EIGRP Query Propagation within Ring Topology

[Ziyang Wang]

Hi All,

I have a question about EIGRP query propagation within ring topology.

For example the following ring topology, here are 5 routers, all the links has the same metric, if the link between A and C down, A will send query to B, B ask E, then will E ask D or not ?

In my understanding E can reply directly, as it has a FS in topology, i.e., E-D-C. But I saw some docs said E will keep querying D, so I am confused.

       A--------B--------E

       |                                |

       |                                |

       C-----------------D

[pieterh]

>>>  if the link between A and B down, A will send query to B, B ask E, then will E ask D or not ? <<<

there is something wrong in this question.

if link between A and B is down, A is not able to  send query to B ????

[Georg Pauwen]

Hello,

E needs to query B and D regardless of it having a feasible successor, since E (and any other EIGRP router in your topology) only knows the topology up (and not beyond) its directly connected neighbors.

Which basically means, when there is a topology change, queries are ALWAYS sent.

Have a look at the document below, which describes the process very detailed.

Understanding EIGRP Queries

https://packetlife.net/blog/2010/mar/22/understanding-eigrp-queries/

[balaji.bandi]

This is based on the election process of EIGRP neighbour process, when the link mentioned in the post go down, there is only option available for you is one Path only.