to specification (therefore, reports already received by the procedures above FOP-1 are likely to have been incorrect). In particular, an ‘Alert’ notification shall be issued by FOP-1 of the Virtual Channel in which the error condition was detected; but, given that the protocol mechanism has broken down, it is possible that the Virtual Channel Identifier in the received data is incorrect. Therefore, a single failure may cause the same or different ‘Alert’ notifications on more than one Virtual Channel. In general, once an ‘Alert’ occurs, no further ‘Alert’ can occur until after the FOP-1 receives one of the Directives to initiate the AD Service. The exception to this is the ‘Alert’ LLIF, which can occur at any time. 4.3.3 SUSPEND By setting Timeout_Type to ‘1’ and setting a small value of T1_Initial, it is possible to cause FOP-1 to transmit a sequence of Type-AD Transfer Frames a specified number of times and then suspend its operation, without clearing its buffers. The ‘Suspend’ notification shall be used to notify that the transmissions have been completed and that the operation has been suspended. A subsequent ‘Resume’ Directive shall then cause FOP-1 to resume operation in the same state it was in when it was suspended. 4.4 4.4.1 TRANSFER NOTIFICATION GENERAL The protocol entity shall notify the user at the sending end of an event associated with the transfer of a service data unit by passing the service indication primitive in the form of XXX_Notify.indication, where XXX is a service name (see reference [3]). The type of notification shall be indicated by the parameter Notification Type of the XXX_Notify.indica...
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This document was uploaded on 03/06/2014.

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