GR654 - Namur-Reims-Vézelay
From the Via Mosana at Namur a route is marked as the GR654 along the Meuse to the French border, and thence via Reims, Vitry-le-François and Auxerre to Vézelay; there is an FFRP topoguide for this.
Hervé Grosdoit-Artur gives more details on the route in Aube on his site, together with suggestions for links from Troyes and elsewhere in the département.