Question: (a) Give an example where the following algorithm for broadcasting topological update information fails. Initially, all nodes know the correct status of all links. Update rules:
1. When an adjacent link changes status, the node sends the new status in a message on all operating adjacent links.
2. When a node receives a message about a nonadjacent link which differs from its view of the status of the link, it changes the status of the link in its topology table. It also sends the new status in a message on all operating adjacent links except the one on which it received the message.
3. When a node receives a message about an adjacent link which differs from its view of the status of the link, it sends the correct status on the link on which it received the message.
Hint: Failure occurs with simple network topologies, such as the one shown in Fig.
(b) Give an example of failure when the word "except" in rule 2 is changed to "including."
