From the Presidential Advance Manual (stamped "Sensitive - Do Not Copy"):
The first step to keeping demonstrators out of events, the manual tells the president's event staff, is to encourage the Secret Service to "ask the local police department to designate a protest area...preferably not in view of the event site or the motorcade route."Protest areas and "free speech zones" have no place in American society. Their only purpose is to protect the powerful and muzzle dissent.
Also in the document, we learn the true purpose of rally squads.
These squads should be instructed always to look for demonstators. The rally squad's task is to use their signs and banners as shields between the demonstrators and the main press platform. If the demonstrators are yelling, rally squads can begin and lead supportive chants to drown out the protestors (USA! USA! USA!).
As a last resort, security should remove the demonstrators from the event site.
For large rallies... at least one squad should be 'roaming' throughout the perimeter of the event to look for potential problems.