Is defense counsel required to provide an estimate of potential guideline sentence when advising defendant on pleading guilty?

QUESTION PRESENTED Is defense counsel required, in order to provide effective assistance of counsel, to give the defendant an estimate of the potential guideline sentence he is facing in advising the defendant on whether to enter a plea of guilty to Federal criminal charges? _ Is defense counsel ineffective when counsel fails and refuses to give a defendant any estimate of the various potential guideline sentences : depending on whether he pleads guilty or goes to trial? / 2