OSPF. Route from NSSA area does't installs but exists in the DB.

[MaximBudyonny]

Hello,

The issue. Routing table on the R1 have no information about static routes from R3.

But info about links exists in the database on the R1.

Scheme:

[R3]----172.30.30.12/30---[R2]---172.17.17.8/30---[R1]----core network

R3 (RID 10.255.255.4), R2 (RID 10.255.255.9) are int the NSSA area 111.

R3 is ASBR. It must redistribute some static networks to the core.

R1 (RID 10.255.255.13) - ABR, belongs to area 0.

OSPF configs.

======R1======

router ospf 200
router-id 10.255.255.4
log-adjacency-changes
area 0 authentication message-digest
area 111 authentication message-digest
area 111 nssa no-summary
area 1002 authentication message-digest
area 1002 nssa default-information-originate
redistribute static subnets route-map OSPF_STATIC_NET_FILTER
passive-interface default
no passive-interface FastEthernet0/1
no passive-interface Tunnel2
no passive-interface Tunnel300
network 10.255.255.4 0.0.0.0 area 0
network 172.16.17.0 0.0.0.7 area 0
network 172.17.17.8 0.0.0.3 area 111
network 172.22.0.120 0.0.0.3 area 1002
network 172.22.100.36 0.0.0.3 area 0
neighbor 172.22.100.37
neighbor 172.16.17.4
neighbor 172.17.17.10
neighbor 172.22.0.122

======R2======

router ospf 200
router-id 10.255.255.9
log-adjacency-changes
area 111 authentication message-digest
area 111 nssa
passive-interface default
no passive-interface Vlan10
no passive-interface Tunnel2
network 10.255.255.9 0.0.0.0 area 111
network 172.17.17.8 0.0.0.3 area 111
network 172.30.30.12 0.0.0.3 area 111
neighbor 172.30.30.13
neighbor 172.17.17.9

======R3======

router ospf 200
router-id 10.255.255.13
log-adjacency-changes
area 111 authentication message-digest
area 111 nssa
redistribute static subnets route-map OSPF_STATIC_NET_FILTER
passive-interface default
no passive-interface FastEthernet0/0
network 10.255.255.13 0.0.0.0 area 111
network 172.30.30.12 0.0.0.3 area 111
neighbor 172.30.30.14

route-map OSPF_STATIC_NET_FILTER permit 10
match tag 333

ip route 10.10.10.10 255.255.255.255 10.119.76.1 180 tag 333 name XXXX

=============================================================

sample output from the R1.

R1#show ip ospf database nssa-external adv-router 10.255.255.13

GS24-CORE-2#show ip ospf database nssa-external adv-router 10.255.255.13

            OSPF Router with ID (10.255.255.4) (Process ID 200)

                Type-7 AS External Link States (Area 111)

  LS age: 789
  Options: (No TOS-capability, Type 7/5 translation, DC)
  LS Type: AS External Link
  Link State ID: 10.10.10.10 (External Network Number )
  Advertising Router: 10.255.255.13
  LS Seq Number: 80000007
  Checksum: 0x7675
  Length: 36
  Network Mask: /32
        Metric Type: 2 (Larger than any link state path)
        TOS: 0
        Metric: 20
        Forward Address: 10.255.255.13
        External Route Tag: 333

R1#sh ip ro 10.10.10.10
% Subnet not in table

=============================================================

sample output from the R2

R2#sh ip ro 10.10.10.10
Routing entry for 10.10.10.10/32
  Known via "ospf 200", distance 110, metric 20
  Tag 333, type NSSA extern 2, forward metric 51
  Last update from 172.30.30.13 on Vlan10, 02:41:15 ago
  Routing Descriptor Blocks:
  * 172.30.30.13, from 10.255.255.13, 02:41:15 ago, via Vlan10
      Route metric is 20, traffic share count is 1
      Route tag 333
.

R2#show ip ospf database nssa-external adv-router 10.255.255.13

            OSPF Router with ID (10.255.255.9) (Process ID 200)

                Type-7 AS External Link States (Area 111)

  Routing Bit Set on this LSA
  LS age: 961
  Options: (No TOS-capability, Type 7/5 translation, DC)
  LS Type: AS External Link
  Link State ID: 10.10.10.10 (External Network Number )
  Advertising Router: 10.255.255.13
  LS Seq Number: 80000007
  Checksum: 0x7675
  Length: 36
  Network Mask: /32
        Metric Type: 2 (Larger than any link state path)
        TOS: 0
        Metric: 20
        Forward Address: 10.255.255.13
        External Route Tag: 333

[Shahzad Qadir]

Hi,

Can you check if forwarding addres (10.255.255.13) for these redistributed routes is in your routing table? If router don't have this in the routing table it will not install the routes.

If you don't have this route in the routing table then what you can do is configure forward-address-suppression on your ABR that way forward address will become 0.0.0.0 and router will install route in the routing table.

HTH

Shahzad

[MaximBudyonny]

Thank you for reply.

Route to 10.255.255.13 exists.

R1config)#do sh ip ro 10.255.255.13

YARVAL-BACKUP#sh ip ro 10.255.255.6

Routing entry for 10.255.255.13/32

  Known via "static", distance 1, metric 0

  Tag 333

  Redistributing via ospf 200

  Advertised by ospf 200 subnets route-map OSPF_STATIC_NET_FILTER

  Routing Descriptor Blocks:

  * 172.17.17.10

      Route metric is 0, traffic share count is 1

      Route tag 333

R1#sh ip ospf database router 10.255.255.13

            OSPF Router with ID (10.255.255.4) (Process ID 200)

                Router Link States (Area 111)

  Routing Bit Set on this LSA

  LS age: 883

  Options: (No TOS-capability, DC)

  LS Type: Router Links

  Link State ID: 10.255.255.13

  Advertising Router: 10.255.255.13

  LS Seq Number: 8000002A

  Checksum: 0x38B

  Length: 48

  AS Boundary Router

  Number of Links: 2

    Link connected to: a Stub Network

     (Link ID) Network/subnet number: 10.255.255.13

     (Link Data) Network Mask: 255.255.255.255

      Number of TOS metrics: 0

       TOS 0 Metrics: 1

    Link connected to: a Transit Network

     (Link ID) Designated Router address: 172.30.30.13

     (Link Data) Router Interface address: 172.30.30.13

      Number of TOS metrics: 0

       TOS 0 Metrics: 50

Also in case of absence route to 10.255.255.13 in the output of 'sh ip ospf database router' I should got something like - 'Adv Router is not-reachable'.

[MaximBudyonny]

So, as route to 10.255.255.13 is known via static route, but route LSA for this link arrives to R1 I've  removed static route on the R1.

R1(config)no ip route 10.255.255.13 255.255.255.255 172.17.17.10 tag 333 name XXXX

After this manipulation route to 10.10.10.10/32 installs.

R1 (ABR) not only receives LSA type 7 but converts to LSA type 3 and redistributes it the network core.

[Thotsaphon Lueangwattanaphong · Accepted solution]

Hi,

   The forwarding address has to be learnt as intra-area routes and be installed in RIB as O routes. In your case you have a static route for forwarding address that's why you didn't see O N2 on R1.

HTH,

Toshi