# EIGRP Queries and Stuck in Active
**URL:** https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914
**Category:** Lessons Discussion
**Created:** [December 22, 2016, 12:57am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914 "2016-12-22T00:57:10Z")
**Posts on this page:** 20
**Page:** 3
### Author:  [@shantel](https://forum.networklessons.com/u/shantel)
#### Post date: [December 22, 2016, 12:57am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/41 "2016-12-22T00:57:39Z")
19 posts were merged into an existing topic: [EIGRP Queries and Stuck in Active](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914)
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### Author:  [@chrisnewnham17](https://forum.networklessons.com/u/chrisnewnham17)
#### Post date: [September 14, 2017, 1:01pm UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/42 "2017-09-14T13:01:29Z")
If a route/neighbour fails, how can you recover from SIA? Recycle the interface facing the neighbour that’s down?
I’m also curious how you can simulate this in GNS3. Surely the main cause of SIA is congestion? How did you replicate the replys from R2 not reaching R1? Use an ACL?
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### Author:  [@lagapidis](https://forum.networklessons.com/u/lagapidis)
#### Post date: [September 15, 2017, 5:44am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/43 "2017-09-15T05:44:40Z")
Hello Chris
> [@chrisnewnham17](#):
>
> If a route/neighbour fails, how can you recover from SIA?
If a route or neighbour fails, and there is no feasible successor, an EIGRP enabled router will go from Passive to Active. This is normal behaviour. This is also the expected behaviour because it must attempt to find a new route to the destination. This does not mean that the router goes into SIA.
The router will only go into SIA if several things go wrong on the network as described in the lesson.
Now if you do end up in SIA, there is no “quick fix” solution like the bouncing of an interface. You must look more deeply into the problem. What is the reason for SIA? It is usually due to congestion on the network, a malfunctioning link or a unidirectional link.
Another reason may be the use of an IOS before 12.1 that doesn’t use the SIA query and reply packets (which reduce the probability of an SIA situation).
Another way to resolve SIA problems is to configure EIGRP summarization and/or the EIGRP stub feature. All of these must be implemented using proper troubleshooting procedures to evaluate the results of each change.
> [@chrisnewnham17](#):
>
> I’m also curious how you can simulate this in GNS3. Surely the main cause of SIA is congestion? How did you replicate the replys from R2 not reaching R1? Use an ACL?
To simulate lost EIGRP packets in GNS3 you can use a traffic generator to create network congestion. There are several options for this, [one of which you can find here](https://supportforums.cisco.com/t5/network-infrastructure-documents/easy-traffic-generator-works-with-gns3/ta-p/3160775). You can make your interfaces 10Mbps if they are Ethernet or you can create serial links and modify the data rate accordingly to make the data congestion reach 100% of bandwidth. When you do this however, make sure that you configure the `ip bandwidth-percent eigrp` command on the interface in question at a very low percentage such as 1 or 2 percent. This should have the result of losing some EIGRP packets.
Try it out and let us know your results!
I hope this has been helpful!
Laz
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### Author:  [@hengsovandara1345](https://forum.networklessons.com/u/hengsovandara1345)
#### Post date: [December 28, 2017, 10:07am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/44 "2017-12-28T10:07:43Z")
Hello
Is this feature enable by default in EIGRP?
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### Author:  [@ReneMolenaar](https://forum.networklessons.com/u/ReneMolenaar)
#### Post date: [January 2, 2018, 12:16pm UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/45 "2018-01-02T12:16:11Z")
Yes it is 🙂
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### Author:  [@vinod.kr.agrahari](https://forum.networklessons.com/u/vinod.kr.agrahari)
#### Post date: [September 1, 2018, 8:24am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/46 "2018-09-01T08:24:02Z")
Thanks for such a good brief .Can we have a lab where we can test it.
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### Author:  [@knaik99](https://forum.networklessons.com/u/knaik99)
#### Post date: [March 24, 2019, 3:05pm UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/47 "2019-03-24T15:05:49Z")
as Router send SIA query to router after 1.5 Second but as link is of fiber and there is unidirectional link failure then SIA query of neighbor router will not reach towards query sender (i.e. Router)
then what will happen?
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### Author:  [@lagapidis](https://forum.networklessons.com/u/lagapidis)
#### Post date: [March 26, 2019, 4:34pm UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/48 "2019-03-26T16:34:32Z")
Hello Kunal
SIA queries and replies are used in order to minimize situations where neighbor adjacencies that are a result of lost replies to regular EIGRP queries. These lost replies are usually due to **intermittent** problems that may prevent **some** replies from reaching their destinations, such as high CPU, flapping links, network congestion etc. If you have a situation where there is a **permanent** unidirectional link failure, SIA will not resolve this issue. The SIA response will never reach the sender.
Take a look at the lesson below that further describes the EIGRP Queries and SIA:
> **[EIGRP Queries and Stuck in Active](https://networklessons.com/eigrp/eigrp-queries-and-stuck-in-active)**
>
> EIGRP uses a query process when it loses routes. We'll take a look at this query process and also what SIA (Stuck In Active) is and how to deal with it.
I hope this has been helpful!
Laz
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### Author:  [@jallen314](https://forum.networklessons.com/u/jallen314)
#### Post date: [November 21, 2019, 12:24am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/49 "2019-11-21T00:24:42Z")
I am probably missing something, but wouldn’t a router already know about every possible route to a destination? I guess a router could know about a route and not be advertising it for some reason?
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### Author:  [@lagapidis](https://forum.networklessons.com/u/lagapidis)
#### Post date: [November 22, 2019, 6:26am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/50 "2019-11-22T06:26:52Z")
Hello Justin
I’m not quite sure to what your statement is referring, but just to clarify, EIGRP is the method by which routers learn about every possible route to the destination. If the routing protocol mechanism fails, then the learning of the routes also fails.
If this does not address your question fully, please clarify.
I hope this has been helpful!
Laz
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### Author:  [@narad](https://forum.networklessons.com/u/narad)
#### Post date: [July 2, 2021, 11:18am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/51 "2021-07-02T11:18:18Z")
Who Actually start the Query Timer, The original initiator or every router manage and count their timer itself.??
Once the route will get stuck in SIA then how that route will be removed from topology table ??
lets a route fails , and after how many sec the router will generate the query ??, because by default till 15 sec (hold time )the route will be there in topology table , so after hold down time expire it will generate the query or all of sudden it will generate the query ?.if all of sudden it sends the query then how it detects the failure ,is it because of incremental update ??
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### Author:  [@lagapidis](https://forum.networklessons.com/u/lagapidis)
#### Post date: [July 11, 2021, 5:19am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/52 "2021-07-11T05:19:59Z")
Hello Narad
> [@narad](#):
>
> Who Actually start the Query Timer, The original initiator or every router manage and count their timer itself.??
Take a look at this post:
> [@EIGRP Queries and Stuck in Active](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/28):
>
> Hi Paul, You generally have it right. The short answer is after 90 seconds, an SIA-Query is sent. The longer answer: Each router manages its own SIA Query and SIA Query Response management. This means that as soon as each router has put a route in Active (regardless of whether the router in question was the actual first router to start the process) and has sent a Query to its neighbors, that router also starts a timer. At 90 seconds, for each neighbor from which it has not received a reply…
> [@narad](#):
>
> Once the route will get stuck in SIA then how that route will be removed from topology table ??
This happens by definition. If a route is stuck in active, the neighbor adjacency will be dropped. When you drop a neighbor adjacency, you essentially lose all routes you learned via that neighbor.
> [@narad](#):
>
> lets a route fails , and after how many sec the router will generate the query ??
The hello and hold-down timers are used to maintain neighbor adjacencies, and these use different values. The SIA timer is used not only to resolve EIGRP failure but also to deal with the propagation delay of learning EIGRP routes in a large topology. Take a look at the following post for more information:
> [@EIGRP Queries and Stuck in Active](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/32):
>
> Hello Pradeep. These are very good questions. In the first question, the answer is yes, even if hello packets are being recieved from a router, the SIA state will still kill the neighbour adjacency. You can think of the Stuck in Active condition as an additional condition for which neighbour adjacencies are killed. As for your second question, yes you’re right, the SIA reply may also fail to reach Router 1 due to congestion. Only one SIA Query is sent at 90 seconds. However, the purpose of…
I hope this has been helpful!
Laz
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### Author:  [@narad](https://forum.networklessons.com/u/narad)
#### Post date: [July 11, 2021, 7:04pm UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/53 "2021-07-11T19:04:29Z")
What i understand is that ..
if within 180 sec the router will get the Query reply of the loosing route and even teh neighbor says that we dont know that route then the neighborship will not be broken ..But if the neighbor router will not respond the query within 3 min then the router will be called as SIA state and then the neighborship will be resetted ..
so conclusively , most often in production the router gets the reply bcz its a huge time as 3min ..
kindly correct me , if a neighbor router does not know about the loosing route and neighbor router replied to our query saying i don’t have any alternate path to this loosing route then the neghborship will not be broken ..right..!!!
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### Author:  [@lagapidis](https://forum.networklessons.com/u/lagapidis)
#### Post date: [August 21, 2021, 4:27am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/54 "2021-08-21T04:27:14Z")
Hello Narad
> [@narad](#):
>
> so conclusively , most often in production the router gets the reply bcz its a huge time as 3min …
Under normal circumstances, a query will be responded to and there will be no loss of EIGRP neighbors. The value of 3 minutes is more than enough time for the EIGRP queries to reach the farthest EIGRP routers on the network and to get a response. But the primary problem is not simply due to a large network, but due to lost query replies. Remember, on a large network, many things can go wrong, including congestion, corruption of packets, and link failures. Query responses are not resent if they don’t reach their destination, so any lost query response will result in a stuck in active.
> [@narad](#):
>
> kindly correct me , if a neighbor router does not know about the loosing route and neighbor router replied to our query saying i don’t have any alternate path to this loosing route then the neghborship will not be broken …right…!!!
If a query response is successfully received for all queries that a router sends out when a link fails, then yes, the neighbor adjacency will not be torn down.
I hope this has been helpful!
Laz
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### Author:  [@wilder7bc](https://forum.networklessons.com/u/wilder7bc)
#### Post date: [September 13, 2021, 3:06am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/55 "2021-09-13T03:06:04Z")
woot finally made it past the EIGRP stuff for my initial read and study anyway. Great lesson!
On to OSPF!
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### Author:  [@lagapidis](https://forum.networklessons.com/u/lagapidis)
#### Post date: [September 18, 2021, 5:09am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/56 "2021-09-18T05:09:16Z")
Hi Brian
Good job! Keep the momentum going, and we’ll be here to answer any questions you have!
Laz
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### Author:  [@funda.kaplan](https://forum.networklessons.com/u/funda.kaplan)
#### Post date: [June 6, 2023, 4:23am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/57 "2023-06-06T04:23:04Z")
Hi,
Doesn’t eigrp send hello messages periodically? Shouldn’t it consider the hello messages and not drop the neighborhood even if there is no query response?
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### Author:  [@lagapidis](https://forum.networklessons.com/u/lagapidis)
#### Post date: [June 7, 2023, 5:37am UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/58 "2023-06-07T05:37:50Z")
Hello Funda
Yes, EIGRP routers do send hello messages periodically. However, the reason for dropping the neighbor adjacency in this case is not because the neighbors lost connectivity or because of a lack of hellos, but because, through the process described in the lesson, the R1 router was put into a Stuck in Active (SIA) state. When this happens, the adjacency is dropped. That’s simply how EIGRP is designed.
The purpose of dropping the adjacency is to remove all the routes learned from that neighbor from the local router to get out of the SIA state. Once this is done, relearning the routes begins from scratch.
To help improve the operation of EIGRP and reduce the number of dropped adjacencies, Cisco introduced the use of SIA query and SIA reply, as described in the lesson.
I hope this has been helpful!
Laz
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### Author:  [@funda.kaplan](https://forum.networklessons.com/u/funda.kaplan)
#### Post date: [June 14, 2023, 1:42pm UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/59 "2023-06-14T13:42:31Z")
Thanks Lazaros, its been helpful
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### Author:  [@thschaff](https://forum.networklessons.com/u/thschaff)
#### Post date: [February 27, 2024, 4:00pm UTC](https://forum.networklessons.com/t/eigrp-queries-and-stuck-in-active/914/60 "2024-02-27T16:00:36Z")
I would like to add the following information for reference. Let’s say R1 queries R2 for a missing router. **R2 will only query its neighbors if it previously knew about the requested route.**
This is very important, because it doesn’t do so if e.g. R2 received a summary route from R1 and R1 queries for a specific route contained in this summary route. This gets important when we talk about EIRP traffic engineering etc.
I hope this helps.
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