Hello,

I'm trying to redistribute routes from another routing daemon through 
synchronization of the kernel table using the kernel protocol in BIRD 2.0.4. 
However, I run into some problems that not all routes are imported by the BIRD 
router.

The kernel routing table contains the following routing table:
# ip route
10.0.0.0/24 dev eth0 proto kernel scope link src 10.0.0.1
10.0.1.3 via 10.0.1.4 dev eth1 proto zebra metric 2
10.0.1.4 dev eth1 proto zebra scope link metric 1
10.0.4.0/24 via 10.0.0.2 dev eth0 proto bird metric 32

The interface eth1 has the address 10.0.1.1/32 in an ad-hoc routing domain, 
through OSPF-MDR (which is an extension of Quagga) it finds the direct neighbor 
10.0.1.4 which is added as "10.0.1.4 dev eth1 proto zebra scope link metric 1". 
The neighbor 10.0.1.4 advertises that it can forward to 10.0.1.3 which is added 
as "10.0.1.3 via 10.0.1.4 dev eth1 proto zebra metric 2". The routing of 
OSPF-MDR works, in the sense that 10.0.1.1 can reach 10.0.1.3 and 10.0.1.4.

However, when we try to import these routes from the protocol kernel into the 
Bird routing table, only the directly connected route to 10.0.1.4 shows while 
the route to 10.0.1.3 are not imported:
# birdc show route
BIRD 2.0.4 ready.
Table master4:
10.0.1.4/32          unicast [kernel1 10:27:29.329] (10)
                dev eth1
10.0.4.0/24          unicast [babel1 10:27:23.461 from fe80::200:ff:feaa:4] 
(130/96) [00:00:00:00:0a:00:00:02]
                via 10.0.0.2 on eth0
10.0.0.0/24          unicast [direct1 10:27:21.870] * (240)
                dev eth0
                     unicast [babel1 10:27:23.461 from fe80::200:ff:feaa:4] 
(130/96) [00:00:00:00:0a:00:00:02]
                via 10.0.0.2 on eth0

Additionally, the bird.log file throws the following error:
2019-05-15 10:27:21.869 <INFO> Started
2019-05-15 10:27:21.902 <WARN> Missing broadcast address for interface vxlan0
2019-05-15 10:27:29.329 <ERR> KRT: Received route 10.0.1.3/32 with strange 
next-hop 10.0.1.4

It may be that kernel protocol rejects the route because the next-hop is not in 
the interface its regular netmask (which is set to /32), though I am not 
familiar enough with the source code to determine the exact cause except that 
the error gets thrown from sysdep/linux/netlink.c line 1643. However, I think 
the line should be accepted since there is another routing rule confirming that 
the next-hop is directly attached to device eth1. Given the explicit error I 
don't think this is a configuration error (though I am open to learn more), so 
I hope BIRD can be patched to solve this.

I have attached the bird.conf file, as well as an image of the example 
topology. Above snippets and config file are taken from node n1 which is 
running both the OSPF-MDR router based on Quagga and BIRD Router.

Any help would be much appreciated.

Thanks in advance,
Niels van Adrichem

[cid:[email protected]]

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Attachment: bird.conf
Description: bird.conf

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