Here i have this topology in my company
cores configure with VSS, As we can see single link connecting each router to each core which make this link single point of fail, so I need to add link between each router and the other core acting as something like ether channel between two switches to avoid this failure probability from my network , like the next topology
i'm asking about if there is any link aggregation method on the router side (some thing like L3 port aggregation on switches )
NOTE my routers plateform is 2921 and run Version 15.2(4)M6a