I am studying for my bsci test and have a lab setup with a simple PTP link between 2 routers. The link is over a serial connection on a pair of 2500 routers. I configured EIGRP on both routers and added the respective LAN networks into eigrp on each. After adding the PTP /30 networks into eigrp on both sides, everything works fine.
My question is that on my companies production network, I have a PTP link between 2 locations (DS3) and do not have the /30 network added to eigrp and routing works fine. Why is this?
Each side is setup with the respective LAN network added to EIGRP, but that's it (other than a re-distributed default route).
What am I missing...?
Assuming that this is the explanation then I would say that the good news is that it is still working - even when logically it should not. The bad news is that if either router reloads (or perhaps if one of the interfaces stops and restarts) then it will not work. I would certainly suggest that the configuration should be changed to have network statements that cover these serial links on both routers.