Rajon RondoThe rising cacophony of Rajon Rondo trade rumors is just that: Noise, and nothing more.

Speculation on Monday that the Houston Rockets are interested in trading for Rondo has “no substance,” multiple sources told the Boston Herald. The Celtics have engaged in no trade-related communication with the Rockets, according to the report.

Celtics president of basketball operations Danny Ainge “has been pretty firm in the past on his need to get a major player in return for his All-Star point guard,” Steve Bulpett of the Herald wrote Tuesday. “And while (Ainge) has to realize Rondo’s impending 2015 free agency may change the game a bit, he is still under no time pressure to pull the trigger.”

Standing firm on demands and refusing to trade Rondo altogether are two separate things, obviously. Now that LeBron James, Carmelo Anthony and other big names are off the market in free agency, attention will shift to free-agents-to-be like Rondo and Kevin Love. The Rondo rumor mill is only getting started.

As it pertains to the Rockets, though, there isn’t a whole lot there. Houston is flush with financial flexibility, but it has very little in the way of attractive trade assets. To make matters worse for Houston, the Dallas Mavericks reportedly rejected the Rockets’ request to turn Chandler Parsons’ free-agent signing into a sign-and-trade, which would have netted Houston a valuable trade exception.

Short of making James Harden or Dwight Howard available — and perhaps not even then — there is not much the Rockets can do to entice Boston into trading Rondo.