I have dug some more and tried to change network interface setting

on 10.30.1.0/31 RFC 3021  link (no broadcast), doesn't propagate route
on 10.30.1.1/30 link, doesn't propagate routes
on 10.30.1.1/29 link, propagates routes just fine

Similar setup "just works" in FRR so I'm now very confused on what is
happening.

Setup is 3 devices (other router and core L3 switches) all with
separate VLAN and /31 assigned to it.

Regards

Mariusz


On Wed, 11 Feb 2026 16:57:09 +0100
Mariusz Gronczewski <[email protected]> wrote:

> Hi,
> 
> I'm trying to replace one of our Junipers and I've come up with
> bizzare problem.
> 
> I'm trying to run OSPF instance on VRF (I don't think problem is VRF
> related, I tried without VRF and it's same result) and I see both
> peers and the LSA database are getting filled
> 
> ☠ ip r sh vrf vrf-core
> 10.30.0.0/31 dev b-swcore.3011 proto kernel scope link src 10.30.0.0 
> 10.30.0.4/31 dev b-swcore.3012 proto kernel scope link src 10.30.0.4 
> 10.30.1.0/31 dev b-swcore.3000 proto kernel scope link src 10.30.1.0 
> 
> bird> show  ospf neighbors   
> core:
> Router ID     Pri          State      DTime
> Interface  Router IP 10.100.1.1         1     Full/PtP
> 37.905        b-swcore.3011 10.30.0.1 10.100.1.2        1
> Full/PtP      37.904  b-swcore.3012 10.30.0.5
> 193.200.227.2 128     Full/PtP        39.907
> b-swcore.3000 10.30.1.1
> 
> bird> show ospf state   
> 
> area 0.0.0.0
> 
>       router 193.200.227.1
>               distance 0
>               router 10.100.1.1 metric 10
>               router 10.100.1.2 metric 10
>               router 193.200.227.2 metric 10
>               stubnet 193.200.227.1/32 metric 0
>               stubnet 10.30.1.0/31 metric 10
>               stubnet 10.30.0.0/31 metric 10
>               stubnet 10.30.0.4/31 metric 10
>               stubnet 10.30.1.0/31 metric 10
> bird> show ospf topology   
> 
> area 0.0.0.0
> 
>       router 193.200.227.1
>               distance 0
>               router 10.100.1.1 metric 10
>               router 10.100.1.2 metric 10
>               router 193.200.227.2 metric 10
> 
> bird> show protocols   
> Name       Proto      Table      State  Since         Info
> device1    Device     ---        up     2026-02-11 15:43:43.320  
> kcore      Kernel     master4    up     2026-02-11 15:43:43.320  
> core       OSPF       master4    up     2026-02-11 15:43:43.320
> Running
> 
> (kcore is fetching from VRF kernel table to the main bird table)
> 
> config is very bare bones
> 
> protocol ospf core {
>   vrf "vrf-core";
>   ipv4 {
>     import keep filtered on;
>     import all;
>     export all;
> 
>   };
>   area 0 {
>     interface "b-swcore.30*" {
> 
>     };
>     interface "vrf-core" {
>       stub;
>     };
> 
>   };
> 
> };
> 
> protocol kernel kcore {
>   kernel table 1002;
>   learn all;
>   ipv4 {
>     export none; 
>     import all;
> 
> };
> 
> };
> 
> but I'm only getting my own routes
> 
> bird> show route   
> Table master4:
> 10.30.1.0/31         unicast [core 2026-02-11 16:21:37.684] * I
> (150/10) [193.200.227.1] dev b-swcore.3000
>                      unicast [kcore 2026-02-11 16:21:38.584] (10)
>       dev b-swcore.3000
> 10.30.0.0/31         unicast [core 2026-02-11 16:21:37.684] * I
> (150/10) [193.200.227.1] dev b-swcore.3011
>                      unicast [kcore 2026-02-11 16:21:38.584] (10)
>       dev b-swcore.3011
> 10.30.0.4/31         unicast [core 2026-02-11 16:21:37.684] * I
> (150/10) [193.200.227.1] dev b-swcore.3012
>                      unicast [kcore 2026-02-11 16:21:38.584] (10)
>       dev b-swcore.3012
> 193.200.227.1/32     unicast [core 2026-02-11 16:21:37.684] * I
> (150/0) [193.200.227.1] dev vrf-core
> bird>   
> 
> 
> 
> 
> So far I tried running it outside of VRF and adding some PtP related
> options to OSPF but it didn't change anything I'm getting warnings
> about broadcast address
> 
> Feb 11 16:21:37 d1-r1 bird[7194]: Missing broadcast address for
> interface b-swcore.3011 Feb 11 16:21:37 d1-r1 bird[7194]: Missing
> broadcast address for interface b-swcore.3012 Feb 11 16:21:37 d1-r1
> bird[7194]: Missing broadcast address for interface b-swcore.3000
> 
> but those appear to be unrelated, I've changed one of the /31 links to
> /30 and nothing changed
> 
> Version is 3.1.0 from Debian package but I also tried to downgrade to
> 2.x with no effect.
> 
> The P2P links are just vlans to juniper and our 2 core switches
> 
> on other side I also get no routes
> 
> xani@r2> show ospf database advertising-router 193.200.227.1      
> 
>     OSPF database, Area 0.0.0.0
>  Type       ID               Adv Rtr           Seq      Age  Opt
> Cksum  Len Router   193.200.227.1    193.200.227.1    0x80000060
> 347  0x42 0xadd4 108
> 
> while at same time getting some
> 
> bird> show ospf lsadb router 193.200.227.1  
> 
> Area 0.0.0.0
> 
>  Type   LS ID           Router          Sequence   Age  Checksum
>  0001  193.200.227.1   193.200.227.1    80000076    76    cd17
> bird> show ospf lsadb router 193.200.227.2  
> 
> Global
> 
>  Type   LS ID           Router          Sequence   Age  Checksum
>  0005  88.156.75.236   193.200.227.2    8000c3e1  1249    3340
>  0005  193.200.227.2   193.200.227.2    8002a08f  2150    7d23
>  0005  194.50.132.0    193.200.227.2    80006374  1849    a24f
>  0005  194.50.134.0    193.200.227.2    80006374   648    8c63
>  0005  194.50.135.0    193.200.227.2    80006373  1549    836c
>  0005  212.91.10.200   193.200.227.2    800019e7   948    1b27
>  0005  0.0.0.0         193.200.227.2    80001b60    48    9334
>  0005  46.28.244.72    193.200.227.2    80018367   349    339f
> 
> Area 0.0.0.0
> 
>  Type   LS ID           Router          Sequence   Age  Checksum
>  0001  193.200.227.2   193.200.227.2    8002a1f5    87    074e
>  0002  10.30.1.1       193.200.227.2    80000001    87    427e
> 
> 
> I did try to run very simple equivalent OSPF config on FRR and it
> "just worked" so needless to say I'm very confused by the issue. Any
> ideas how I can even debug what's happening in the first place ?
> 
> Regards



-- 
Mariusz Gronczewski (XANi) <[email protected]>
GnuPG: 0xEA8ACE64
https://devrandom.eu

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