Now you already now OSPF standard area. Lets make stub area!
Before that, what is stub area in OSPF?
- Stub area means router in end point that have area except area backbone and no any connected to another router within OSPF protocol.
- In OSPF all database have the same as within the same area. The advantage using stub area is the database not many as external route LSA type 4 and 5 is not in the routing table.
- Because of that required default route to go to those networks. Using stub area decrease CPU performance and router memory.
- The area using stub need to be configure in all router that have that area.
The topology and basic configuration as the same as OSPF standard area http://pursuingmydestiny.blogspot.com/2011/12/lab-3-ospf-standard-area.html.
In this example we would like to make R3 as the stub area. R3 have area 1... Then all area 1 need being stub area.
R2(config)#router ospf 2
R2(config-router)#area 1 stub
*Mar 1 01:08:30.043: %OSPF-5-ADJCHG: Process 2, Nbr 3.3.3.3 on Serial0/0 from FULL to DOWN, Neighbor Down: Adjacency forced to reset
R3(config)#router ospf 3
R3(config-router)#area 1 stub
*Mar 1 01:08:47.955: %OSPF-5-ADJCHG: Process 3, Nbr 2.2.2.2 on Serial0/0 from FULL to DOWN, Neighbor Down: Adjacency forced to reset
*Mar 1 01:08:52.671: %OSPF-5-ADJCHG: Process 3, Nbr 2.2.2.2 on Serial0/0 from LOADING to FULL, Loading Done
Now, check routing table and LSA in R3
R3(config-router)#do sh ip rout
Codes: 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
Gateway of last resort is 23.23.23.2 to network 0.0.0.0
1.0.0.0/32 is subnetted, 1 subnets
O IA 1.1.1.1 [110/75] via 23.23.23.2, 00:02:14, Serial0/0
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/65] via 23.23.23.2, 00:02:14, Serial0/0
100.0.0.0/32 is subnetted, 3 subnets
O IA 100.100.100.1 [110/75] via 23.23.23.2, 00:02:14, Serial0/0
O IA 100.100.100.2 [110/75] via 23.23.23.2, 00:02:14, Serial0/0
O IA 100.100.100.3 [110/75] via 23.23.23.2, 00:02:14, Serial0/0
3.0.0.0/32 is subnetted, 1 subnets
C 3.3.3.3 is directly connected, Loopback0
23.0.0.0/24 is subnetted, 1 subnets
C 23.23.23.0 is directly connected, Serial0/0
12.0.0.0/24 is subnetted, 1 subnets
O IA 12.12.12.0 [110/74] via 23.23.23.2, 00:02:17, Serial0/0
O*IA 0.0.0.0/0 [110/65] via 23.23.23.2, 00:02:17, Serial0/0
R3(config-router)#do sh ip osp data
OSPF Router with ID (3.3.3.3) (Process ID 3)
Router Link States (Area 1) -----------> LSA Type 1
Link ID ADV Router Age Seq# Checksum Link count
2.2.2.2 2.2.2.2 166 0x80000007 0x00B02D 3
3.3.3.3 3.3.3.3 165 0x80000005 0x00D304 3
Summary Net Link States (Area 1) -----------> LSA Type 3
Link ID ADV Router Age Seq# Checksum
0.0.0.0 2.2.2.2 193 0x80000001 0x0075C0
1.1.1.1 2.2.2.2 193 0x80000003 0x00A77E
12.12.12.0 2.2.2.2 193 0x80000003 0x001AEC
100.100.100.1 2.2.2.2 193 0x80000003 0x00AD4E
100.100.100.2 2.2.2.2 193 0x80000003 0x00A357
100.100.100.3 2.2.2.2 193 0x80000003 0x009960
R3(config-router)#do ping 100.100.100.4
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 100.100.100.4, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 12/50/104 ms
You can see that no any LSA type 4 and 5 in stub area. But I can still ping 100.100.100.4 even no routing table in R3. It's because there is default route created in stub area.
No comments:
Post a Comment