Is it possible to configure an aggregation etherchannel between two routers and one L3 switch, means that : the one link in : R1 <-> L3 Switch1 , and the second aggregation link in : R2 <-> L3 Switch1 ? in this topology, the target is that one IP adress will be flapping and shared by the two both separate router aggregate to one L3 switch with one portchannel IP ? if yes, could anyone advise how to do that ?
No. All the channel members on one end of the channel must be on the same device. If you are looking for a single IP address in the switch, you could do that on an SVI and connect layer-2 switch interfaces to the routers, but you do not want duplicate addresses, and you cannot channel to two separate devices.