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.)