in RFC 4750 page 53, there is a parameter called "ospfNbrIpAddr", I am not sure exactly what it means.

Suppose I have two router, they are connected through physical ethernet port1, router A port1: ip, router B port1: ip In this case, ospfNbrIpAddr is, is this right?

Suppose now two routers are connected with GRE tunnel through physical port1. router A port1:, GRE_A:, router B port1:, GRE_B:, now, ospfNbrIpAddr should set to, is this right?

And I have no idea what happened when they connect through unnumbered port? what is "address of another of the neighbor's interfaces"? It can be any?

Thanks for any help, this question is urgent, and please answer with authorized source, thanks.

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1 Answer 1


You may get more/better answers if you clarify your GRE tunnel question.

If you are referring to an OspfNbrEntry for an adjacency over your GRE tunnel, router A would report the value of router B's adjacency on that GRE interface is

In the case of an unnumbered interface, the ospfNbrIpAddr should be absent. Instead, the ospfNbrAddressLessIndex will contain the SNMP ifIndex of the interface. See that entry at the beginning of RFC 4750 page 54, just below the section you referenced earlier.

This Cisco example might also be helpful.

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