# Master node network bandwidth requirements

**URL:** <https://discuss.elastic.co/t/master-node-network-bandwidth-requirements/330468>\
**Category:** Elasticsearch\
**Created:** [April 20, 2023, 6:36pm UTC](https://discuss.elastic.co/t/master-node-network-bandwidth-requirements/330468 "2023-04-20T18:36:29Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Aurel1](https://avatars.discourse-cdn.com/v4/letter/a/90db22/32.png) [@Aurel1](https://discuss.elastic.co/u/Aurel1)\
**Post date:** [April 20, 2023, 6:36pm UTC](https://discuss.elastic.co/t/master-node-network-bandwidth-requirements/330468/1 "2023-04-20T18:36:29Z")

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Hello, I have a cluster with dedicated master nodes. I recently noticed, that the current master has relatively high network bandwidth requirements (sustained non-stop ~15Mb/s in, and ~15Mb/s out). It seems that the traffic between the master node and the individual data nodes is proportional to the number of indices/segments on the respective data node. Is there any info/guide regarding the network requirements of master-only nodes and how to optimize it?

Also, as a bonus, I noticed a long-term pattern, where the traffic goes rapidly down (around 50%) every 3-4 days and then slowly climbs back up to the ~15Mb/s over the course of 24 hours, stays there for ~3 days and falls back to 50% as the next "iteration" starts. Any idea what could be the reason? The number of indices is only growing, we do not delete large amounts of data with that period.

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**Author:** ![DavidTurner](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/davidturner/32/22453_2.png) [@DavidTurner](https://discuss.elastic.co/u/DavidTurner)\
**Post date:** [April 20, 2023, 7:22pm UTC](https://discuss.elastic.co/t/master-node-network-bandwidth-requirements/330468/2 "2023-04-20T19:22:57Z")

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That traffic pattern doesn't match anything master-related of which I'm aware. Possibly `GET _tasks?detailed` will give some clues about what it's doing. If not, there's some more detailed network stats coming in 8.8.0 which will answer this for sure:

> <https://github.com/elastic/elasticsearch/pull/94543>
>
> Adds to the transport stats a histogram of transport message sizes for each tran…sport action.
> 
> Closes https://github.com/elastic/elasticsearch/issues/88151

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**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [May 18, 2023, 7:22pm UTC](https://discuss.elastic.co/t/master-node-network-bandwidth-requirements/330468/3 "2023-05-18T19:22:59Z")

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