Two link backup,,,help me please

Dears,

Happy new year

i have rb1100 and i have two link from the same isp one link primary and other is backup

i need to put the primary link in eth1 and backup in eth2

please help me to make the primary link work and ping to the gateway but if the geteway get request time out the rb1100 switch to the backup link

Kindly help me.


Note that i didn,t need the boiding way.