OSPF stuck in 2-way state

[Ondrej Zajicek]

On Thu, Oct 03, 2019 at 01:49:23PM +0000, Kenth Eriksson wrote:
> Hi!
> 
> We are having a problem were sometimes bird ospf neighbor state machine
> becomes stuck in a 2-way state. This happens when two broadcast
> interfaces are connected, one of them is running quagga and the other
> end is running bird. The quagga router has prio 0 and bird prio 5, i.e.
> quagga is not eligible to become DR.
> 
> Why does not bird transition from 2-way to ExStart? 
> 
> I believe the following lines causes me.dr to become 0.0.0.0. Bird adds
> itself as an eligible router as described in section 10.4, but with the
> address of zero? 
> 
>   me.dr  = ospf_is_v2(p) ? ipa_to_u32(ifa->drip) : ifa->drid;
>   me.bdr = ospf_is_v2(p) ? ipa_to_u32(ifa->bdrip) : ifa->bdrid;

Hi

I do not get why do you think that it is added with the address of zero.
There is a line above specifying local address is used:

  me.ip = ifa->addr->ip;


It seems to me that quagga elected bird, but bird for some reason does
not elect itself.


How often does it happen in that configuration? The election should be
relatively deterministic, it should happen just on order of wait timers
expiration and hello packet reception.

-- 
Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at crfreenet.org)
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"To err is human -- to blame it on a computer is even more so."