The Hello packets of OSPF will travel between neighbors, for that reason, this packet won't travel from R1 to R2 to R3, only is from R1 and R2 (neighbor relantionship) and R2 and R3 (another neighbor relationship)
For that reason, the Reflexive ACL won't inspect the hello packets of OSPF (because ACL doesn't affect to packet generated by the same router)
I've seen a reference to "per protocol" in addition to your comment. Like:
"Only 1 ACL per interface per direction per protocol.'
I'm NOT questioning your reply because it's excellent. I just wonder:
- Does the "per protocol" condition still apply? And if so.
- What protocol(s)? IP, TCP, UDP? Until now I've assumed it is referring to IPv4 vs IPv6. ??
Thank you. And please hang around. I'm new and I will have more questions.