I've just watched the incident again on the clip that CAM posted (provided by Norwich).

Interestingly the Norwich commentator initially seemed to think their player may have been in trouble as a result of the challenge that saw McDonald sent off.

The referee immediately produced the red card for McDonald.

A number of Norwich players then approached McDonald in an aggressive manner and several Rotherham players stepped in to protect their team-mate.

The whole thing was just a minor scuffle with no real harm done. A written warning to both clubs about their future conduct should be the maximum sanction. Anything else would be a total overreaction.