Hi Jose,
The problem is that we can only “attach” the default route to a route-map. We need something to match in the route-map so that’s why I picked a dummy prefix. We put this dummy route in the routing table and attach object tracking to it.
We then attach IP SLA to object tracking.
When IP SLA fails, the object tracking fails and the dummy prefix is removed from the routing table.
This triggers the route-map and the default route is no longer advertised anymore…
In this example, R2 is only advertising a default route. That doesn’t mean automatically that it knows a default route itself. If you want to use R3 for all unknown traffic then yes, you should add a default route towards R3. In this example I only explained how to advertise a default route in combination with IP SLA.
Rene