Totally Stub Area – No Type 5 External LSA and Type 3 Summary LSA . There were also no ASBR. By configuring “area

Not-So-Stubby-Area – NSSA is quite different in a sense that it does NOT allow Type 5 LSA but is allowing ASBR. We have seen from the previous laboratory that the router linking the backbone and the NSSA becomes the ASBR. On this ASBR, we have seen both the Type 7 LSA and the Type 5 LSA (Redistributed routes into OSPF). By just enabling “area 

Now, in my notes for Totally NSSA, I will be sharing about the characteristics of this area type. Totally NSSA does not allow Type 5 LSA and Type 3 LSA but it does allow an ASBR. So it means that by just simply enabling “area

 Here is my topology for my laboratory,

 Laboratory Objective:

1. To enabled OSPF as per the topology above.

2. To proved that ONLY the default route is installed on SINGAPORE routing table after enabling 
” area

Here are my routers OSPF configurations.

MANILA#sh run | sec ospf
router ospf 1
 network 10.10.10.0 0.0.0.255 area 3
 network 10.10.11.0 0.0.0.255 area 3
 network 10.10.12.0 0.0.0.255 area 3
 network 10.10.13.0 0.0.0.255 area 3
 network 192.168.12.0 0.0.0.255 area 0
 network 192.168.14.0 0.0.0.255 area 2
MELBOURNE#sh run | sec ospf
router ospf 1
 network 20.20.20.0 0.0.0.255 area 0
 network 192.168.12.0 0.0.0.255 area 0
 network 192.168.23.0 0.0.0.255 area 1

SINGAPORE#sh run | sec ospf
router ospf 1
 network 30.30.30.0 0.0.0.255 area 1
 network 192.168.23.0 0.0.0.255 area 1

SYDNEY#sh run | sec ospf
router ospf 1
 network 40.40.40.0 0.0.0.255 area 2
 network 192.168.14.0 0.0.0.255 area 2
SYDNEY#

Verifications:

SINGAPORE#sh ip ospf database

Link ID         ADV Router      Age         Seq#       Checksum Tag
40.40.40.0      40.40.40.1      25          0x80000001 0x007836 0
SINGAPORE#

Observations:

1. The redistributed network from SYDNEY is showing as Type 5 AS External LSA.

2. I have two Type 4 ASBR Summary LSA  (10.10.12.1 & 40.40.40.1)

3. I have also a Type 3 Summary LSA for the networks advertised into OSPF by both the MANILA and MELBOURNE, and the links between SYDNEY & MANILA and MANILA & MELBOURNE routers.

4.  I would also have the regular Router LSA or the Type 1 LSA.

So what’s inside SINGAPORE routing table,

 SINGAPORE#show ip route ospf
Codes: L – local, C – connected, S – static, R – RIP, M – mobile, B – BGP
       D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
       N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
       E1 – OSPF external type 1, E2 – OSPF external type 2
       i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
       ia – IS-IS inter area, * – candidate default, U – per-user static route
       o – ODR, P – periodic downloaded static route, H – NHRP, l – LISP
       + – replicated route, % – next hop override

      10.0.0.0/32 is subnetted, 4 subnets
O IA     10.10.10.1 [110/129] via 192.168.23.2, 00:14:56, Serial3/1
O IA     10.10.11.1 [110/129] via 192.168.23.2, 00:14:56, Serial3/1
O IA     10.10.12.1 [110/129] via 192.168.23.2, 00:14:56, Serial3/1
O IA     10.10.13.1 [110/129] via 192.168.23.2, 00:14:56, Serial3/1
      20.0.0.0/32 is subnetted, 1 subnets
O IA     20.20.20.1 [110/65] via 192.168.23.2, 00:14:56, Serial3/1
      40.0.0.0/24 is subnetted, 1 subnets
O E2     40.40.40.0 [110/20] via 192.168.23.2, 00:10:46, Serial3/1    <<<< This is the Type 5 LSA ( OSPF External Type 2 routes)
O IA  192.168.12.0/24 [110/128] via 192.168.23.2, 00:14:56, Serial3/1
O IA  192.168.14.0/24 [110/192] via 192.168.23.2, 00:14:56, Serial3/1
SINGAPORE#

 Observations:

1. So we have the redistributed routes labelled as O E2 which are Type-5 AS External LSA.

2.  The rest are Inter-Area Routes from all the OSPF Areas. 
 

Let’s check what we have in MELBOURNE router,

MELBOURNE#show ip ospf database

Link ID         ADV Router      Age         Seq#       Checksum Tag
40.40.40.0      40.40.40.1      583         0x80000001 0x007836 0
MELBOURNE#

Observations:

1. So we have the Type 5 AS External LSA for SYDNEY redistributed network.

2.  We have as well the Type 4 ASBR Summary LSA ( this means that both SYDNEY & MANILA are ASBR ). 

 Now, let’s check the routing table,

 MELBOURNE#show ip route ospf
Codes: L – local, C – connected, S – static, R – RIP, M – mobile, B – BGP
       D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
       N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
       E1 – OSPF external type 1, E2 – OSPF external type 2
       i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
       ia – IS-IS inter area, * – candidate default, U – per-user static route
       o – ODR, P – periodic downloaded static route, H – NHRP, l – LISP
       + – replicated route, % – next hop override

      10.0.0.0/32 is subnetted, 4 subnets
O IA     10.10.10.1 [110/65] via 192.168.12.1, 00:24:39, Serial3/0
O IA     10.10.11.1 [110/65] via 192.168.12.1, 00:24:39, Serial3/0
O IA     10.10.12.1 [110/65] via 192.168.12.1, 00:24:39, Serial3/0
O IA     10.10.13.1 [110/65] via 192.168.12.1, 00:24:39, Serial3/0
      30.0.0.0/32 is subnetted, 1 subnets
O        30.30.30.1 [110/65] via 192.168.23.3, 00:24:09, Serial3/1
      40.0.0.0/24 is subnetted, 1 subnets
O E2     40.40.40.0 [110/20] via 192.168.12.1, 00:20:10, Serial3/0
O IA  192.168.14.0/24 [110/128] via 192.168.12.1, 00:24:39, Serial3/0
MELBOURNE#


 Observations:

1. So I have the External Type 2 OSPF routes also from SYDNEY which is reachable via MANILA.

2. I have as well the Inter-Area routes from Area 1, Area 3 and Area 2.

NOW, LET’S CHANGE BOTH THE MELBOURNE & SINGAPORE Routers into a TOTALLY NSSA routers.


MELBOURNE(config)#router ospf 1
MELBOURNE(config-router)#area 1 nssa no-summary
MELBOURNE(config-router)#
*Aug  2 11:58:17.211: %OSPF-5-ADJCHG: Process 1, Nbr 30.30.30.1 on Serial3/1 from FULL to DOWN, Neighbor Down: Adjacency forced to reset
MELBOURNE(config-router)#
*Aug  2 11:58:44.419: %OSPF-5-ADJCHG: Process 1, Nbr 30.30.30.1 on Serial3/1 from LOADING to FULL, Loading Done
MELBOURNE(config-router)#

SINGAPORE(config)#router ospf 1
SINGAPORE(config-router)#area 1 nssa no-summary ?
  default-information-originate  Originate Type 7 default into NSSA area
  no-ext-capability              Do not send domain specific capabilities into
                                 NSSA
  no-redistribution              No redistribution into this NSSA area
  translate                      Translate LSA
 

SINGAPORE(config-router)#area 1 nssa no-summary
SINGAPORE(config-router)#
*Aug  2 11:58:42.299: %OSPF-5-ADJCHG: Process 1, Nbr 20.20.20.1 on Serial3/1 from FULL to DOWN, Neighbor Down: Adjacency forced to reset
SINGAPORE(config-router)#
*Aug  2 11:58:44.391: %OSPF-5-ADJCHG: Process 1, Nbr 20.20.20.1 on Serial3/1 from LOADING to FULL, Loading Done
SINGAPORE(config-router)#

Observation:

1. It’s interesting to note that once we enabled ” area 1 nssa no-summary ” it does resets the OSPF adjacencies.

2. Second, as we can see there was an option for “default-information-originate” for Totally NSSA. But let’s see what happens to the routing table on SINGAPORE router.

SINGAPORE#show ip route ospf
Codes: L – local, C – connected, S – static, R – RIP, M – mobile, B – BGP
       D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
       N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
       E1 – OSPF external type 1, E2 – OSPF external type 2
       i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
       ia – IS-IS inter area, * – candidate default, U – per-user static route
       o – ODR, P – periodic downloaded static route, H – NHRP, l – LISP
       + – replicated route, % – next hop override

O*IA  0.0.0.0/0 [110/65] via 192.168.23.2, 00:04:12, Serial3/1
SINGAPORE#

3. As observed above, the default-information-originate command is NO LONGER required for Totally NSSA unlike NSSA which is required to advertise the default routes to other NSSA routers except for the ASBR or teh ABR.

4. With a single entry on the routing table, it means, I would see only a Router LSA and Type 3 LSA with a 0.0.0.0 LINK ID.

SINGAPORE#show ip ospf database

Link ID         ADV Router      Age         Seq#       Checksum
0.0.0.0         20.20.20.1      545         0x80000001 0x0051A7
SINGAPORE# 

Let me show what’s the Routing Table and OSPF database entries of MELBOURNE,

MELBOURNE#show ip route ospf
Codes: L – local, C – connected, S – static, R – RIP, M – mobile, B – BGP
       D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
       N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
       E1 – OSPF external type 1, E2 – OSPF external type 2
       i – IS-IS, su – IS-IS summary, L1 – IS-IS level-1, L2 – IS-IS level-2
       ia – IS-IS inter area, * – candidate default, U – per-user static route
       o – ODR, P – periodic downloaded static route, H – NHRP, l – LISP
       + – replicated route, % – next hop override

      10.0.0.0/32 is subnetted, 4 subnets
O IA     10.10.10.1 [110/65] via 192.168.12.1, 00:10:56, Serial3/0
O IA     10.10.11.1 [110/65] via 192.168.12.1, 00:10:56, Serial3/0
O IA     10.10.12.1 [110/65] via 192.168.12.1, 00:10:56, Serial3/0
O IA     10.10.13.1 [110/65] via 192.168.12.1, 00:10:56, Serial3/0
      30.0.0.0/32 is subnetted, 1 subnets
O        30.30.30.1 [110/65] via 192.168.23.3, 00:10:24, Serial3/1
      40.0.0.0/24 is subnetted, 1 subnets
O E2     40.40.40.0 [110/20] via 192.168.12.1, 00:10:56, Serial3/0
O IA  192.168.14.0/24 [110/128] via 192.168.12.1, 00:10:56, Serial3/0
MELBOURNE#

Observations:

1.  So MELBOURNE does NOT have the default route but rather the Inter-Area Routes and the External Type 2 OSPF Routes. This is quite INTERESTING because on MELBOURNE’S LSDB, it shows an entries for Type 3 Summary LSA with a LINK ID of 0.0.0.0 which is advertise by MELBOURNE router itself.


 MELBOURNE#show ip ospf database

Link ID         ADV Router      Age         Seq#       Checksum Tag
40.40.40.0      40.40.40.1      488         0x80000002 0x007637 0
MELBOURNE#

2. Another observation from MELBOURNE’s routing information and LSDB details, Type 5 AS External LSA’s and Type 4 ASBR Summary LSA’s were present but this is not available on SINGAPORE router. So it does proved our previous discussion that TYPE 5 LSA’S are only available  on the ABR (or ASBR) but not on other Totally NSSA member routers.

3. There will no changes on the existing LSDB of both SYDNEY and MANILA routers.


Connectivity Testing:


Ping from SYDNEY to MANILA Router.
 
SYDNEY#ping 30.30.30.1 source 40.40.40.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 30.30.30.1, timeout is 2 seconds:
Packet sent with a source address of 40.40.40.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 124/140/168 ms

SYDNEY#traceroute 30.30.30.1
Type escape sequence to abort.
Tracing the route to 30.30.30.1
VRF info: (vrf in name/id, vrf out name/id)
  1 192.168.14.1 72 msec 92 msec 124 msec
  2 192.168.12.2 200 msec 120 msec 228 msec
  3 192.168.23.3 260 msec 212 msec 220 msec
SYDNEY#

Ping from SYDNEY to MANILA Router.

SYDNEY#ping 10.10.10.1 source 40.40.40.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.10.10.1, timeout is 2 seconds:
Packet sent with a source address of 40.40.40.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 72/88/92 ms


Ping from SINGAPORE to MANILA Router.

 SINGAPORE#ping 20.20.20.1 source 30.30.30.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 20.20.20.1, timeout is 2 seconds:
Packet sent with a source address of 30.30.30.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 88/95/100 ms
SINGAPORE#