OSPF bug with IPs containing 255

RouterOS Forwarding Protocols
1

Setup:
6 CCRs connected over an ISP-provided L2 WAN link.
Interfaces facing the WAN link assigned a 10.255.255.x/24 IP
OSPF Router ID = WAN IP (I’m using OSPF only for this link so no need for a bridge/loopback).
OSPF Area 0

I just spent 3 days tackling weird OSPF behaviour (some neighbors not appearing, neighbors appearing and receiving LSAs but routes not being loaded, etc). Everything else was fine. Pings, manually adding routes, all good there. Using static NBMA Neigbors helped a little bit, but it was still misbehaving.

After trying everything I tried changing the IP addresses and the Router ID from 10.255.255.x/24 to 10.250.250.x/24, and everything started worked immediately.
I know that, in this subnet, 255 is not considered a broadcast, but I’m suspecting a bug within MikroTik’s OSPF engine is throwing a fit if it sees 255 in the Router ID or in the LSAs.

Did anyone else experience this?

2

The key here is “connected over an ISP-provided L2 WAN link.”

3

Indeed, and I have also escalated this with the ISP, but if it was an ISP issue, why would some of the CCRs work while others don’t? (They’re all on the same ISP).
Also, why would some CCRs see the OSPF neighbors, receive the LSAs, but don’t install the routes? If the ISP was blocking traffic with that IP, there would be no neighbors.

4

Were you previously using that subnet for anything else on those devices? Perhaps subdivided in a different way (ex. with /29’s inside or something like that?)

5

any update?