NSSA AREA OSPF ISSUE

[Ammartehsein]

I am having issue, I have attached my topology diagram. R2 and R4 are ABRs, R5 is ASBR. Area is nssa. The issue is that on R4 I am receiving route Like expected as N2, But on R2 I received route as External routes E2.

R2=======

6.0.0.0/32 is subnetted, 1 subnets
O E2 6.6.6.6 [110/10] via 192.168.2.5, 00:00:13, Serial1/0
172.16.0.0/24 is subnetted, 3 subnets
O E2 172.16.12.0 [110/10] via 192.168.2.5, 00:00:13, Serial1/0
O E2 172.16.10.0 [110/10] via 192.168.2.5, 00:00:13, Serial1/0
O E2 172.16.11.0 [110/10] via 192.168.2.5, 00:00:13, Serial1/0
7.0.0.0/32 is subnetted, 1 subnets
O IA 7.7.7.7 [110/66] via 20.20.20.3, 00:00:28, FastEthernet0/0
8.0.0.0/32 is subnetted, 1 subnets
O 8.8.8.8 [110/67] via 20.20.20.3, 00:06:07, FastEthernet0/0
9.0.0.0/32 is subnetted, 1 subnets
O IA 9.9.9.9 [110/3] via 20.20.20.3, 00:06:07, FastEthernet0/0
O IA 192.168.5.0/24 [110/66] via 20.20.20.3, 00:00:28, FastEthernet0/0
10.0.0.0/32 is subnetted, 1 subnets
O IA 10.10.10.10 [110/3] via 20.20.20.3, 00:06:07, FastEthernet0/0
O IA 192.168.6.0/24 [110/65] via 20.20.20.3, 00:06:07, FastEthernet0/0
O 192.168.1.0/24 [110/128] via 192.168.2.5, 00:00:28, Serial1/0
C 192.168.2.0/24 is directly connected, Serial1/0
192.168.3.0/32 is subnetted, 3 subnets
O IA 192.168.3.10 [110/2] via 20.20.20.3, 00:06:07, FastEthernet0/0
O IA 192.168.3.9 [110/2] via 20.20.20.3, 00:06:07, FastEthernet0/0
O IA 192.168.3.3 [110/1] via 20.20.20.3, 00:06:07, FastEthernet0/0
O*E2 0.0.0.0/0 [110/1] via 20.20.20.1, 00:06:07, FastEthernet0/0
R2#sh ip route 172.16.12.0
Routing entry for 172.16.12.0/24
Known via "ospf 1", distance 110, metric 10, type extern 2, forward metric 65
Last update from 192.168.2.5 on Serial1/0, 00:00:19 ago
Routing Descriptor Blocks:
* 192.168.2.5, from 4.4.4.4, 00:00:19 ago, via Serial1/0
Route metric is 10, traffic share count is 1

R4=====

2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/2] via 20.20.20.2, 00:13:07, FastEthernet0/0
3.0.0.0/32 is subnetted, 1 subnets
O 3.3.3.3 [110/2] via 20.20.20.3, 00:13:07, FastEthernet0/0
4.0.0.0/32 is subnetted, 1 subnets
C 4.4.4.4 is directly connected, Loopback1
20.0.0.0/24 is subnetted, 2 subnets
C 20.20.20.0 is directly connected, FastEthernet0/0
O 20.20.30.0 [110/66] via 20.20.20.3, 00:13:08, FastEthernet0/0
5.0.0.0/32 is subnetted, 1 subnets
O 5.5.5.5 [110/65] via 192.168.1.5, 00:12:52, Serial1/1
6.0.0.0/32 is subnetted, 1 subnets
O N2 6.6.6.6 [110/10] via 192.168.1.5, 00:12:53, Serial1/1
172.16.0.0/24 is subnetted, 3 subnets
O N2 172.16.12.0 [110/10] via 192.168.1.5, 00:12:53, Serial1/1
O N2 172.16.10.0 [110/10] via 192.168.1.5, 00:12:53, Serial1/1
O N2 172.16.11.0 [110/10] via 192.168.1.5, 00:12:53, Serial1/1
7.0.0.0/32 is subnetted, 1 subnets
O IA 7.7.7.7 [110/66] via 20.20.20.3, 00:12:53, FastEthernet0/0
8.0.0.0/32 is subnetted, 1 subnets
O 8.8.8.8 [110/67] via 20.20.20.3, 00:13:08, FastEthernet0/0
9.0.0.0/32 is subnetted, 1 subnets
O IA 9.9.9.9 [110/3] via 20.20.20.3, 00:13:08, FastEthernet0/0
O IA 192.168.5.0/24 [110/66] via 20.20.20.3, 00:12:53, FastEthernet0/0
10.0.0.0/32 is subnetted, 1 subnets
O IA 10.10.10.10 [110/3] via 20.20.20.3, 00:13:08, FastEthernet0/0
O IA 192.168.6.0/24 [110/65] via 20.20.20.3, 00:13:08, FastEthernet0/0
C 192.168.1.0/24 is directly connected, Serial1/1
O 192.168.2.0/24 [110/128] via 192.168.1.5, 00:12:53, Serial1/1
192.168.3.0/32 is subnetted, 3 subnets
O IA 192.168.3.10 [110/2] via 20.20.20.3, 00:13:08, FastEthernet0/0
O IA 192.168.3.9 [110/2] via 20.20.20.3, 00:13:08, FastEthernet0/0
O IA 192.168.3.3 [110/1] via 20.20.20.3, 00:13:08, FastEthernet0/0
O*E2 0.0.0.0/0 [110/1] via 20.20.20.1, 00:13:08, FastEthernet0/0

R5======

Gateway of last resort is not set

1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/66] via 192.168.2.2, 00:14:20, Serial1/0
[110/66] via 192.168.1.4, 00:13:21, Serial1/1
2.0.0.0/32 is subnetted, 1 subnets
O IA 2.2.2.2 [110/65] via 192.168.2.2, 00:14:20, Serial1/0
3.0.0.0/32 is subnetted, 1 subnets
O IA 3.3.3.3 [110/66] via 192.168.2.2, 00:14:20, Serial1/0
[110/66] via 192.168.1.4, 00:13:21, Serial1/1
4.0.0.0/32 is subnetted, 1 subnets
O IA 4.4.4.4 [110/65] via 192.168.1.4, 00:13:21, Serial1/1
20.0.0.0/24 is subnetted, 2 subnets
O IA 20.20.20.0 [110/65] via 192.168.2.2, 00:14:20, Serial1/0
[110/65] via 192.168.1.4, 00:13:21, Serial1/1
O IA 20.20.30.0 [110/130] via 192.168.2.2, 00:14:21, Serial1/0
[110/130] via 192.168.1.4, 00:13:21, Serial1/1
5.0.0.0/32 is subnetted, 1 subnets
C 5.5.5.5 is directly connected, Loopback0
6.0.0.0/32 is subnetted, 1 subnets
D 6.6.6.6 [90/156160] via 192.168.20.6, 02:19:44, FastEthernet0/0
172.16.0.0/24 is subnetted, 3 subnets
D 172.16.12.0 [90/156160] via 192.168.20.6, 02:19:55, FastEthernet0/0
D 172.16.10.0 [90/156160] via 192.168.20.6, 02:20:02, FastEthernet0/0
D 172.16.11.0 [90/156160] via 192.168.20.6, 02:19:59, FastEthernet0/0
7.0.0.0/32 is subnetted, 1 subnets
O IA 7.7.7.7 [110/130] via 192.168.2.2, 00:14:21, Serial1/0
[110/130] via 192.168.1.4, 00:13:21, Serial1/1
8.0.0.0/32 is subnetted, 1 subnets
O IA 8.8.8.8 [110/131] via 192.168.2.2, 00:14:21, Serial1/0
[110/131] via 192.168.1.4, 00:13:21, Serial1/1
9.0.0.0/32 is subnetted, 1 subnets
O IA 9.9.9.9 [110/67] via 192.168.2.2, 00:14:21, Serial1/0
[110/67] via 192.168.1.4, 00:13:21, Serial1/1
C 192.168.20.0/24 is directly connected, FastEthernet0/0
O IA 192.168.5.0/24 [110/130] via 192.168.2.2, 00:14:21, Serial1/0
[110/130] via 192.168.1.4, 00:13:21, Serial1/1
10.0.0.0/32 is subnetted, 1 subnets
O IA 10.10.10.10 [110/67] via 192.168.2.2, 00:14:21, Serial1/0
[110/67] via 192.168.1.4, 00:13:21, Serial1/1
O IA 192.168.6.0/24 [110/129] via 192.168.2.2, 00:14:21, Serial1/0
[110/129] via 192.168.1.4, 00:13:21, Serial1/1
C 192.168.1.0/24 is directly connected, Serial1/1
C 192.168.2.0/24 is directly connected, Serial1/0
192.168.3.0/32 is subnetted, 3 subnets
O IA 192.168.3.10 [110/66] via 192.168.2.2, 00:14:21, Serial1/0
[110/66] via 192.168.1.4, 00:13:21, Serial1/1
O IA 192.168.3.9 [110/66] via 192.168.2.2, 00:14:21, Serial1/0
[110/66] via 192.168.1.4, 00:13:21, Serial1/1
O IA 192.168.3.3 [110/65] via 192.168.2.2, 00:14:21, Serial1/0
[110/65] via 192.168.1.4, 00:13:21, Serial1/1

[Ammartehsein]

Yes, you are right, but there is some change the router with higher router id will perform translation and router with lower router id will only install O E2. Thanks for help

[MHM Cisco World]

I dont think so.

I run lab and I see both use O N.

Router add O E without receive it from R5??

Share show ip ospf database self in R5 let see what R5 generate 

MHM

[Ammartehsein]

This is R5 output you asked for.

R5#sh ip ospf database self-originate

OSPF Router with ID (5.5.5.5) (Process ID 1)

Router Link States (Area 51)

Link ID ADV Router Age Seq# Checksum Link count
5.5.5.5 5.5.5.5 1578 0x80000039 0x00AFA1 5

Type-7 AS External Link States (Area 51)

Link ID ADV Router Age Seq# Checksum Tag
172.16.10.0 5.5.5.5 1655 0x80000001 0x00C3E3 0
172.16.11.0 5.5.5.5 1655 0x80000001 0x00B8ED 0
172.16.12.0 5.5.5.5 1655 0x80000001 0x00ADF7 0
192.168.20.0 5.5.5.5 1655 0x80000001 0x0029C7 0

[MHM Cisco World]

I get why issue appear' let me try it in lab tonight update ypu later.

MHM

[Giuseppe Larosa]

Hello @Ammartehsein ,

thanks for your feedaback you are welcome. 

Best Regards

Giuseppe

[paul driver]

Hello
Following on from what @Giuseppe Larosa  has stated
As a test for ECMP LB on those external routes you could also set both ABRs to always advertise the forwarding address (FA) based on the rtr 5 Lo0 5.5.5.5 this should then install dual routes for these external prefixes from both ABRs into area 0


R2/4
router ospf x
area 51 nssa translate type7 always
 

[MHM Cisco World]

R5 generate O N2 to both R2/4 
in R2 and R4 when you do 
show ip ospf database nssa-external <<- share this 
also show ip ospf database external 

[MHM Cisco World]

Any update 

MHM