Attack of amine on amide
There reaction environment would have to be acidic to protonate the amide, the amide is not natively electrophilic enough to be attacked by the amine. 

A possible point of concern is 'won't the nuclophilic amine be protonated?'  And the answer is absolutely.  But the protonation is a reversible reaction, and at equilbrium with a catalytic amount of acid (almost always TSA is used in catalytic quantities), the proton will be exchanged with various, some of which will lead to the condensation resulting in product.