OSPF neighbor in PTMP network not removed on reloading configuration

[Ruben Laban]

Hi Cyrill,

I ran into something similar quite some time ago. Back then the 
conclusion pretty much was: use firewalling to kill the already 
established session.

Regards,
Ruben

On 2014-02-12 20:20, Cyrill Gössi wrote:
> 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?
>
> Im sure I miss the obvious here.
>
> I will be glad about any help in this matter!
>
> Thanks in advance.
>
> Best, Cyrill