OSPF neighbor in PTMP network not removed on reloading configuration

12 Feb 2014

      Hy BIRD community.

I have a fairly simple setup of 3 routers connected in a "triangle-shape"
through an ethernet network. The routers have IPs 15.0.0.1, 15.0.0.2 and
15.0.0.3. The essential part of the configuration files look as follows:

// Router 15.0.0.1
protocol ospf {
    table baseTable;
    area 0.0.0.0 {
        interface "eth1" {
            type pointomultipoint;
            strict nonbroadcast yes;
            neighbors {
                15.0.0.2;
            };
        };
    };
}

// Router 15.0.0.2
protocol ospf {
    table baseTable;
    area 0.0.0.0 {
        interface "eth2" {
            type pointomultipoint;
            strict nonbroadcast yes;
            neighbors {
                15.0.0.1;
                15.0.0.3
            };
        };
    };
}

// Router 15.0.0.3
protocol ospf {
    table baseTable;
    area 0.0.0.0 {
        interface "eth3" {
            type pointomultipoint;
            strict nonbroadcast yes;
            neighbors {
                15.0.0.2;
            };
        };
    };
}

If I start the routers like this and sniff the traffic on "eth3" is see
router 15.0.0.2 sending Hello-packets to both other routers. Routers
15.0.0.1 and 15.0.0.3 send their Hello-packets only to 15.0.0.2.

So far so good!

If I add the neighbor 15.0.0.1 to router 15.0.0.3 and also add neighbor
15.0.0.3 to router 15.0.0.1 and issue a "configure" to reload the
configuration I see that all routers now issue 2 Hello packets - one for
each of their neighbors listed in the neighbors {} section.

Still - so far so good!

However, if I now undo the last step (adding the neighbors to router
15.0.0.1 and 15.0.0.3) and issue the "configure" command again to let BIRD
adopt to the new setting, all routers still keep on issuing exactly as
before 2 Hello packets - one for each of their former neighbors.

Why is that? How could I make BIRD aware that the neighbor-relationship has
to be undone after having removed the neighbors from the list again?

I'm sure I miss the obvious here.

I will be glad about any help in this matter!

Thanks in advance.

Best, Cyrill

OSPF neighbor in PTMP network not removed on reloading configuration

Cyrill Gössi