Auto summarization 

Task 1 :- Configure IP Address according topology

Task 2 :- Conifgure loopback Address

Task 3 :- Configure  RIP

Task 4 :- Make sure  IOU1(R1) are on Auto summarization 

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Task 1 :- Configure IP Address according topology


Router IOU1 configuration...
 
IOU1#
IOU1#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
IOU1(config)#
IOU1(config)#interface ethernet 0/0
IOU1(config-if)#
IOU1(config-if)#ip address 192.168.12.1 255.255.255.0
IOU1(config-if)#
IOU1(config-if)#no shutdown
IOU1(config-if)#exit
IOU1(config)#

Router IOU2 configuration...

IOU2#
IOU2#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
IOU2(config)#
IOU2(config)#interface ethernet 0/0
IOU2(config-if)#
IOU2(config-if)#ip address 192.168.12.2 255.255.255.0
IOU2(config-if)#
IOU2(config-if)#no shutdown
IOU2(config-if)#exit
IOU2(config)#

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 Task 2 :- Conifgure loopback Address


Router IOU1 configuration...

IOU1(config)#
IOU1(config)#interface loopback 1
IOU1(config-if)#ip address 10.1.1.1 255.255.255.0
IOU1(config-if)#exit
IOU1(config)#interface loopback 2            
IOU1(config-if)#
IOU1(config-if)#ip address 10.1.2.1 255.255.255.0
IOU1(config-if)#exit
IOU1(config)#interface loopback 3            
IOU1(config-if)#
IOU1(config-if)#ip address 10.1.3.1 255.255.255.0
IOU1(config-if)#exit
IOU1(config)#interface loopback 4            
IOU1(config-if)#
IOU1(config-if)#ip address 10.1.4.1 255.255.255.0
IOU1(config-if)#exit
IOU1(config)#interface loopback 5            
IOU1(config-if)#
IOU1(config-if)#ip address 10.1.5.1 255.255.255.0
IOU1(config-if)#exit
IOU1(config)# 

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Task 3 :- Configure  RIP

Router IOU1 configuration...

IOU1(config)#
IOU1(config)#router rip
IOU1(config-router)#network 192.168.12.0
IOU1(config-router)#network 10.1.1.0
IOU1(config-router)#network 10.1.2.0
IOU1(config-router)#network 10.1.3.0
IOU1(config-router)#network 10.1.4.0
IOU1(config-router)#network 10.1.5.0
IOU1(config-router)#
IOU1(config-router)#version 2
IOU1(config-router)#

!! here We can see there in no any no auto summary command we are doing Auto summarization !!

Router IOU2 configuration...

IOU2(config)#
IOU2(config)#router rip
IOU2(config-router)#network 192.168.12.0
IOU2(config-router)#
IOU2(config-router)#version 2
IOU2(config-router)# 
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Task 4 :- Make sure  IOU1(R1) are on Auto summarization 


IOU2#show ip route rip
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

R     10.0.0.0/8[120/1] via 192.168.12.1, 00:00:18, Ethernet0/0
IOU2#
!! Routing table route is 10.0.0./8 but we adverstise on 10.1.1.0/24 here they performer by default Auto summarization !!

When we use " no auto summary command " 

IOU1(config)#router rip
IOU1(config-router)#no auto-summary
IOU1(config-router)#

let's look


IOU2#show ip route rip
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

      10.0.0.0/24 is subnetted, 5 subnets
R        10.1.1.0 [120/1] via 192.168.12.1, 00:00:05, Ethernet0/0
R        10.1.2.0 [120/1] via 192.168.12.1, 00:00:05, Ethernet0/0
R        10.1.3.0 [120/1] via 192.168.12.1, 00:00:05, Ethernet0/0
R        10.1.4.0 [120/1] via 192.168.12.1, 00:00:05, Ethernet0/0
R        10.1.5.0 [120/1] via 192.168.12.1, 00:00:05, Ethernet0/0
IOU2#


every route are coming individual 

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manual summarization

Q :- how to find manual summarization 


we have....

10.1.1.0
10.1.2.0
10.1.3.0
10.1.4.0
10.1.5.0

let's take first and last subnets

10.1.1.0
10.1.5.0

10.1
10.1 are both same means  2 octet's same

8 bit each octat's

8+8 = 16

now binary of

1 = 00000001
5 = 00000101

here we have 5 bit match

16 + 5 = 21

10.1.0.0/21 this our summarize route

assign summarize route on Router


Router IOU1 Configuration ....

IOU1(config)#
IOU1(config)#interface ethernet 0/0
IOU1(config-if)#
IOU1(config-if)#ip summary-address rip 10.1.0.0 255.255.248.0   !! this is the subnetmask of /21 !!
IOU1(config-if)#
 
let's check .,,
 
IOU2#show ip route rip
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

      10.0.0.0/21 is subnetted, 1 subnets
R        10.1.0.0 [120/1] via 192.168.12.1, 00:00:13, Ethernet0/0
IOU2#


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