Re: OSPFv2: PtP stub interface

7 Jul 2026

      Good morning Lexi,

I believe the issue might be this one:

	define OSPF_V4_EXPORT = [
		0.0.0.0/0
	];

0.0.0.0/0 matches only the default route *exactly*, nothing shorter.
What you probably meant is:

0.0.0.0/0+ (default route and everything shorter as well).

Best regards,

Nico

<#secure method=pgpmime mode=sign>
Lexi Winter <lexi@le-fay.org> writes:
...
hello,
i'm using BIRD 3.2.0 on FreeBSD 15.0.  i have a PPPoE interface with a
point-to-point IPv4 address configured:
ng0: flags=10088d1<UP,POINTOPOINT,RUNNING,NOARP,SIMPLEX,MULTICAST,LOWER_UP> metric 0 mtu 1500
      options=0
      inet 81.187.73.117 --> 81.187.81.187/32
      inet6 2001:8b0:aab5:1::1/128
      inet6 fe80::227c:14ff:fef3:d8f7%ng0/64 scopeid 0x12
      groups: arpa
      nd6 options=1<PERFORMNUD>
i would like to advertise this in OSPF as a passive interface, so i configured
the OSPF protocol:
define OSPF_V6_EXPORT = [
  ];
define OSPF_V4_EXPORT = [
      0.0.0.0/0
  ];
filter ospf_export {
      if (net ~ OSPF_V6_EXPORT) then accept;
      if (net ~ OSPF_V4_EXPORT) then accept;
      reject;
  };
protocol ospf v2 core4 {
      ipv4 {
      	export filter ospf_export;
      	import all;
      };
area 0 {
      	interface "ng0" {
      		stub yes;
      	};
      	[... other config elided ...]
      };
  }
however, BIRD does not advertise 81.187.73.117/32 in OSPF.  it *does* advertise
81.187.81.187/32, which is the remote side of the interface.
the interface looks fine in BIRD:
bird> show ospf interface "ng0"
  core6:
core4:
  Interface ng0 (peer 81.187.81.187)
      Type: ptp
      Area: 0.0.0.0 (0)
      State: PtP (stub)
      Priority: 1
      Cost: 10
      ECMP weight: 1
      Hello timer: 10
      Wait timer: 40
      Dead timer: 40
      Retransmit timer: 5
the route:
bird> show route for 81.187.73.117/32
  Table master4:
  0.0.0.0/0            unicast [kernel4 2026-07-04] ! (10)
      via 81.187.81.187 on ng0
  81.187.73.117/32     unicast [kernel4 2026-07-04] ! (10)
      dev lo0
if i add 81.187.73.117/32 to OSPF_V4_EXPORT, then it is correctly advertised as
an E2 route, which is fine as a workaround, but i would like to understand why
the interface configuration doesn't work.
--
Sustainable and modern Infrastructures by ungleich.ch

Re: OSPFv2: PtP stub interface

Nico Schottelius