How to do OSPF with pt(m)p over a /31 tunnel?

RouterOS Forwarding Protocols
1

How can I properly add neighbors for ptp and ptmp?

There is only an “NBMA Neighbors” tab and “Neighbors” is readonly.

Also, what is the proper way to configure OSPF over a point-to-point link (IPIP or GRE) with a /31 network? Say the tunnel endpoint has 192.168.1.254/31 and the Mikrotik has 192.168.1.255/31. What would I enter in “Networks”? In my opinion, “192.168.1.255/31” would be proper but then I get “Error in Network - network address expected”. I also tried 192.168.1.254/31, and both 192.168.1.254 and 192.168.1.255 at the same time.

Any help appreciated!

2

The simple solutions (if possible) are

  1. don’t use /31 it has issues in mikrotik, just use /32 which you can use the same addressing anyway, or you can totally save on it and use just 1 IP address on the hub router for all neighbours
  2. use point to point type, ptmp also has issues. Simply create 1 VLAN per neighbour. As long as you don’t have MTU issues it’s going to work much better
3

Thanks. I finally got it working with ptp.
In the end, even with the /31.

EDIT: Just for future reference: Check the other tunnel endpoint!
Linux (and derived systems) have the inconvenient property of setting the tunnel ttl to “inherit”. OSPF sets TTL=1 (since they should just go one hop). With ttl=inherit, the encapsulated packet will also have TTL=1 and be discarded by the first router.