John Potts died from a head injury after a fracas with Gordon Robson outside NE38 Sports Bar in Barmston, Washington, in November 2014.
Robson, 26, of Waskerley Road, Barmston, admitted manslaughter at an earlier court hearing.
The judge said Mr Potts, of Sunderland, had been acting as peacemaker when he received a single blow.
A man has been jailed for three-and-a-half years after admitting killing another man outside a bar on Wearside.