If you’ve read my previous posts on FAST Search in SharePoint 2010, you’ll be familiar with my article where I describe the issues I had with the Content Distributor ports for FAST.
My initial research into this issue let me to the following blog: http://fastforum.info/viewtopic.php?f=6&t=223.
Basically the users commenting in this thread talk about an inconsistency between the Install_Info.txt file and the ContentDistributor.cfg file in terms of the port number which is set to 13390. It was always odd to me that the Install_Info.txt and ContentDistributor.cfg file were not consistent and many believe this to be incorrect.
The change that you would make would be an update to the FAST Search Connector in Central Admin, so that the port number reflects what’s in the ContentDistributor.cfg file. While this may work temporarily, this is INCORRECT!
The port for the Content Distributor should be AS IS reflected in the Install_Info.txt file. So 13391 if you stuck with the defaults.
Read the following from a KB article from MS:
The “Fast Connector SSA” may be incorrectly configured to use port 13390. The %FASTSEARCH%install_info.txt” displays the Content Distributors with port “13391”, however the %FASTSEARCH%etccontentdistributor.cfg” displays port 13390. If the portfor the “Content Distributors” in the “Fast Connector SSA” was configured as “13390”, connectivity to FAST will fail. If this is the case, the “Content Distributors” in the “Fast Connector SSA” should be reconfigured to use port 13391 as stated in the install_info.txt.