Routing

This is only a lab, but I was working on some OSPF and I noticed that one of the OSPF routes was not appearing in 'show ospf database'. It does appear in 'show route' and 'show ospf database detail/extensive'.

The network in question is 192.168.10.0/24, advertised by RID 2.2.2.2.

show route:

2.2.2.2/32         *[OSPF/10] 00:13:13, metric 2
                    > to 10.10.2.2 via ge-0/0/0.0
10.10.2.0/30       *[Direct/0] 00:42:46
                    > via ge-0/0/0.0
10.10.2.1/32       *[Local/0] 00:43:05
                      Local via ge-0/0/0.0
192.168.10.1/32    *[OSPF/10] 00:13:13, metric 2
                    > to 10.10.2.2 via ge-0/0/0.0

show ospf database:

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Router   2.2.2.2          2.2.2.2          0x8000000c   768  0x22 0x76d3  60
Network *10.10.2.1        1.1.1.1          0x80000004   773  0x22 0xd43e  32

show ospf database extensive:

Router   2.2.2.2          2.2.2.2          0x8000000c   456  0x22 0x76d3  60
  bits 0x0, link count 3
  id 192.168.10.1, data 255.255.255.255, Type Stub (3)
    Topology count: 0, Default metric: 1
  id 10.10.2.1, data 10.10.2.2, Type Transit (2)
    Topology count: 0, Default metric: 1
  id 2.2.2.2, data 255.255.255.255, Type Stub (3)
    Topology count: 0, Default metric: 1
  Topology default (ID 0)
    Type: Transit, Node ID: 10.10.2.1
      Metric: 1, Bidirectional
  Aging timer 00:52:23
  Installed 00:07:35 ago, expires in 00:52:24, sent 00:07:35 ago
  Last changed 00:07:35 ago, Change count: 7

Hello,

Your 192.168.10.0/24 route is not appearing anywhere in Your printouts below.

192.168.10.1 255.255.255.255 (192.168.10.1/32) is appearing instead.

Is 192.168.10.1 a loopback address? Or PPP/HDLC link endpoint address?

Please post the complete configs.

HTH

Thanks
Alex

I completely overlooked that. I was using a loopback interface, but I thought I put a /24 IP on the interface.

When I get back to my lab this evening I will double-check. I wonder if it's translating the /24 to a /32 since its a loopback interface, or if I misconfigured it.

Interesting.

I verified that the advertising router has both the interface and the OSPF network statement configured for a /24 network. Yet the route is showing up on the Juniper as a /32, but regardless of the network size, it's not showing up in the OSPF database.

On the advertising (Cisco):

interface Loopback1
 ip address 192.168.10.1 255.255.255.0
end

DC-RTR#sh run | b router ospf
router ospf 1
 router-id 2.2.2.2
 log-adjacency-changes
 passive-interface Loopback0
 passive-interface Loopback1
 network 2.2.2.2 0.0.0.0 area 0     ##Loop 0
 network 10.10.2.0 0.0.0.3 area 0     ##Physical L3
 network 192.168.10.0 0.0.0.255 area 0     ##Loop1

But what's weird is that it isn't showing up in the Cisco router's OSPF database either.

Hi there,

You need this command in CSCO router to allow loopback to be advertised in OSPF as /24

interface Loopback1
ip ospf network point-to-point

See this explanation https://learningnetwork.cisco.com/thread/37960#200740  

HTH

Thanks

Alex

Thanks, the route now appears correctly in the routing table as a /24 network.

But could somebody explain to me why the network only appears in the OSPF database when I show extensive?

root> show ospf database

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Router  *1.1.1.1          1.1.1.1          0x80000005   188  0x22 0xe5d2  48
Router   2.2.2.2          2.2.2.2          0x80000004    73  0x22 0x7cd6  60
Router   3.3.3.3          3.3.3.3          0x80000003   192  0x22 0x7355  48
Network *10.10.2.1        1.1.1.1          0x80000001   197  0x22 0xda3b  32
Network *10.10.3.1        1.1.1.1          0x80000001   191  0x22 0x20f   32
    OSPF AS SCOPE link state database
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Extern   192.168.50.0     3.3.3.3          0x80000001   256  0x20 0xb345  36

root> show ospf database extensive

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Router   2.2.2.2          2.2.2.2          0x80000004    83  0x22 0x7cd6  60
  bits 0x0, link count 3
  id 192.168.10.0, data 255.255.255.0, Type Stub (3)
    Topology count: 0, Default metric: 1
  id 10.10.2.1, data 10.10.2.2, Type Transit (2)
    Topology count: 0, Default metric: 1
  id 2.2.2.2, data 255.255.255.255, Type Stub (3)
    Topology count: 0, Default metric: 1
  Topology default (ID 0)
    Type: Transit, Node ID: 10.10.2.1
      Metric: 1, Bidirectional
  Aging timer 00:58:36
  Installed 00:01:22 ago, expires in 00:58:37, sent 00:01:20 ago
  Last changed 00:01:22 ago, Change count: 3

Hello,

---

@robert.juric wrote:

Thanks, the route now appears correctly in the routing table as a /24 network.

 

But could somebody explain to me why the network only appears in the OSPF database when I show extensive?

 

---

"show ospf database" displays the list of LSAs + few select fields of each LSA.

The subnet You are talking about is contained inside "router LSA" a.k.a. Type-1 LSA.

"show ospf database extensive" displays all fields of all LSAs.

For more information about "router LSA" see RFC 2328 section 12.4.1

http://www.ietf.org/rfc/rfc2328.txt

HTH

Thanks

Alex

Thank you sir!