The value of tmnxMcPathChlSrcBwFallDelay specifies the value the
bandwidth manager uses the falling-delay threshold to hold on to the
previous highest bandwidth until the delay time has expired while
operating in dynamic bandwidth mode. This allows the bandwidth manager
ignore momentary drops in channel bandwidth. This value can only be set
if tmnxMcPathChlSrcBwActivity is not set to 'none'.
The default value of '0' means that there is no source override and
tmnxMcPathBdlChlBwFallDelay should be used.