Technical information
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Least Cost Routing
Least Cost Routing
Least Cost Routing (LCR) provides an economical way of sending faxes to the fax server closest to the ultimate
destination. When a fax is submitted, the system looks in the LCR rules file to find a fax destination that handles
faxes for a specific area code and/or country. If no match is found, the fax is sent locally.
The LCR function consists of two tables: an LCR rules file and an LCR routes file. The LCR rules file contains
information about the routes and the associated country codes and area codes for that route. The LCR routes file
contains the routes and their associated email addresses.
Let's assume you have a fax domain in New York and one in London, and your company sends a lot of faxes from
New York to Paris. Rather than sending the Paris faxes from the New York fax domain, you can create an LCR entry
in the LCR rules file that will route the Paris faxes via the London fax domain. As a result you save on the
transatlantic phone costs.
LCR can be turned on or off using the lcr tag. The lcr tag defaults to true, allowing Least Cost Routing of faxes
based on country and area codes. However, you can turn LCR off by setting the lcr tag to false.
Functional overview
Once a fax is submitted for transmission, VSI-FAX determines what type of request you are sending. If the request is
a simple request, the dial string is converted and subsequently examined by the fax server on which the request is
entered. The server checks the LCR rules file to see if the fax number qualifies for routing.
If the number matches the LCR rules file, the fax server builds a tag file containing information from the local fax
request database to describe the fax request. Items such as recipient name, recipient company, from hostname, and
from sequence number are included in this tag file to ensure the remote server's log is as complete as possible.
The vfxolog shows information for both local and LCR routed faxes transmitted on behalf of another fax server. It
should be noted that, for security reasons, all routed faxes are submitted to a remote fax server with a client ID of
vsilcr.
The initiating fax server emails the fax request to the fax server specified in the LCR routes file. The fax servers poll
the mail account specified in the [VPOPD] section of the $VSIFAX/lib/vsisrv.ini file and look for messages.
When the server receives the email message, it drops it into the autosend directory as a tag file and proceeds to
send the fax out. The LCR system does the following:
1. Generates a response for the fax request.
2. Sends the response back to the originating server.
3. Updates the vfxolog status.
4. Completes the fax request.
Note
When vfxolog output is viewed after the fax is complete, two entries will be added. The first is the original fax
request, and the second is the LCR fax request. The LCR request will have a client ID of vsilcr. User vsilcr
is installed by default and should never be removed.
LCR cluster
An LCR cluster is two or more LCR-enabled fax servers configured to route faxes among one another in order to
minimize telephone charges.