Streaming to the backup url is optional, though we highly recommend that you use it. The backup url gives you the ability to fallback to another entry point into the network in case the primary entry point (FMS url) is obstructed for some reason. There are many reasons this could occur, but the backup url is a quick and easy option to get your stream going again.
If you stream to both the primary and backup entry points, you will need to have the bandwidth capable for you will be sending double the amount of data from your campus. You can turn on this option in the ‘Options -> Edit’ section of your live stream.