I have a hub and spoke network, spokes connected with ovpn to hub and rip configured. Each spoke has 3 connected networks that are advertised to the hub. The problem is that there are hundreds of spokes and there's some flapping going on - either spokes that get disconnected or interfaces that go down, mostly natural causes

Is there a way to summarize routes at each spoke? The spokes each advertise a /26, /27 and /28.
The RIP timers are set at 15s/30s/45s. Would it help if I set them higher, let's say at minutes ?
Any other way of mitigating the route flapping ? Static routing is not an option and if possible I would like to avoid ospf
