The WebMux MAP (Multiple Address and Port) feature allows you to set up a farm with a single set of servers that have multiple services that are dependent on each other to be considered alive. For example, you have an HTTP service on port 80 and an FTP service on port 21. You can set up a farm with MAP enabled and have the Farm IP listening on both port 80 and port 21. This configuration would look something like this:
In a MAP farm, the health checking of the servers are a combination of the services you set up for the farm. In this case, the servers are being checked for HTTP on port 80 and FTP on port 21. If any one of those services fail on a server, that server would be considered dead and taken out of service from the farm. For example, if the FTP service on port 21 dies, but HTTP service on port 80 is still working, the WebMux will consider the whole server to be out of service. This is helpful in cases where the availability of all the services on the server is a requirement for the server to be considered functional. This may not always be the desired operation.
In some cases where there are multiple services running on a single server, but each service is not dependent on each other to be considered functional, setting up separate farms for each service and using the same set of servers will allow for a more granular health checking. For example:
In this case, IP address of 192.168.12.100 acts as a single access point for port 80 and 21, much like a MAP farm. However, the main difference now is that the WebMux considers the HTTP and FTP health checking independent from each other. So, if the FTP service on 192.168.11.11 dies, but the HTTP service is still running, the server will only be taken out of service in the FTP farm. The HTTP farm will still consider that server alive and continue to send traffic to port 80.
The MAP feature can also be used to add additional farm IP addresses to a cluster of servers. For example:
This example shows two IP address on different networks serving HTTP service on port 80. This may be useful in cases where there might be two Internet gateways or the WebMux is serving on different VLANs.