Four special regions and configuration of Cisco OSPF

What are the Four special regions of Cisco OSPF ?

1.      Stub area

In the stub area region declined 5 LSA ws-c3560x-24p-s  (can receive inter area routing but not receive the routing), is in the area of the router's routing table is not generated by the ASBR routing, but will generate a default route, which is Ping ASnetwork. But the region within the router must put the region to stub area

Command: R2 (config) #router OS 100------ into the OSPF process

R2 (config-router) #area 1 stub---- area 1 stub area

2.Totally stub area

A. declined to 5 and type 3 LSA in the totally stub area region (in the Ethernetreceive only the routing information, the region's routing does not receive theinter region and outside the region, namely) in the area of the routing table is not used in the inter regional and extra regional route, only the area routing.Note: this will not generate a default route. That is to say within the region isthe region outside the Ping router router. To totally stub area only changes in the region ABR,

Modify command: R2 (config) #router OS 100

R2 (config-router) #area 1 stub no

R2 (config-router) #area 1 stub no-summary

3.Nssa area----- is not totally stubby area (No 5, but have 3 and 7)

A. for stub area, no type 5 LSA in the NSSA region, but there are 3 type LSA and 7 type LSA

B. no area area-id stub must be in the modification of the NSSA region of

The C. used in ABR: SH IP OS will see a 7 LSA to 5 LSA

D. ASBR when allowed to exist a region to the NSSA region, ASBR will produce7 LSA

In NSSA ABR 7 to 5, the ABR will not generate a default route to the NSSAregion

Modify command: R2 (config) #router OS 100

R2 (config-router) #area 1 NSSA

4.Totally nssa----- is not totally stubby area (based on NSSA area to do)

Totally NSSA area based on NSSA area filter type 3 LSA, the default routingand produces a type 3 LSA

Modify command: R2 (config) #router OS 100

R2 (config-router) #area 1 NSSA default-information-originate

Configuration:

The R1 configuration:

r1#sh run
Building configuration...

Current configuration : 1028 bytes
!
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname r1
!
boot-start-marker
boot-end-marker
!
memory-size iomem 5
no aaa new-model
ip subnet-zero
!
no ip domain lookup
!
ip cef
ip ips po max-events 100
no ftp-server write-enable
interface Loopback0
 ip address 1.1.1.1 255.255.255.0
!
interface Serial0/0
 ip address 12.0.0.1 255.255.255.0
 serial restart-delay 0
!
interface Serial0/1
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial0/2
 no ip address
 shutdown
 serial restart-delay 0
!
interface Serial0/3
 no ip address
 shutdown
 serial restart-delay 0
!
router ospf 100
 router-id 1.1.1.1
 log-adjacency-changes
 area 1 stub
 network 1.1.1.0 0.0.0.255 area 1
 network 12.0.0.0 0.0.0.255 area 1
!
ip http server
no ip http secure-server
ip classless
!
control-plane
!        
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
end

r1#sh ip route
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 12.0.0.2 to network 0.0.0.0

     34.0.0.0/24 is subnetted, 1 subnets
O IA    34.0.0.0 [110/192] via 12.0.0.2, 00:03:08, Serial0/0
     1.0.0.0/24 is subnetted, 1 subnets
C       1.1.1.0 is directly connected, Loopback0
     2.0.0.0/32 is subnetted, 1 subnets
O       2.2.2.2 [110/65] via 12.0.0.2, 00:03:08, Serial0/0
     3.0.0.0/32 is subnetted, 1 subnets
O IA    3.3.3.3 [110/129] via 12.0.0.2, 00:03:08, Serial0/0
     4.0.0.0/32 is subnetted, 1 subnets
O IA    4.4.4.4 [110/193] via 12.0.0.2, 00:03:08, Serial0/0
     23.0.0.0/24 is subnetted, 1 subnets
O IA    23.0.0.0 [110/128] via 12.0.0.2, 00:03:08, Serial0/0
     12.0.0.0/24 is subnetted, 1 subnets
C       12.0.0.0 is directly connected, Serial0/0
O*IA 0.0.0.0/0 [110/65] via 12.0.0.2, 00:03:09, Serial0/0

Note: the area 1 is configured for the stub region, ABR (R2) to the regional decentralization of a default route.

The R4 configuration:
r4#sh run
Building configuration...

Current configuration : 1117 bytes
version 12.3
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
hostname r4
boot-start-marker
boot-end-marker
memory-size iomem 5
no aaa new-model
ip subnet-zero
no ip domain lookup
ip cef
ip ips po max-events 100
no ftp-server write-enable
interface Loopback0
 ip address 4.4.4.4 255.255.255.0
interface Loopback1
 ip address 10.0.0.4 255.255.255.0
interface Serial0/0
 ip address 34.0.0.4 255.255.255.0
 serial restart-delay 0
interface Serial0/1
 no ip address
 shutdown
 serial restart-delay 0
interface Serial0/2
 no ip address
 shutdown
 serial restart-delay 0
interface Serial0/3
 no ip address
 shutdown
 serial restart-delay 0!        
router ospf 100
 router-id 4.4.4.4
 log-adjacency-changes
 area 2 nssa
 redistribute connected subnets
 network 4.4.4.0 0.0.0.255 area 2
 network 34.0.0.0 0.0.0.255 area 2
ip http server
no ip http secure-server
ip classless
control-plane!
line con 0
 exec-timeout 0 0
 logging synchronous
line aux 0
line vty 0 4
end

r4# sh ip route
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 34.0.0.3 to network 0.0.0.0

     34.0.0.0/24 is subnetted, 1 subnets
C       34.0.0.0 is directly connected, Serial0/0
     4.0.0.0/24 is subnetted, 1 subnets
C       4.4.4.0 is directly connected, Loopback0
     10.0.0.0/24 is subnetted, 1 subnets
C       10.0.0.0 is directly connected, Loopback1
O*IA 0.0.0.0/0 [110/65] via 34.0.0.3, 00:01:16, Serial0/0
r4#
r4#
Note: the area 2 configuration for the NSSA no-summary region, 7 class LSA and class 3/4/5 filter lsa. ABR (R3) to air-sap2602i-e-k9 area 2 to a default route.

More information about switch and router, please view ：http://www.u-blog.co/h3cswitch/category/3772/cisco-switch