Summarization on ASBR

LAB17: OSPF – IPv4

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LAB 17: Diagram

Note: This Lab was developed on Cisco IOS Version15.2(4) M1 ADVENTERPRISEK9-M.

LAB 3: OSPF Summarization on ASBR 

Task 1: Configure IPv4 OSPF Summarization 

• In the configuration mode of router configure 4 loopbacks with network address in sequence 

R1:

interface loopback 100

ip address 100.0.0.1 255.255.255.0

exit

interface loopback 101 

ip address 100.0.1.1 255.255.255.0

exit

interface loopback 102 

ip address 100.0.2.1 255.255.255.0

exit

interface loopback 103 

ip address 100.0.3.1 255.255.255.0

exit

Step 2  Redistribute external 100 network on ASBR.

R1:

router ospf 1

redistribute connected subnets

(Redistributed connected will redistribute its connected network. Subnet will allow classless routes in OSPF process.)

Step 3  Verify routes on neighbor router routing table

R2#show ip route

! (Shows router’s routing table and IPv4 entries)

Codes: L – local, 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, H – NHRP, l – LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

      11.0.0.0/32 is subnetted, 3 subnets

O        11.0.1.1 [110/65] via 12.0.0.1, 00:15:52, Serial2/0

O        11.0.2.1 [110/65] via 12.0.0.1, 00:15:52, Serial2/0

O        11.0.3.1 [110/65] via 12.0.0.1, 00:15:52, Serial2/0

      12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        12.0.0.0/24 is directly connected, Serial2/0

L        12.0.0.2/32 is directly connected, Serial2/0

      22.0.0.0/8 is variably subnetted, 6 subnets, 2 masks

C        22.0.1.0/24 is directly connected, Loopback1

L        22.0.1.2/32 is directly connected, Loopback1

C        22.0.2.0/24 is directly connected, Loopback2

L        22.0.2.2/32 is directly connected, Loopback2

C        22.0.3.0/24 is directly connected, Loopback3

L        22.0.3.2/32 is directly connected, Loopback3

      23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        23.0.0.0/24 is directly connected, Ethernet0/0

L        23.0.0.2/32 is directly connected, Ethernet0/0

      33.0.0.0/32 is subnetted, 3 subnets

O        33.0.1.3 [110/11] via 23.0.0.3, 00:15:10, Ethernet0/0

O        33.0.2.3 [110/11] via 23.0.0.3, 00:15:10, Ethernet0/0

O        33.0.3.3 [110/11] via 23.0.0.3, 00:15:10, Ethernet0/0

      34.0.0.0/24 is subnetted, 1 subnets

O IA     34.0.0.0 [110/74] via 23.0.0.3, 00:15:10, Ethernet0/0

      44.0.0.0/32 is subnetted, 3 subnets

O IA     44.0.1.4 [110/75] via 23.0.0.3, 00:15:10, Ethernet0/0

O IA     44.0.2.4 [110/75] via 23.0.0.3, 00:15:10, Ethernet0/0

O IA     44.0.3.4 [110/75] via 23.0.0.3, 00:15:10, Ethernet0/0

      100.0.0.0/24 is subnetted, 4 subnets

O E2     100.0.0.0 [110/20] via 12.0.0.1, 00:00:53, Serial2/0

O E2     100.0.1.0 [110/20] via 12.0.0.1, 00:00:58, Serial2/0

O E2     100.0.2.0 [110/20] via 12.0.0.1, 00:00:58, Serial2/0

O E2     100.0.3.0 [110/20] via 12.0.0.1, 00:00:58, Serial2/0

(E2 means External route type 2, in which will not change cost after every hop throughout the OSPF.)

Step 4   Summarize external routes on ASBR router

! (In external route summary is always done on Autonomous System Border Router (ASBR))

R1:

router ospf 1

summary-address 100.0.0.0 255.255.252.0

exit

Task 2:  Verification

• Verify receipt of summary route in neighbor routing table & verify creation of null interface in routing table by following command:

R1#show ip route

Codes: L - local, 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, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

      11.0.0.0/8 is variably subnetted, 6 subnets, 2 masks

C        11.0.1.0/24 is directly connected, Loopback1

L        11.0.1.1/32 is directly connected, Loopback1

C        11.0.2.0/24 is directly connected, Loopback2

L        11.0.2.1/32 is directly connected, Loopback2

C        11.0.3.0/24 is directly connected, Loopback3

L        11.0.3.1/32 is directly connected, Loopback3

      12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        12.0.0.0/24 is directly connected, Serial2/0

L        12.0.0.1/32 is directly connected, Serial2/0

      22.0.0.0/32 is subnetted, 3 subnets

O IA     22.0.1.2 [110/65] via 12.0.0.2, 00:29:15, Serial2/0

O IA     22.0.2.2 [110/65] via 12.0.0.2, 00:29:15, Serial2/0

O IA     22.0.3.2 [110/65] via 12.0.0.2, 00:29:15, Serial2/0

      23.0.0.0/24 is subnetted, 1 subnets

O IA     23.0.0.0 [110/74] via 12.0.0.2, 00:29:15, Serial2/0

      33.0.0.0/32 is subnetted, 3 subnets

O IA     33.0.1.3 [110/75] via 12.0.0.2, 00:28:33, Serial2/0

O IA     33.0.2.3 [110/75] via 12.0.0.2, 00:28:33, Serial2/0

O IA     33.0.3.3 [110/75] via 12.0.0.2, 00:28:33, Serial2/0

      34.0.0.0/24 is subnetted, 1 subnets

O IA     34.0.0.0 [110/138] via 12.0.0.2, 00:28:33, Serial2/0

      44.0.0.0/32 is subnetted, 3 subnets

O IA     44.0.1.4 [110/139] via 12.0.0.2, 00:28:33, Serial2/0

O IA     44.0.2.4 [110/139] via 12.0.0.2, 00:28:33, Serial2/0

O IA     44.0.3.4 [110/139] via 12.0.0.2, 00:28:33, Serial2/0

      100.0.0.0/8 is variably subnetted, 9 subnets, 3 masks

O        100.0.0.0/22 is a summary, 00:00:05, Null0

C        100.0.0.0/24 is directly connected, Loopback100

L        100.0.0.1/32 is directly connected, Loopback100

C        100.0.1.0/24 is directly connected, Loopback101

L        100.0.1.1/32 is directly connected, Loopback101

C        100.0.2.0/24 is directly connected, Loopback102

L        100.0.2.1/32 is directly connected, Loopback102

C        100.0.3.0/24 is directly connected, Loopback103

L        100.0.3.1/32 is directly connected, Loopback103

(When summarization is configured on a router; same router immediately created a routing point to Null 0 for loop prevention.)

R2#show ip route

! (Shows router’s routing table and IPv6 routes entries)

Codes: L - local, 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, H - NHRP, l - LISP

       + - replicated route, % - next hop override

Gateway of last resort is not set

      11.0.0.0/32 is subnetted, 3 subnets

O        11.0.1.1 [110/65] via 12.0.0.1, 00:29:30, Serial2/0

O        11.0.2.1 [110/65] via 12.0.0.1, 00:29:30, Serial2/0

O        11.0.3.1 [110/65] via 12.0.0.1, 00:29:30, Serial2/0

      12.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        12.0.0.0/24 is directly connected, Serial2/0

L        12.0.0.2/32 is directly connected, Serial2/0

      22.0.0.0/8 is variably subnetted, 6 subnets, 2 masks

C        22.0.1.0/24 is directly connected, Loopback1

L        22.0.1.2/32 is directly connected, Loopback1

C        22.0.2.0/24 is directly connected, Loopback2

L        22.0.2.2/32 is directly connected, Loopback2

C        22.0.3.0/24 is directly connected, Loopback3

L        22.0.3.2/32 is directly connected, Loopback3

      23.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        23.0.0.0/24 is directly connected, Ethernet0/0

L        23.0.0.2/32 is directly connected, Ethernet0/0

      33.0.0.0/32 is subnetted, 3 subnets

O        33.0.1.3 [110/11] via 23.0.0.3, 00:28:48, Ethernet0/0

O        33.0.2.3 [110/11] via 23.0.0.3, 00:28:48, Ethernet0/0

O        33.0.3.3 [110/11] via 23.0.0.3, 00:28:48, Ethernet0/0

      34.0.0.0/24 is subnetted, 1 subnets

O IA     34.0.0.0 [110/74] via 23.0.0.3, 00:28:48, Ethernet0/0

      44.0.0.0/32 is subnetted, 3 subnets

O IA     44.0.1.4 [110/75] via 23.0.0.3, 00:28:48, Ethernet0/0

O IA     44.0.2.4 [110/75] via 23.0.0.3, 00:28:48, Ethernet0/0

O IA     44.0.3.4 [110/75] via 23.0.0.3, 00:28:48, Ethernet0/0

      100.0.0.0/22 is subnetted, 1 subnets

O E2     100.0.0.0 [110/20] via 12.0.0.1, 00:00:15, Serial2/0

(Summarized routes are received from external route.)