4. Description of the RPCM Device
The test based on ICMP echo requests/replies (pings). If the ICMP packets reach the device under
test, and the test passes within specified timing parameters, the device is considered available.
Monitoring
— has two values "
NO
" or "
YES
", the field is intended to indicate the watch-
dog status;
Current alarm value, loss %
— percentage of currently observed lost packets used com-
pare against alarm limit value;
Alarm limit, loss %
— the maximum number of lost packets to trigger an alert;
Alarm limit, s
— stabilization delay before alarm is triggered;
Alarm
— indicated whether alarm is currently active;
Last alarm time
— information about the date and time when the last alarm was trig-
gered;
Current restart value, loss %
— percentage of currently observed lost packets used
compare against restart limit value;
Restart limit, loss %
— the maximum number of lost packets to trigger a restart;
Restart limit, s
— stabilization delay before triggering restart;
Restart in progress
— indicates whether the restart process has been triggered;
Auto restart initiated at:
— the date and time the device restart procedure was initiated;
Last check time
— time of last control.
Note. The method of calculating the observed loss values for alarms and restarts used in ICMP echo request/reply (ping)
tests.
ICMP echo requests are sent every Check interval, s.
If after sending ICMP echo request, the reply does not arrive within the Request timeout, s, the packet is considered lost.
Results of ICMP echo requests/replies (pings) for alarm and restart purposes are collected in their own queues. Sizes of
queues are calculated according to the following formulas: Qa = Da / I and Qr = Dr / I, where:
Qa – size of Alarm packet loss queue
Qr – size of Restart packet loss queue
Da – “Min. duration for alarm, s” value
Dr – “Min. duration for restart, s” value
I - “Check interval, s” value
Each ICMP echo request/reply (ping) result value swaps the oldest value to ensure that the queue does not overflow.
Loss percentage is calculated according to the following formulas: Pa = La / Qa x 100 and Pr = Lr / Qr x 100, where:
Pa - “Current alarm value, loss %” value
Pr - “Current restart value, loss %” value
La – number of packets in Alarm packet loss queue, that have exceeded “Max. latency limit, ms” or “Request timeout, s”
values
Lr – number of packets in
Restart
packet loss queue, that have exceeded “Max. latency limit, ms” or “Request timeout, s”
values
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