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Prioritized operators and retransmissions explained

This FAQ answers two questions

  • When you define active WinPager periods and operator groups, you have to choose between the three priority groups: "Primary", "Backup" and "Reference". What's the difference between the three groups ?
  • I've noticed that the delivery of some alarm messages fails. How many times will WinPager try to retransmit the alarm message ?

Answer

Operator priorities

When defining a weekly period, a special period or a group of operators, each operator can be assigned to one of three priority groups: "Primary", "Backup" and "Reference". Read the following to understand the differences between the groups:

Primary operators:

Primary operators are the primary recipients of alarm messages and WinPager will try to deliver any message to all the primary operators.

Backup operators:

These operators serve as backup for the primary operators. Only when none of the primary operators could be reached, WinPager will deliver the message to the backup operators. WinPager will try to reach the backup operators one at a time in the exact order in which they are placed in the backup group. Only if the first backup operator cannot be reached, the next backup operator (if any) will be used, and so on.

Reference operators:

These operators serve only as carbon copy recipients. All alarm messages will be sent to all reference operators. Should the delivery to any or all of the reference operators fail, no further action will be taken by WinPager.

Retransmission of messages

Whenever WinPager attempts to send a message to an operator, there is a risk that the paging service used will fail to deliver the message. By default, WinPager will attempt to deliver any message to an operator up to three times. If the message has not been delivered after three attempts, the delivery of the message will be marked as failed.

The number of delivery attempts is configurable for each paging service and is therefore neither related to the operator nor the priority group in which the operator has been placed.

Examples

The following are four example scenarios showing how WinPager handles various degrees of failed deliveries. All examples use the same operator configuration,i.e. they use several operators in each priority group (WinPager only requires a single operator in the primary group).

To the right of each operator is shown the result of each attempt to deliver the message.

Example 1 - 'Normal' situation where everything works correctly

Primary:

  P1   Success

  P2   Success

Backup:

  B1   (not used)

  B2   (not used)

  B3   (not used)

Reference:

  R1   Success

  R2   Success

The message is delivered successfully to all the primary and reference operators by the first attempt. The backup operators are therefore not used.

Example 2 - All delivery attempts to reference operators fail, backup operators not used

Primary:

  P1   Success

  P2   Success

Backup:

  B1   (not used)

  B2   (not used)

  B3   (not used)

Reference:

  R1   Fail   Fail   Fail

  R2   Fail   Fail   Fail

The message is delivered successfully to the primary operators by the first attempt, but all delivery attempts to the reference operators fail. Since the primary operators have received the message the backup operators are not used.

Example 3 - One primary operator fails all attempts

Primary:

  P1   Fail   Fail   Fail

  P2   Success

Backup:

  B1   (not used)

  B2   (not used)

  B3   (not used)

Reference:

  R1   Fail   Fail   Fail

  R2   Fail   Fail   Fail

Almost like example 2 but all delivery attempts to the first primary operator fail. Since the message was delivered to the second primary operator no backup operators are used though.

Example 4 - Delivery attempts to primary operators fail and backup operators are used

Primary:

  P1   Fail   Fail   Fail

  P2   Fail   Fail   Fail

Backup:

  B1  Fail   Fail   Fail

  B2  Success

  B3  (not used)

Reference:

  R1   Success

  R2   Success

All primary operators fail and therefore the first backup operator is used. The first backup operator also fails resulting in the use of the second backup operator which eventually receives the message.

If we assume that only one modem is used in example 4 then the attempts to send the message to the operators will happen in the order shown below:

a) P1, Attempt 1 - Fails!

b) P2, Attempt 1 - Fails!

c) R1, Attempt 1 - Succeeds!

d) R2, Attempt 1 - Succeeds!

e) P1, Attempt 2 - Fails!

f) P2, Attempt 2 - Fails!

g) P1, Attempt 3 - Fails!

h) P2, Attempt 3 - Fails!

    (All primary operators have now reached the max. number of

     attempts - the backup operators enter the scene!)

i) B1, Attempt 1 - Fails!

j) B1, Attempt 2 - Fails!

k) B1, Attempt 3 - Fails!

    (Activate the next backup)

l) B2, Attempt 1 - Succeeds!

m) B3, Not used since B2 succeded.

Note that these four scenarios only illustrate the handling of a single alarm message. If WinPager had fetched several alarm messages from IGSS then the dialout process of all the messages would appear very complex. But nevertheless if extracting the events for any single alarm from the event log the processing of that alarm would resemble these four scenarios.