The stub router will depend on itsneigboring router to send the proper updates to all peers.Ī router can be configured as stub using the following command: Any neighbor that receives a packet informing it of the stub status will not query the stub router for any routes, and a router that has a stub peer will not query that peer. To prevent such situations Cisco introduced stub routing in EIGRP. SIA situations can become very ugly and cause some serious downtime. Since a response was not received the EIGRP neighborship will be torn down in some time and re-established using normal procedure.
On RouterB the route to 10.1.1.0/24 is now said to be Stuck in Active (SIA).
So RouterD does not respond to RouterC which does not respond to RouterB. Now let’s assume that RouterE has temporary network lag or high CPU usage and fails to respond to RouterD. So all the Routers in the chain are queried. Meanwhile RouterD will query RouterE and wait for RouterE to respond. RouterC will query RouterD and wait for RouterD to resond before it will respond to RouterB. At this stage the route to 10.1.1.0/24 is said to have gone active. If RouterA goes down, RouterB will query RouterC for any an alternate route to 10.1.1.0/24.
Let’s assume that EIGRP is running on all routers in Figure 1 and RouterA is advertising a route to 10.1.1.0/24 network to RouterB. Lets look at Figure 1 to understand what happens when a route is lost : The neighbors in turn will query their neighbor and will not respond to the original query till it receives a reply from all its neighbors. If a route is lost, it will query every neighbor for that route. EIGRP keeps track of all the routes that it learns.
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