Summarization challenge

This exercise was first post by Arwin Reprakash (http://ithitman.blogspot.com/2015/03/configuring-ospf-summarization-lab.html#more). I took his post and modify it to create a new requirement

 

Startup configuration (VIRL)

Final configuration (VIRL)

THE PROBLEM

Summarize 192.168.1.2/32 from Area 2 as 192.168.1.0/24 into area 0. You have no Access to R1


RESTRICCIONS

* You only have Access to routers R2 and R3
* Do not use area-range command or summary-address to summarize the routes into Area 0.
* R3 and other routers in Area 0 or any new additional areas should only have the summary address to reach 192.168.1.2.
* If prefix 192.168.1.2/32 is withdrawn (i.e shutdown loopback0 on R2) from R1 OSPF database then 192.168.1.0/24 should not be summarized/advertised into area 0.


THE SOLUTION

When you run the lab you will notice that all the routers know how to reach each other by ospf. That's is good cause now we could créate a BGP relationship between R2 and R3 bypassing R1, and then advertise a summary address for R3

This is the configuration in R2 to summarize and advertise 192.168.1.0 (summary-only)

R2#show run | section bgp
router bgp 1
 bgp log-neighbor-changes
 network 192.168.1.2 mask 255.255.255.255
 aggregate-address 192.168.1.0 255.255.255.0 summary-only
 neighbor 13.13.13.3 remote-as 1

This is the configuration in R3

R3#show run | section bgp
router bgp 1
 bgp log-neighbor-changes
 neighbor 12.12.12.2 remote-as 1


Finally let's check the routing table in R3

R3#show ip route bgp
B     192.168.1.0/24 [200/0] via 12.12.12.2, 00:08:21


Ok it work,
When l0 in R2 is down, the route will  disappear from R3 routing table




I use cisco virl for these labs but i think they will work ok in GNS3 too.
Please leave your feedback