Hi
I’m new to mikrotik consider that 
I’m looking for a way to setup my Rb751 router in a way that makes it able to detect, if one of my 2 ISPs are failed and switch to the other line im provided it with
i mean somthing like making a Routemap in sisco devices using IP SLA
can anyone give me an explication
Dual-WAN setups are the most common question I answer on the forums, nearly once or twice a day.
Short of using the search feature on the forums to locate the information you need, set the “distance” on the default routes such that your preferred provider has the lowest number and enable the “check gateway” option by “ping”. When either gateway is not reachable via ping, it will disable the route, removing it from active selection. At any given time, the lowest distance active default route will be selected (assuming a more specific route is not also defined).