# Mqtt in and out topic
**URL:** https://discourse.nodered.org/t/mqtt-in-and-out-topic/83565
**Category:** General
**Created:** [10 December 2023 02:03 UTC](https://discourse.nodered.org/t/mqtt-in-and-out-topic/83565 "2023-12-10T02:03:30Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@mohammad-torabi-84](https://discourse.nodered.org/u/mohammad-torabi-84)
#### Post date: [10 December 2023 02:03 UTC](https://discourse.nodered.org/t/mqtt-in-and-out-topic/83565/1 "2023-12-10T02:03:31Z")
Hi,
I have a very simple flow that contains an mqtt-in node, two mqtt-out nodes and two function nodes.
the topic of the mqtt-in node is home/Garage/# and the topic of mqtt-out nodes are home/Garage/door/status and home/Garage/door/command.
obviously this simple flow has an issue which causes an infinite loop.
how can I fix the issue?
Thanks,
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### Author:  [@jbudd](https://discourse.nodered.org/u/jbudd)
#### Post date: [10 December 2023 02:14 UTC](https://discourse.nodered.org/t/mqtt-in-and-out-topic/83565/2 "2023-12-10T02:14:06Z")
Hello @mohammad-torabi-84
Either subscribe to `home/garage/+/status`
Or (probably better) use `command/home/garage/door` and `status/home/garage/door`
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### Author:  [@mohammad-torabi-84](https://discourse.nodered.org/u/mohammad-torabi-84)
#### Post date: [10 December 2023 02:33 UTC](https://discourse.nodered.org/t/mqtt-in-and-out-topic/83565/3 "2023-12-10T02:33:46Z")
So, these two topic of command/home/garage/door and status/home/garage/door have the same result. because the mqtt-out node has the same topic of the mqtt-in node. this will cause an infinite loop in the flow.
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### Author:  [@jbudd](https://discourse.nodered.org/u/jbudd)
#### Post date: [10 December 2023 07:26 UTC](https://discourse.nodered.org/t/mqtt-in-and-out-topic/83565/4 "2023-12-10T07:26:06Z")
I misinterpreted your question.
1. Presumably the messages that your flow sends on home/garage/door/command are instructions to the door -"Open", "Close" etc. ?
2. Why does your flow send messages on home/garage/door/status?
What device subscribes to these messages?
I assumed that these messages would be sent by the door to indicate it's current state - "Opened", "Closed" etc.
3. What device publishes the message that your mqtt-in node is intended to receive?
Do you have control over the topic this device uses?
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### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [10 December 2023 07:35 UTC](https://discourse.nodered.org/t/mqtt-in-and-out-topic/83565/5 "2023-12-10T07:35:22Z")
Add a Filter node in front of each mqtt out node. That should break the loop.
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### Author:  [@dynamicdave](https://discourse.nodered.org/u/dynamicdave)
#### Post date: [10 December 2023 07:37 UTC](https://discourse.nodered.org/t/mqtt-in-and-out-topic/83565/6 "2023-12-10T07:37:13Z")
Your MQTT-In node is subscribing to the topic `home/Garage/#`
The hash ` #` symbol is a wildcard which means the node will accept anything from that point onwards.
Your MQTT-Out nodes are publishing to the topic `home/Garage/door/status` and
`home/Garage/door/command`
If you write the topics out as a list you can see the overlap.
`home/Garage/#`
`home/Garage/door/status`
`home/Garage/door/command`
So your **MQTT-In** will react everytime you **send** a message. An infinite loop has been created.
As @jbudd said you need to adjust the topic names or as @Colin says add a 'Filter'node.
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### Author:  [@Colin](https://discourse.nodered.org/u/Colin)
#### Post date: [10 December 2023 08:06 UTC](https://discourse.nodered.org/t/mqtt-in-and-out-topic/83565/7 "2023-12-10T08:06:36Z")
If you tell us what is in the function nodes, and why, there may be a better way of handling the problem.
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### Author:  [@system](https://discourse.nodered.org/u/system)
#### Post date: [24 December 2023 08:06 UTC](https://discourse.nodered.org/t/mqtt-in-and-out-topic/83565/8 "2023-12-24T08:06:51Z")
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