(OSPF) some connected networks not distributed as such

23 May 2002

      Good Day,

This may be a cause of my newfound ignorance on the subject of OSPF
routing, but it has had me boggled for a good part of the last two days. I
have a linux 2.4 machine running bird on a non-broadcast connection to a
Cisco 1600. The linux machine has the following configuration:

----- (interface connected to area 0) ----------------------------------
eth0      Link encap:Ethernet  HWaddr 00:60:97:C2:36:47
          inet addr:213.196.8.130  Bcast:213.196.8.135 Mask:255.255.255.248
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

----- (interface that is the target of exchanged routes) ---------------
eth2      Link encap:Ethernet  HWaddr 00:50:04:02:3B:91
          inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
eth2:0    Link encap:Ethernet  HWaddr 00:50:04:02:3B:91
          inet addr:202.36.147.1  Bcast:202.36.147.255  Mask:255.255.255.0
eth2:1    Link encap:Ethernet  HWaddr 00:50:04:02:3B:91
          inet addr:202.36.148.1  Bcast:202.36.148.255  Mask:255.255.255.0
eth2:2    Link encap:Ethernet  HWaddr 00:50:04:02:3B:91
          inet addr:202.50.64.1  Bcast:202.50.71.255  Mask:255.255.248.0

----- (bird configuration on the machine) ------------------------------
router id 213.196.8.130;
filter outroute_filter {
        if net ~ 213.196.8.136/29 then accept;
        if net ~ 202.36.147.0/24 then accept;
        if net ~ 202.36.148.0/24 then accept;
        if net ~ 202.50.64.0/21 then accept;
        else reject;
};
protocol static {
        preference 1;
        route 202.36.147.0:255.255.255.0 via "eth2";
        route 202.36.148.0:255.255.255.0 via "eth2";
        route 202.50.64.0:255.255.248.0 via "eth2";
}
protocol ospf MyOSPF {
        area 0 {
                tick 1;
                interface "eth1" {
                        type nonbroadcast;
                        stub yes;
                };
                interface "eth0" {
                        hello 30;
                        retransmit 5;
                        cost 10;
                        type nonbroadcast;
                        authentication none;
                        neighbors {
                                213.196.8.133 eligible;
                        };
                        strict nonbroadcast yes;
                };
                interface "eth2" {
                        cost 5;
                        type nonbroadcast;
                };
                interface "eth2:0" {
                        cost 5;
                        type nonbroadcast;
                };
                interface "eth2:1" {
                        cost 5;
                        type nonbroadcast;
                };
                interface "eth2:2" {
                        cost 5;
                        type nonbroadcast;
                };
                interface "*" {
                        stub yes;
                };
        };
        import filter { reject; };
        export filter outroute_filter;
};

-----( cisco configuration )------------------------------------------
interface Ethernet0
 description vlan2
 ip address 213.196.8.133 255.255.255.248
 ip access-group 101 out
 no ip redirects
 ip nat inside
 ip ospf network non-broadcast
!
router ospf 31338
 network 202.36.147.0 0.0.0.255 area 6
 network 202.36.148.0 0.0.0.255 area 6
 network 202.50.64.0 0.0.7.255 area 6
 neighbor 213.196.8.131 priority 1
 neighbor 213.196.8.130 priority 1
!

-----------( the problem )----------------------------------------------
gw-vlan2#sho ip route ospf
O E2 202.36.148.0/24 [110/10000] via 213.196.8.130, 00:00:25, Ethernet0
O    202.36.147.0/24 [110/15] via 213.196.8.130, 00:00:25, Ethernet0
O E2 202.50.64.0/21 [110/10000] via 213.196.8.130, 00:00:25, Ethernet0
gw-vlan2# sho ip ospf database router 213.196.8.130

       OSPF Router with ID (213.196.8.133) (Process ID 31338)

                Router Link States (Area 0)

  Routing Bit Set on this LSA
  LS age: 399
  Options: (No TOS-capability, No DC)
  LS Type: Router Links
  Link State ID: 213.196.8.130
  Advertising Router: 213.196.8.130
  LS Seq Number: 80000002
  Checksum: 0x6342
  Length: 72
  AS Boundary Router
   Number of Links: 2

    Link connected to: a Transit Network
     (Link ID) Designated Router address: 213.196.8.130
     (Link Data) Router Interface address: 213.196.8.130
      Number of TOS metrics: 0
       TOS 0 Metrics: 10
    Link connected to: a Stub Network
     (Link ID) Network/subnet number: 202.36.147.0
     (Link Data) Network Mask: 255.255.255.0
      Number of TOS metrics: 0
       TOS 0 Metrics: 5

So... Which of the two (cisco or bird) made the decision that somehow
202.36.147.0/24 is a connected link whereas 202.36.148.0/24 is an external
route, even though it is connected to the same interface? My head is
hurting :)

Cheers,
Pi

-- 
This could have been your donkey.

Pim van Riezen

Ondrej Filip

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