ibgp bird 1.6 vs 2.0

[Matěj Grégr]

Hello,
  we have encountered a different ibgp behavior between bird 1.6 and
bird2, and I am not sure if it's an intentional change in bird2 or a
bug. Let's consider the following topology:

      192.168.1.0/24           192.168.2.0/24
 R1 ------- ebgp ------- R2 ------- ibgp ------- R3
   .2                 .1   .1                  .2

R1 uses AS 65001, R2 and R3 uses AS 65000. R1 propagates some routes
(e.g. 10.10.10.0/24) via eBGP to R2, which sends them to R3 via iBGP.
bird2 config on R3:

template bgp IBGP {
        local as 65000;
        direct;
        ipv4 {
                next hop self;
                import keep filtered on;
                import all;
        };
}

protocol bgp from IBGP { neighbor 192.168.2.1 as 65000; }

Now there are two issues:

1) the bird on R3 reports "Invalid NEXT_HOP attribute" and doesn't learn
any R1 routes from R2. If the "direct" option is removed from the
config, R3 will learn R1 routes. However, if R3 runs bird1.6, it learns
all routes even with the direct option.
According to the docs, "direct" is a check for directly connected
neighbors. The neighbor 192.168.2.1 is directly connected and in the
same subnet, so I don't understand, why there is an issue with NEXT_HOP
and why are routes silently dropped on R3?

2) If direct is removed from the config, bird2 on R3 learns R1 routes,
but with status unreachable. Even if I send 192.168.1.0/24 from R2 to R3
so the route 192.168.1.0/24 is in R3's routing table and ping from R3 to
the NEXT_HOP IP address is successful. bird1.6 works without a problem
with or without direct option and all routes are learned and reachable.
According to the docs, iBGP should find route to NEXT_HOP IP address in
its routing table, so why are the routes marked as unreachable in bird2,
if the route is there?

Thank you and best regards,
M.

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