It seems that you have provided the answer to your own question. With OSPF as with some other protocols when you configure a summary address the IOS creates a route for the summary address pointed at null0. The purpose for this is to prevent looping as you have said.
If we look more closely at the logic it is like this: you will be advertising the summary route to your neighbors, for example 18.104.22.168/24 which tells your neighbors that if they need to get to that network that they should forward to you and you can get to the destination. Lets assume that your router has learned these subnets from its OSPF neighbors 22.214.171.124/26, 126.96.36.199/26, and 188.8.131.52/26 but it does not have a route to 184.108.40.206/26 (which includes the 220.127.116.11 address). If a neighbor forwards to your router a packet with destination 18.104.22.168 what should you do? Lets also assume that you have learned your default route from that neighbor. If you forward toward your default route it would be forwarding back to the neighbor who sent you the packet and a loop is created. So OSPF creates the null0 route so that if you do not know how to forward to the destination address you will discard the packet.
Hi everyone, I would like to thank you in advance for any help you can provide a newcomer like myself!
Im studying the 100-105 book by Odom and am currently on the topic of Port security. I purchased a used 2960 and I'm trying to follow a...
While deploying a number of 18xx/2802/3802 model access points (APs), which run AP-COS as their operating platform. It can be observed on some occasions that while many of their access points were able to join the fabric WLC withou...
I am going to design and build an LAN network under a tunnel underground with long distance between the switches.
I will have 2 Catalyst switches and 8 Industrial IE3000, and they will be connected with fiber.
For now I am planning on use Layer-2 s...