Technical information

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Retry Strategies
Retry Strategies
Retry strategies are an important tool for managing the fax load on your server. A retry strategy defines the number of
times the fax server will try to re-send a fax and how long it will wait between each retry before the fax request is
permanently removed from the active fax queue.
When you send a fax, the retry strategy used for that fax request is either the default retry strategy or another
predefined retry strategy you explicitly assign to that fax request when you create the fax request or via your user
profile.
Basic retry strategies
VSI-FAX provides several basic retry strategies that are optimized for common fax scenarios (e.g., local faxing,
international faxing, etc.). You can also define custom retry strategies to meet your particular needs. This is
accomplished by manually editing the $VSIFAX/lib/retrys.lst file.
The default retrys.lst file, installed with your VSI-FAX server, defines the following basic retry strategies:
default:5,5,5,5
three-attempts:5,5
four-attempts:5,5,5
international:5,5,10,10,60,60,120
The first retry strategy (default), is used whenever no retry strategy is explicitly specified. This retry strategy
defines four retries, five minutes apart.
The three-attempts retry strategy defines two retries, five minutes apart. Notice that although this retry strategy
is named three-attempts that it contains only two entries. This is because these two retries, combined with the
initial send, constitutes three total attempts.
The four-attempts retry strategy is nearly identical to the three-attempts strategy except that an additional retry
is added for a total of four send attempts (i.e., the initial send and three retries) five minutes apart.
The international retry strategy is much more complex because successfully sending an international fax is
much more susceptible to failure. Notice that it defines seven total retries and that the intervals between the
retries gradually increase.
• The assumption is that if the fax cannot be sent within the first 15 minutes (initial send and two retries,
five minutes apart) that there may be a problem with the international phone lines.
• The next two retries are ten minutes apart. If the fax server gets this far into the international retry
strategy a total of 35 minutes has elapsed (15 minutes for the initial send and first two retries and 20
minutes for the third and fourth retries). At this point, it makes sense to let even more time elapse
before the fax server retries this fax.
• The next two retries are an hour (60 minutes) apart. The final retry is two hours from the previous
retry. At this point, the fax server has tried to send the fax a total of eight times in four hours and 35
minutes.
Custom retry strategies
If you find that the basic retry strategies do not meet all your needs, you can easily define new retry strategies by
manually editing the $VSIFAX/lib/retrys.lst file.
Each retry strategy is defined on a separate line. The format of a retry strategy entry is: