I think this kind of topic may be a course basic, but I'm still have a lot of technical doubts on how to implement redundant links on Layer 3, for example:
-In order to use dual homing for a remote site, for example:
|Router 1|-----(link 1, ISP 1, etc.)-----|Router 2| |________|-----(link2, ISP2, etc.)-------|________|
- Is it always necessary to use different ISPs?
- Regarding the protocol configuration, the new link should be in the same area (in OSPF) or as the same level (in IS-IS) or participate in any way on the existing process?
- Should create a whole new process on the router for this specific link?
- This will not cause a L3 loop? -Would this be avoided (L3 loop) by simply giving a higher cost to one of the links?