Hello Juan
I understand how route poisoning and poison reverse can be a bit confuing, especially because of the similar terminologies. Let me try to clarify.
First of all, you must keep in mind that in the context of RIP, poison reverse is not a process that is used exclusively in conjuction with route poisoning. According to the RIPv2 RFC 2453, RIP uses what is called “split horizon with poison reverse.” As stated in the RFC:
The “simple split horizon” scheme omits routes learned from one neighbor in updates sent to that neighbor. “Split horizon with poisoned reverse” includes such routes in updates, but sets their metrics to infinity.
And…
In general, split horizon with poisoned reverse is safer than simple split horizon. If two routers have routes pointing at each other, advertising reverse routes with a metric of 16 will break the loop immediately. If the reverse routes are simply not advertised, the erroneous routes will have to be eliminated by waiting for a timeout.
So poison reverse makes the process much more efficient.
Keep in mind that poison reverse is a mechanism that happens with any type of update that may be received, and not just with a triggered update, as in the lesson. Does that make sense?
I hope this has been helpful!
Laz