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interprime
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OSPFv3 - Area Range

Sun Apr 30, 2017 12:13 am

There has been some modification in ospfv3 for route summarization, I tried to do as in the procedure below but I can not send the advertise summary lsa into the backbone area.
Has anyone ever experienced this?

Here a link with procedure for ospf!
https://wiki.mikrotik.com/wiki/OSPF_and_Area_summaries
 
idlemind
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Re: OSPFv3 - Area Range

Mon May 01, 2017 7:18 am

There has been some modification in ospfv3 for route summarization, I tried to do as in the procedure below but I can not send the advertise summary lsa into the backbone area.
Has anyone ever experienced this?

Here a link with procedure for ospf!
https://wiki.mikrotik.com/wiki/OSPF_and_Area_summaries
The short answer: It won't work the way you're trying to do it. Not broken.

I see you've posted your question a few times lately with roughly the same details. From what you've posted you are using static routes and trying to redistribute those into OSPF. In OSPFv3 those are treated as an AS-external-LSA and are flooded out all router interfaces. This causes the ::/64 prefixes to be added to each router connected to that router and any downstream of that unless they are separated by an excepting type of area. The exceptions include stubby areas, nssa areas and virtual-links (which I think Router OS doesn't support anyways yet).

The routing ospf-v3 area range tells a router acting as an ABR to send an inter-area-prefix LSA into the neighboring area with the summary route you defined. Sadly this never gets generated because it all the areas are being flooded with an intra-area-lsa so OSPF prefers this over summarizing. At least to my understanding.

The AS-external-LSA is limited to including a single prefix, each static route therefore generates it's own LSA.

Here are some relevant readings in the RFCs:

https://tools.ietf.org/html/rfc5340#section-4.4.3.6
https://tools.ietf.org/html/rfc5340#section-4.5.2
https://tools.ietf.org/html/rfc5340#appendix-A.4.7
 
airbanduk
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Re: OSPFv3 - Area Range

Fri Jun 16, 2017 12:12 pm

I am struggling with OSPFv3 areas also, I just can't seem to get the summary to advertise to the backbone.
/ipv6 add print
G 2a07:6a80:c40f::1/48           LOOPBACK-PPPoE

/routing ospf-v3
area print
0  * backbone            0.0.0.0         default
1    area12              0.0.0.12        default

area range print
0   area12                2a07:6a80:c400::/44         calculated yes

interface print
3  P LOOPBACK-PPPoE          area12         10        1 default
If I add the Loopback to the backbone area, I see the 2a07:6a80:c40f::/48 route on other OSPF routers, but from area12, with or without the area range, nothing seems to get advertised to the backbone. Running 6.35 code.
 
airbanduk
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Re: OSPFv3 - Area Range

Fri Jun 16, 2017 1:40 pm

OK, some more testing and I think I know what the problem is. It seems the summary LSAs only get generated by the ABR if there is another OSPF neighbour in that area. This is kind of a problem, because if I want to make each backbone router an ABR to use the summarisation feature, I can only do it on nodes with area neighbours. This isn't the behaviour seen for IPv4 and OSPFv2, where any router can be an ABR regardless of the presence of non-backbone neighbours.

Can anyone confirm this and does anyone know of a workaround better than adding a loopback with an IP address for the required summary to the backbone area?
 
cpiazza
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Re: OSPFv3 - Area Range

Mon Jul 03, 2017 8:32 pm

I can confirm the behaviour, but i dont know if this is a bug or the implementation that mikrotik decided to do.

It would be nice to know if this is the expected behaviour of ospf-v3 in mikrotik or not, because other vendors dont do it this way.

maybe we are missing some config parameter?
 
idlemind
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Re: OSPFv3 - Area Range

Mon Jul 03, 2017 10:31 pm

So just to make sure we are talking about the same thing:

The original post author was trying to redistribute static's and that was generating AS-External-LSA's.

You're noting that an OSPFv3 process doesn't advertise an area range into another area unless the area generating the summary has at least 1 active neighbor. I can confirm this behavior in 6.40rc24. It also doesn't seem to be restricted by the OSPFv3 RFC so I'm going to go out on a limb and say this is a bug. Especially since OSPFv2 supports this behavior.

Speculation: The inter-area prefix LSA is only being generated when network LSAs are being calculated? You can see them in GNS3 immediately after a neighborship is formed. LS Updates go out into the other areas from the ASBR and naturally the summary shows up.

MikroTik forum ops, can we get a nod on this or do we need to send this to support@mikrotik.com?

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