Hello,
I am experiencing what appears to be an OSPF Area Range (route summarization) issue on RouterOS 7.23.1 running on a CCR1036.
My topology contains a non-backbone OSPF area with Area ID 0.0.0.1, and the router is acting as an ABR.
My objective is to reduce the routing table size by summarizing routes within the 172.25.25.0/24 network using OSPF Area Range.
After creating an Area Range with the prefix 172.25.25.0/24, I expected OSPF to advertise the summarized 172.25.25.0/24 route toward other areas.
Instead, OSPF only advertises 172.25.25.0/30, and the remaining routes contained within the /24 summary disappear from the routing table.
An important detail is that the 172.25.25.0/24 range contains multiple active /30 networks. This is not a case where only a single /30 subnet exists inside the summary range.
When at least one specific /30 subnet within that range is active, OSPF advertises only 172.25.25.0/30 instead of the configured 172.25.25.0/24 summary.
However, when I disable the interface associated with the 172.25.25.0/30 network, the expected summarized route 172.25.25.0/24 immediately appears and is advertised correctly.
This behavior is fully reproducible.
The strange part is that there are still multiple active /30 networks inside the 172.25.25.0/24 range, yet OSPF seems to prefer advertising only the lowest /30 subnet instead of generating the configured summary LSA.
This makes it appear as though OSPF is selecting one of the active subnets within the configured Area Range and generating the summary LSA using that subnet mask rather than the configured summary prefix.
I have already performed the following troubleshooting steps:
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Rebooted the router.
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Disabled and re-enabled OSPF.
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Configured explicit cost values on both the Area and Area Range.
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Verified that the Area Range configuration is correct.
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Confirmed that the behavior is consistently reproducible.
My questions are:
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Is this a known RouterOS v7 OSPF Area Range bug?
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Does RouterOS have any limitation when multiple connected /30 networks exist inside the configured summary range?
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Has anyone observed OSPF generating a summary LSA using the mask of an active subnet instead of the configured Area Range prefix?
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Is there any recommended workaround other than using route filters or advertising a static blackhole summary route?
According to MikroTik documentation, an ABR should originate a single Type-3 Summary LSA for the configured area range whenever routes exist within that range, so the observed behavior appears inconsistent with the documented operation.
Any insight or confirmation from other RouterOS v7 users would be greatly appreciated.
