WALKTHROUGH: Network Summary LSAs

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. How many Network Summary LSAs are present in the 101.101.101.101 area?
    2. admin@J2300-1> show ospf database netsummary area 101.101.101.101 summary 
Area 101.101.101.101:
   181 Summary LSAs

admin@J2300-1>
  2. How many Network Summary LSAs are present in the backbone area?
    3. admin@J2300-1> show ospf database netsummary area 0 summary                  
Area 0.0.0.0:
   48 Summary LSAs

admin@J2300-1>
  3. Are there any Network Summary LSAs that match any of the networks present in your Router LSA for the backbone area?
    4. admin@J2300-1> show ospf database router lsa-id 10.0.0.1 area 0 detail | match stub             
  id 10.0.12.0, data 255.255.255.0, Type Stub (3)
  id 10.0.13.0, data 255.255.255.0, Type Stub (3)
  id 10.0.0.1, data 255.255.255.255, Type Stub (3)

admin@J2300-1> show ospf database netsummary area 0 lsa-id 10.0.12.0 

admin@J2300-1> show ospf database netsummary area 0 lsa-id 10.0.13.0    

admin@J2300-1> show ospf database netsummary area 0 lsa-id 10.0.0.1     

admin@J2300-1>
  4. Are there any Network Summary LSAs that match any of the networks present in your Router LSA for the 101.101.101.101 area?
    5. admin@J2300-1> show ospf database netsummary area 101.101.101.101 lsa-id 10.0.12.0   

    OSPF database, Area 101.101.101.101
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Summary *10.0.12.0        10.0.0.1         0x80000001   942  0x22 0x54c2  28
Summary  10.0.12.0        10.0.0.2         0x8000000b  2211  0x22 0x3ad1  28
Summary  10.0.12.0        10.0.0.3         0x80000006  2604  0x22 0x709a  28
Summary  10.0.12.0        10.0.0.4         0x8000000a  2353  0x22 0x62a3  28
Summary  10.0.12.0        10.0.0.5         0x8000000a  2004  0x22 0x8e71  28
Summary  10.0.12.0        10.0.0.6         0x8000000e  1756  0x22 0x807a  28

admin@J2300-1> show ospf database netsummary area 101.101.101.101 lsa-id 10.0.13.0    

    OSPF database, Area 101.101.101.101
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Summary *10.0.13.0        10.0.0.1         0x80000001  1022  0x22 0x49cc  28
Summary  10.0.13.0        10.0.0.2         0x80000008  2110  0x22 0x67a1  28
Summary  10.0.13.0        10.0.0.3         0x80000007  2933  0x22 0x31dc  28
Summary  10.0.13.0        10.0.0.4         0x8000000a  2005  0x22 0x57ad  28
Summary  10.0.13.0        10.0.0.5         0x8000000a  2001  0x22 0x51b2  28
Summary  10.0.13.0        10.0.0.6         0x8000000f  1754  0x22 0x7385  28

admin@J2300-1> show ospf database netsummary area 101.101.101.101 lsa-id 10.0.0.1     

    OSPF database, Area 101.101.101.101
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Summary *10.0.0.1         10.0.0.1         0x80000001  1029  0x22 0x9c8a  28
Summary  10.0.0.1         10.0.0.2         0x80000008  2197  0x22 0xba5f  28
Summary  10.0.0.1         10.0.0.3         0x80000006  2774  0x22 0xb862  28
Summary  10.0.0.1         10.0.0.4         0x8000000e  2173  0x22 0xd438  28
Summary  10.0.0.1         10.0.0.5         0x8000000a  2257  0x22 0xd639  28
Summary  10.0.0.1         10.0.0.6         0x8000000f  2174  0x22 0xf80c  28

admin@J2300-1>
  5. How many Network Summary LSAs are present in the unique area that is attached to each router (0.0.0.1, 0.0.0.2, or 0.0.0.3)?
    6. admin@J2300-1> show ospf database netsummary area 1 summary                 
Area 0.0.0.1:
   52 Summary LSAs

admin@J2300-1>
  6. Summarize to the full extent possible all of the networks in the 0.0.0.1, 0.0.0.2, and 0.0.0.3 networks
    7. 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# set area-range 10.1/16 

[edit protocols ospf area 0.0.0.1]
admin@J2300-1# commit and-quit 
commit complete
Exiting configuration mode

admin@J2300-1>
  7. Find the route that matches your summarized network in the routing table
    8. admin@J2300-1> show route 10.1/16 

inet.0: 39 destinations, 39 routes (39 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

10.1.0.0/16        *[OSPF/10] 01:11:19, metric 16777215
                      Discard
10.1.0.1/32        *[OSPF/150] 04:49:13, metric 0, tag 0
                    > to 10.1.111.101 via fxp1.1001
10.1.14.0/24       *[OSPF/10] 04:49:13, metric 2510
                    > to 10.1.111.101 via fxp1.1001
10.1.23.0/24       *[OSPF/10] 04:49:13, metric 2530
                    > to 10.1.111.101 via fxp1.1001
10.1.34.0/24       *[OSPF/10] 04:49:13, metric 2520
                    > to 10.1.111.101 via fxp1.1001
10.1.111.0/24      *[Direct/0] 04:49:22
                    > via fxp1.1001
10.1.111.1/32      *[Local/0] 04:49:23
                      Local via fxp1.1001
10.1.123.0/24      *[OSPF/10] 04:49:13, metric 2540
                    > to 10.1.111.101 via fxp1.1001

admin@J2300-1>
  8. Examine the Network Summary LSA that your router is using to coalesce routes
    9. admin@J2300-1> show ospf database netsummary area 0 lsa-id 10.1.0.0 advertising-router 10.0.0.1 detail     

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Summary *10.1.0.0         10.0.0.1         0x80000002  1975  0x22 0x2b05  28
  mask 255.255.0.0
  Topology default (ID 0) -> Metric: 2540
  9. Compare the Metric of the LSA to the costs your router has for the networks being summarized
    10. admin@J2300-1> show route 10.1/16 

inet.0: 39 destinations, 39 routes (39 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

10.1.0.0/16        *[OSPF/10] 01:16:07, metric 16777215
                      Discard
10.1.0.1/32        *[OSPF/150] 04:54:01, metric 0, tag 0
                    > to 10.1.111.101 via fxp1.1001
10.1.14.0/24       *[OSPF/10] 04:54:01, metric 2510
                    > to 10.1.111.101 via fxp1.1001
10.1.23.0/24       *[OSPF/10] 04:54:01, metric 2530
                    > to 10.1.111.101 via fxp1.1001
10.1.34.0/24       *[OSPF/10] 04:54:01, metric 2520
                    > to 10.1.111.101 via fxp1.1001
10.1.111.0/24      *[Direct/0] 04:54:10
                    > via fxp1.1001
10.1.111.1/32      *[Local/0] 04:54:11
                      Local via fxp1.1001
10.1.123.0/24      *[OSPF/10] 04:54:01, metric 2540
                    > to 10.1.111.101 via fxp1.1001

admin@J2300-1> show route 10.1/16
  10. Set the metric of your summarized route to a value of 5000
    11. admin@J2300-1> edit                  
Entering configuration mode

[edit]
admin@J2300-1# edit protocols ospf area 0                

[edit protocols ospf area 0.0.0.0]
admin@J2300-1# top                

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

[edit protocols ospf area 0.0.0.1]
admin@J2300-1# set area-range 10.1.0.0/16 override-metric 5000 

[edit protocols ospf area 0.0.0.1]
admin@J2300-1# commit and-quit 
commit complete
Exiting configuration mode
admin@J2300-1> show ospf database netsummary area 0 lsa-id 10.1.0.0 advertising-router 10.0.0.1 detail 

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Summary *10.1.0.0         10.0.0.1         0x80000003    91  0x22 0x97f1  28
  mask 255.255.0.0
  Topology default (ID 0) -> Metric: 5000

admin@J2300-1>
  11. How many Network Summary LSAs are present in the 101.101.101.101 area?
    12. admin@J2300-1> show ospf database netsummary area 101.101.101.101 summary 
Area 101.101.101.101:
   109 Summary LSAs
  12. How many Network Summary LSAs are present in the backbone area?
    13. admin@J2300-1> ... ospf database netsummary area 0 summary                  
Area 0.0.0.0:
   24 Summary LSAs
  13. Block the 10.102.0.0/24 network in area 102.102.102.102 from being advertised into the backbone or any other areas
    14. admin@J2300-1>show ospf database netsummary area 0 lsa-id 10.102.0.0 advertising-router 10.0.0.1                 

    OSPF database, Area 0.0.0.0
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Summary *10.102.0.0       10.0.0.1         0x8000000b   113  0x22 0xc623  28

admin@J2300-1> edit  
Entering configuration mode

[edit]
admin@J2300-1# edit protocols ospf area 102.102.102.102 

[edit protocols ospf area 102.102.102.102]
admin@J2300-1# set area-range 10.102.0.0/24 restrict 

[edit protocols ospf area 102.102.102.102]
admin@J2300-1# run show ospf database netsummary area 0 lsa-id 10.102.0.0 advertising-router 10.0.0.1 

[edit protocols ospf area 102.102.102.102]
admin@J2300-1#
  14. Attempt to summarize all of the 10.101/16 address space in the backbone as it is advertised into the other areas. Why didn't it work?
    15. admin@J2300-1# run show ospf database netsummary area 1 lsa-id 10.101.0.0 advertising-router 10.0.0.1       

    OSPF database, Area 0.0.0.1
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Summary *10.101.0.0       10.0.0.1         0x8000000c   189  0x22 0xd019  28

[edit]
admin@J2300-1# edit protocols ospf area 0 

[edit protocols ospf area 0.0.0.0]
admin@J2300-1# set area-range 10.101/16 

[edit protocols ospf area 0.0.0.0]
admin@J2300-1# commit 
commit complete

[edit protocols ospf area 0.0.0.0]
admin@J2300-1# run show ospf database netsummary area 1 lsa-id 10.101.0.0 advertising-router 10.0.0.1      
    OSPF database, Area 0.0.0.1
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len 
Summary *10.101.0.0       10.0.0.1         0x8000000c   272  0x22 0xd019  28

[edit protocols ospf area 0.0.0.0]
admin@J2300-1#

    It didn't work because an ABR can only summarize network information from Type 1 and Type 2 LSAs. It cannot summarize Type 3 LSAs.