LAB: OSPF Totally Stubby Areas

- Configure area 3 so that R5 filters inter-area ( type3 summary) and External (type5) routes.

Totally-Stubby Areas  filters type 3 Summary LSAs and type 5 External LSAs, totally stubby area optimized the database further by removing the inter-area and external routes.

Note: the "no-summary" keyword is only added to the ABR. though you can configure this also on other routers that belong to the same stub area, but its technically incorrect to configure the other stub routers on this way. As long all stub routers agree on a stub flag then its all ok.

pre-verification before applying the "no-summary" keyword.

Rack1SW4# show ip ospf database

            OSPF Router with ID (150.1.10.10) (Process ID 1)

                Router Link States (Area 3)

Link ID         ADV Router      Age         Seq#       Checksum Link count
150.1.5.5       150.1.5.5       2     (DNA) 0x80000014 0x004C76 3
150.1.8.8       150.1.8.8       1     (DNA) 0x8000000D 0x00E8C8 4
150.1.10.10     150.1.10.10     563         0x8000000A 0x003958 3

                Net Link States (Area 3)

Link ID         ADV Router      Age         Seq#       Checksum
155.1.58.8      150.1.8.8       18    (DNA) 0x80000001 0x000963
155.1.108.10    150.1.10.10     564         0x80000008 0x001C07

                Summary Net Link States (Area 3)

Link ID         ADV Router      Age         Seq#       Checksum
0.0.0.0         150.1.5.5       18    (DNA) 0x80000001 0x001D7F
150.1.1.0       150.1.5.5       18    (DNA) 0x8000000F 0x00230C
150.1.2.0       150.1.5.5       18    (DNA) 0x80000010 0x00B9F9
150.1.3.0       150.1.5.5       18    (DNA) 0x80000010 0x00AE04
150.1.4.0       150.1.5.5       18    (DNA) 0x8000000D 0x00A90B
150.1.6.0       150.1.5.5       18    (DNA) 0x80000006 0x006428
150.1.7.0       150.1.5.5       18    (DNA) 0x80000004 0x005D30
150.1.9.0       150.1.5.5       18    (DNA) 0x80000005 0x0072F9
155.1.0.1       150.1.5.5       18    (DNA) 0x8000000F 0x00D852
155.1.0.2       150.1.5.5       18    (DNA) 0x80000010 0x00703F
155.1.0.3       150.1.5.5       18    (DNA) 0x80000010 0x006648
155.1.0.4       150.1.5.5       18    (DNA) 0x8000000D 0x00624E
155.1.0.5       150.1.5.5       18    (DNA) 0x8000000F 0x00D11C
155.1.6.0       150.1.5.5       18    (DNA) 0x80000004 0x004528
155.1.7.0       150.1.5.5       18    (DNA) 0x80000004 0x005D5A
155.1.9.0       150.1.5.5       18    (DNA) 0x80000005 0x0054F5
155.1.13.0      150.1.5.5       18    (DNA) 0x80000010 0x009ED3
155.1.23.0      150.1.5.5       18    (DNA) 0x80000010 0x009009
155.1.37.0      150.1.5.5       18    (DNA) 0x80000010 0x00AEB0
155.1.45.0      150.1.5.5       18    (DNA) 0x80000011 0x0091F1
155.1.67.0      150.1.5.5       18    (DNA) 0x80000004 0x00A886
155.1.79.0      150.1.5.5       18    (DNA) 0x80000004 0x0024FE
155.1.146.0     150.1.5.5       18    (DNA) 0x80000018 0x00EAFE
192.10.1.0      150.1.5.5       18    (DNA) 0x80000010 0x00EC68

Rack1SW4#show ip route 155.1.9.9
Routing entry for 155.1.9.0/24
  Known via "ospf 1", distance 110, metric 604, type inter area
  Last update from 155.1.108.8 on Port-channel1, 00:41:42 ago
  Routing Descriptor Blocks:
  * 155.1.108.8, from 150.1.5.5, 00:41:42 ago, via Port-channel1
      Route metric is 604, traffic share count is 1

after applying the "area 3 stub no-summary" command.

Rack1SW4# show ip ospf database

            OSPF Router with ID (150.1.10.10) (Process ID 1)

                Router Link States (Area 3)

Link ID         ADV Router      Age         Seq#       Checksum Link count
150.1.5.5       150.1.5.5       2     (DNA) 0x80000014 0x004C76 3
150.1.8.8       150.1.8.8       1     (DNA) 0x8000000D 0x00E8C8 4
150.1.10.10     150.1.10.10     727         0x8000000A 0x003958 3

                Net Link States (Area 3)

Link ID         ADV Router      Age         Seq#       Checksum
155.1.58.8      150.1.8.8       18    (DNA) 0x80000001 0x000963
155.1.108.10    150.1.10.10     728         0x80000008 0x001C07

                Summary Net Link States (Area 3)

Link ID         ADV Router      Age         Seq#       Checksum
0.0.0.0         150.1.5.5       6     (DNA) 0x80000003 0x001981

Rack1SW4#show ip route 155.1.9.9
% Subnet not in table


Rack1SW4#show ip route | inc 0.0.0.0
Gateway of last resort is 155.1.108.8 to network 0.0.0.0
O*IA 0.0.0.0/0 [110/181] via 155.1.108.8, 00:00:36, Port-channel1