WALKTHROUGH: NSSAs

So you're stuck or don't trust your work. Here is the cheat/check page. Note that this is all done from the perspective of J2300-1. Adapt to other routers as needed.

  1. Reconfigure areas 0.0.0.1, 0.0.0.2 and 0.0.0.3 as a stub area
    2. [edit]
admin@J2300-1# set protocols ospf area 1 nssa 

[edit]
admin@J2300-1# commit 
commit complete

[edit]
admin@J2300-1#

    Same configuration tasks done on R1-R4.

  2. How many NSSA LSAs exist in the backbone, and the NSSA attached to your router?
    3. admin@J2300-1> show ospf database nssa summary   
Area 0.0.0.0:
Area 0.0.0.1:
   13 NSSA LSAs
Area 30.30.30.30:
Area 101.101.101.101:
Area 102.102.102.102:

admin@J2300-1>
  3. How many Network Summary LSAs exist in the NSSA attached to your router?
    4. admin@J2300-1> show ospf database netsummary summary 
Area 0.0.0.0:
   23 Summary LSAs
Area 0.0.0.1:
   18 Summary LSAs
Area 30.30.30.30:
   107 Summary LSAs
Area 101.101.101.101:
   108 Summary LSAs
Area 102.102.102.102:
   109 Summary LSAs

admin@J2300-1>
  4. Inspect one of the NSSA LSAs that contains routing information for the 3.3.3.0/24, 4.4.4.0/24, 5.5.5.0/24, 7.7.7.0/24, 11.11.11.0/24, or 12.12.12.0/24 networks in detail
    5. admin@J2300-1> show ospf database nssa lsa-id 3.3.3.0 detail 

    OSPF database, Area 0.0.0.1
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
NSSA     3.3.3.0          10.1.0.3         0x80000005  2069  0x28 0xe4b5  36
  mask 255.255.255.0
  Topology default (ID 0)
    Type: 1, Metric: 100, Fwd addr: 10.1.0.3, Tag: 0.0.0.3

admin@J2300-1>
  5. Find the corresponding External LSA present in the backbone, and in area 101.101.101.101
    6. admin@J2300-1> show ospf database external lsa-id 3.3.3.0 detail 
    OSPF AS SCOPE link state database
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Extern   3.3.3.0          10.0.0.3         0x80000004  2388  0x22 0x653f  36
  mask 255.255.255.0
  Topology default (ID 0)
    Type: 1, Metric: 100, Fwd addr: 10.1.0.3, Tag: 0.0.0.3

admin@J2300-1>
  6. What is the forwarding address set to?
    7. admin@J2300-1> show ospf database external lsa-id 3.3.3.0 detail | match Fwd                    
    Type: 1, Metric: 100, Fwd addr: 10.1.0.3, Tag: 0.0.0.3

admin@J2300-1>
  7. Is there an ASBR summary route announcing the presence of the NSSA ASBR that originated the route?
    8. admin@J2300-1> show ospf database asbrsummary lsa-id 10.1.0.3 

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
ASBRSum *10.1.0.3         10.0.0.1         0x80000005  2545  0x22 0xcbad  28
ASBRSum  10.1.0.3         10.0.0.3         0x80000006  2348  0x22 0xbd86  28

    OSPF database, Area 30.30.30.30
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
ASBRSum *10.1.0.3         10.0.0.1         0x80000005  2514  0x22 0xcbad  28
ASBRSum  10.1.0.3         10.0.0.2         0x80000004  2340  0x22 0x2c11  28
ASBRSum  10.1.0.3         10.0.0.3         0x80000006  2322  0x22 0xbd86  28
ASBRSum  10.1.0.3         10.0.0.4         0x80000004  2279  0x22 0xed52  28
ASBRSum  10.1.0.3         10.0.0.5         0x80000004  2326  0x22 0xe757  28
ASBRSum  10.1.0.3         10.0.0.6         0x80000004  2459  0x22 0x1425  28

    OSPF database, Area 101.101.101.101
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
ASBRSum *10.1.0.3         10.0.0.1         0x80000005  2484  0x22 0xcbad  28
ASBRSum  10.1.0.3         10.0.0.2         0x80000004  2313  0x22 0x2c11  28
ASBRSum  10.1.0.3         10.0.0.3         0x80000006  2297  0x22 0xbd86  28
ASBRSum  10.1.0.3         10.0.0.4         0x80000004  2251  0x22 0xed52  28
ASBRSum  10.1.0.3         10.0.0.5         0x80000004  2299  0x22 0xe757  28
ASBRSum  10.1.0.3         10.0.0.6         0x80000004  2432  0x22 0x1425  28
                                        
    OSPF database, Area 102.102.102.102
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
ASBRSum *10.1.0.3         10.0.0.1         0x80000005  2453  0x22 0xcbad  28
ASBRSum  10.1.0.3         10.0.0.2         0x80000004  2286  0x22 0x2c11  28
ASBRSum  10.1.0.3         10.0.0.3         0x80000006  2271  0x22 0xbd86  28
ASBRSum  10.1.0.3         10.0.0.4         0x80000004  2224  0x22 0xed52  28
ASBRSum  10.1.0.3         10.0.0.5         0x80000004  2271  0x22 0xe757  28
ASBRSum  10.1.0.3         10.0.0.6         0x80000004  2405  0x22 0x1425  28

admin@J2300-1>
  8. Disable sending summary routes into areas 0.0.0.1, 0.0.0.2 and 0.0.0.3
    9. admin@J2300-1> edit 
Entering configuration mode

[edit]
admin@J2300-1# set protocols ospf area 1 nssa no-summaries 

[edit]
admin@J2300-1# commit 
commit complete

[edit]
admin@J2300-1#
  9. Finish configuration of both ABRs in each area and check how many Network Summary LSAs are in the area
    10. admin@J2300-1> show ospf database netsummary summary 
Area 0.0.0.0:
   23 Summary LSAs
Area 0.0.0.1:
Area 30.30.30.30:
   107 Summary LSAs
Area 101.101.101.101:
   108 Summary LSAs
Area 102.102.102.102:
   109 Summary LSAs

admin@J2300-1> 
[edit]
  10. Check the routing table of one of the internal routers in the 0.0.0.1, 0.0.0.2 or 0.0.0.3 areas
    11. R3@LR:R3> show route | no-more    

inet.0: 24 destinations, 24 routes (24 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

3.3.3.0/24         *[Static/5] 06:11:16
                      Receive
3.3.33.0/24        *[Static/5] 00:19:06
                      Receive
3.33.3.0/24        *[Static/5] 00:18:48
                      Receive
3.33.33.0/24       *[Static/5] 00:18:48
                      Receive
4.4.4.0/24         *[OSPF/150] 02:21:16, metric 1000, tag 4
                    > to 10.1.23.102 via fxp5.123
4.4.44.0/24        *[OSPF/150] 00:17:39, metric 1000, tag 4
                    > to 10.1.23.102 via fxp5.123
4.44.4.0/24        *[OSPF/150] 00:17:39, metric 1000, tag 4
                    > to 10.1.23.102 via fxp5.123
4.44.44.0/24       *[OSPF/150] 00:17:39, metric 1000, tag 4
                    > to 10.1.23.102 via fxp5.123
5.1.1.0/25         *[OSPF/150] 02:21:16, metric 2521, tag 1
                    > to 10.1.23.102 via fxp5.123
5.1.3.0/25         *[OSPF/150] 02:21:16, metric 21, tag 1
                    > to 10.1.23.102 via fxp5.123
5.2.1.0/25         *[OSPF/150] 02:21:16, metric 2, tag 2
                    > to 10.1.23.102 via fxp5.123
5.2.3.0/25         *[OSPF/150] 02:21:16, metric 2, tag 2
                    > to 10.1.23.102 via fxp5.123
10.1.0.1/32        *[OSPF/10] 02:21:16, metric 5020
                    > to 10.1.23.102 via fxp5.123
10.1.0.2/32        *[OSPF/10] 02:21:33, metric 10
                    > to 10.1.23.102 via fxp5.123
10.1.0.3/32        *[Direct/0] 06:11:15
                    > via lo0.103
10.1.0.4/32        *[OSPF/10] 02:21:16, metric 5030
                    > to 10.1.23.102 via fxp5.123
10.1.14.0/24       *[OSPF/10] 02:21:16, metric 5030
                    > to 10.1.23.102 via fxp5.123
10.1.23.0/24       *[Direct/0] 02:28:31
                    > via fxp5.123
10.1.23.103/32     *[Local/0] 06:11:15
                      Local via fxp5.123
10.1.34.0/24       *[Direct/0] 02:28:31
                    > via fxp5.134
10.1.34.103/32     *[Local/0] 06:11:15
                      Local via fxp5.134
10.1.111.0/24      *[OSPF/10] 02:21:16, metric 5020
                    > to 10.1.23.102 via fxp5.123
10.1.123.0/24      *[OSPF/10] 02:21:33, metric 20
                    > to 10.1.23.102 via fxp5.123
224.0.0.5/32       *[OSPF/10] 06:11:16, metric 1
                      MultiRecv

R3@LR:R3>
  11. Inject a default route with a metric of 1000 into each NSSA area from the ABRs
    12. [edit protocols ospf area 0.0.0.1]
admin@J2300-1# set nssa default-lsa default-metric 1000 

[edit protocols ospf area 0.0.0.1]
admin@J2300-1# commit 
commit complete

[edit protocols ospf area 0.0.0.1]
admin@J2300-1# 
[edit]
  12. Again, configure both ABRs for each area and check how many Network Summary LSAs are in the area
    13. admin@J2300-1> show ospf database netsummary summary    
Area 0.0.0.0:
   23 Summary LSAs
Area 0.0.0.1:
   2 Summary LSAs
Area 30.30.30.30:
   107 Summary LSAs
Area 101.101.101.101:
   108 Summary LSAs
Area 102.102.102.102:
   109 Summary LSAs

admin@J2300-1>
  13. Again, check the routing table of one of the internal routers in the 0.0.0.1, 0.0.0.2 or 0.0.0.3 areas
    14. R3@LR:R3> show route | no-more    

inet.0: 25 destinations, 25 routes (25 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

0.0.0.0/0          *[OSPF/10] 00:00:53, metric 3520
                    > to 10.1.23.102 via fxp5.123
3.3.3.0/24         *[Static/5] 06:13:02
                      Receive
3.3.33.0/24        *[Static/5] 00:20:52
                      Receive
3.33.3.0/24        *[Static/5] 00:20:34
                      Receive
3.33.33.0/24       *[Static/5] 00:20:34
                      Receive
4.4.4.0/24         *[OSPF/150] 02:23:02, metric 1000, tag 4
                    > to 10.1.23.102 via fxp5.123
4.4.44.0/24        *[OSPF/150] 00:19:25, metric 1000, tag 4
                    > to 10.1.23.102 via fxp5.123
4.44.4.0/24        *[OSPF/150] 00:19:25, metric 1000, tag 4
                    > to 10.1.23.102 via fxp5.123
4.44.44.0/24       *[OSPF/150] 00:19:25, metric 1000, tag 4
                    > to 10.1.23.102 via fxp5.123
5.1.1.0/25         *[OSPF/150] 02:23:02, metric 2521, tag 1
                    > to 10.1.23.102 via fxp5.123
5.1.3.0/25         *[OSPF/150] 02:23:02, metric 21, tag 1
                    > to 10.1.23.102 via fxp5.123
5.2.1.0/25         *[OSPF/150] 02:23:02, metric 2, tag 2
                    > to 10.1.23.102 via fxp5.123
5.2.3.0/25         *[OSPF/150] 02:23:02, metric 2, tag 2
                    > to 10.1.23.102 via fxp5.123
10.1.0.1/32        *[OSPF/10] 02:23:02, metric 5020
                    > to 10.1.23.102 via fxp5.123
10.1.0.2/32        *[OSPF/10] 02:23:19, metric 10
                    > to 10.1.23.102 via fxp5.123
10.1.0.3/32        *[Direct/0] 06:13:01
                    > via lo0.103
10.1.0.4/32        *[OSPF/10] 02:23:02, metric 5030
                    > to 10.1.23.102 via fxp5.123
10.1.14.0/24       *[OSPF/10] 02:23:02, metric 5030
                    > to 10.1.23.102 via fxp5.123
10.1.23.0/24       *[Direct/0] 02:30:17
                    > via fxp5.123
10.1.23.103/32     *[Local/0] 06:13:01
                      Local via fxp5.123
10.1.34.0/24       *[Direct/0] 02:30:17
                    > via fxp5.134
10.1.34.103/32     *[Local/0] 06:13:01
                      Local via fxp5.134
10.1.111.0/24      *[OSPF/10] 02:23:02, metric 5020
                    > to 10.1.23.102 via fxp5.123
10.1.123.0/24      *[OSPF/10] 02:23:19, metric 20
                    > to 10.1.23.102 via fxp5.123
224.0.0.5/32       *[OSPF/10] 06:13:02, metric 1
                      MultiRecv

R3@LR:R3>
  14. Locate the LSA announcing the default route
    15. admin@J2300-1> show ospf database lsa-id 0.0.0.0 area 1 detail 

    OSPF database, Area 0.0.0.1
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Summary *0.0.0.0          10.0.0.1         0x80000001   549  0x20 0x7bcc  28
  mask 0.0.0.0
  Topology default (ID 0) -> Metric: 1000
Summary  0.0.0.0          10.0.0.3         0x80000001    52  0x20 0x6fd6  28
  mask 0.0.0.0
  Topology default (ID 0) -> Metric: 1000

admin@J2300-1> 
[edit]
  15. Eliminate all of the Network Summary LSAs in areas 0.0.0.1, 0.0.0.2 and 0.0.0.3 by changing the announcement for the default route to a NSSA LSA that has a metric of 1000 and takes into consideration the cost from the NSSA ABR to the NSSA ASBR
    16. admin@J2300-1> edit 
Entering configuration mode

[edit]
admin@J2300-1# edit protocols ospf area 1 

[edit protocols ospf area 0.0.0.1]
admin@J2300-1# edit nssa default-lsa 

[edit protocols ospf area 0.0.0.1 nssa default-lsa]
admin@J2300-1# set type-7 

[edit protocols ospf area 0.0.0.1 nssa default-lsa]
admin@J2300-1# commit 
commit complete

[edit protocols ospf area 0.0.0.1 nssa default-lsa]
admin@J2300-1# top       

[edit]
admin@J2300-1# edit protocols ospf area 1 nssa default-lsa 

[edit protocols ospf area 0.0.0.1 nssa default-lsa]
admin@J2300-1# set type-7 

[edit protocols ospf area 0.0.0.1 nssa default-lsa]
admin@J2300-1# set metric-type 1                            

[edit protocols ospf area 0.0.0.1 nssa default-lsa]
admin@J2300-1# commit 
commit complete

[edit protocols ospf area 0.0.0.1 nssa default-lsa]
admin@J2300-1# 
[edit]
  16. Because counting LSAs is so fun, how many Network Summary LSAs and are in your area now
    17. admin@J2300-1> show ospf database netsummary summary     
Area 0.0.0.0:
   23 Summary LSAs
Area 0.0.0.1:
Area 30.30.30.30:
   107 Summary LSAs
Area 101.101.101.101:
   108 Summary LSAs
Area 102.102.102.102:
   109 Summary LSAs

admin@J2300-1>
  17. Reinspect the 0.0.0.0 LSAs in your area
    18. admin@J2300-1> show ospf database area 1 lsa-id 0.0.0.0 detail 

    OSPF database, Area 0.0.0.1
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
NSSA    *0.0.0.0          10.0.0.1         0x80000001   263  0x20 0x53e8  36
  mask 0.0.0.0
  Topology default (ID 0)
    Type: 1, Metric: 1000, Fwd addr: 0.0.0.0, Tag: 0.0.0.0
NSSA     0.0.0.0          10.0.0.3         0x80000001   116  0x20 0x47f2  36
  mask 0.0.0.0
  Topology default (ID 0)
    Type: 1, Metric: 1000, Fwd addr: 0.0.0.0, Tag: 0.0.0.0

admin@J2300-1> 
[edit]
  18. Consolidate all of the external route advertisements into the 3/8, 4/8, 5/8, 7/8, 11/8 and 12/8 networks
    19. admin@J2300-1> edit 
Entering configuration mode

[edit]
admin@J2300-1# edit protocols ospf area 1 nssa 

[edit protocols ospf area 0.0.0.1 nssa]
admin@J2300-1# set area-range 3/8 

[edit protocols ospf area 0.0.0.1 nssa]
admin@J2300-1# set area-range 4/8 

[edit protocols ospf area 0.0.0.1 nssa]
admin@J2300-1# commit 
commit complete

[edit protocols ospf area 0.0.0.1 nssa]
admin@J2300-1# 
[edit]
  19. Inspect an external LSA for one of the 3/8, 4/8, 5/8, 7/8, 11/8 and 12/8 networks
    20. admin@J2300-1> show ospf database external lsa-id 4.0.0.0 detail      
    OSPF AS SCOPE link state database
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Extern   4.0.0.0          10.0.0.3         0x80000001   185  0x22 0x9e16  36
  mask 255.0.0.0
  Topology default (ID 0)
    Type: 2, Metric: 1001, Fwd addr: 0.0.0.0, Tag: 0.0.0.0

admin@J2300-1> 
[edit]
  20. What is the forwarding address in the External LSA?
    21. admin@J2300-1> show ospf database external lsa-id 4.0.0.0 detail | match Fwd                    
    Type: 2, Metric: 1001, Fwd addr: 0.0.0.0, Tag: 0.0.0.0

admin@J2300-1>