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Problem 3.6.1 (Bi-directional links). OSPF insists that all links which are used in any forwarding path are bi-directional. In contrast, this was not ensured in the first version of the RIP routing protocol (RIPv1). Find an example of a RIPv1 network where something goes wrong when a link is only uni-directional.

Problem 3.6.1 (Bi-directional links). OSPF insists that all links which are used in any forwarding path are bi-directional. In contrast, this was not ensured in the first version of the RIP routing protocol (RIPv1). Find an example of a RIPv1 network where something goes wrong when a link is only uni-directional.

Database System Concepts
Database System Concepts
7th Edition
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Chapter1: Introduction
Section: Chapter Questions
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Can someone please help me with problem 3.6.1? I'll give a thumb up to thank for your time.
As I'm reviewing for my upcoming exam, I really need an answer from an expert in the field. 
Please do not send me an answer from chatGPT. I've got enough of that, so please be helpful. Thank you.

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This question is about the Hello Protocol in OSPF

A router X starts sending Hello packets after it has been switched on. At that time it has not yet established any adjacency and the Neighbor list will be empty. Another router Y receiving a Hello packet: • Checks whether all his own pre-configured parameter values for Area-ID, NetworkMask, Authentication, HelloInterval, Router DeadInterval, and Options are the same as in the received packet. • If not, the packet is dropped. Otherwise, y establishes an adjacency with X, and Y includes the router id of X in the neighbor list of its subsequent Hello packets. • When X receives a Hello packet from Y with X's router id in the Neighbor list and an agreeable set of configuration/authentication data, then X knows that the link is bi-directional and also establishes an adjacency to Y. In general, only bi-directional links are considered in routing calculations. If any router finds that one particular link is only reported by one of the involved routers and not the other (in their respective router LSAs), it will not be used. After router X has established an adjacency with router Y, it expects to receive Hello packets from Y peri- odically (and vice versa). If X receives no Hello packet for a time of at least Router-Dead-Interval (typical default value is 40 seconds), then X concludes that neighbour Y is dead and will issue a (triggered) router LSA in which the router link to Y is not listed anymore. It will furthermore re-calculate its routes to ensure that Y is not used as a next-hop anymore. Problem 3.6.1 (Bi-directional links). OSPF insists that all links which are used in any forwarding path are bi-directional. In contrast, this was not ensured in the first version of the RIP routing protocol (RIPv1). Find an example of a RIPv1 network where something goes wrong when a link is only uni-directional.
Transcribed Image Text:A router X starts sending Hello packets after it has been switched on. At that time it has not yet established any adjacency and the Neighbor list will be empty. Another router Y receiving a Hello packet: • Checks whether all his own pre-configured parameter values for Area-ID, NetworkMask, Authentication, HelloInterval, Router DeadInterval, and Options are the same as in the received packet. • If not, the packet is dropped. Otherwise, y establishes an adjacency with X, and Y includes the router id of X in the neighbor list of its subsequent Hello packets. • When X receives a Hello packet from Y with X's router id in the Neighbor list and an agreeable set of configuration/authentication data, then X knows that the link is bi-directional and also establishes an adjacency to Y. In general, only bi-directional links are considered in routing calculations. If any router finds that one particular link is only reported by one of the involved routers and not the other (in their respective router LSAs), it will not be used. After router X has established an adjacency with router Y, it expects to receive Hello packets from Y peri- odically (and vice versa). If X receives no Hello packet for a time of at least Router-Dead-Interval (typical default value is 40 seconds), then X concludes that neighbour Y is dead and will issue a (triggered) router LSA in which the router link to Y is not listed anymore. It will furthermore re-calculate its routes to ensure that Y is not used as a next-hop anymore. Problem 3.6.1 (Bi-directional links). OSPF insists that all links which are used in any forwarding path are bi-directional. In contrast, this was not ensured in the first version of the RIP routing protocol (RIPv1). Find an example of a RIPv1 network where something goes wrong when a link is only uni-directional.
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