# Which network is used for shard replication?

**URL:** <https://discuss.elastic.co/t/which-network-is-used-for-shard-replication/156760>\
**Category:** Elasticsearch\
**Created:** [November 14, 2018, 11:16pm UTC](https://discuss.elastic.co/t/which-network-is-used-for-shard-replication/156760 "2018-11-14T23:16:04Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![YuWatanabe](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/yuwatanabe/32/13259_2.png) [@YuWatanabe](https://discuss.elastic.co/u/YuWatanabe)\
**Post date:** [November 14, 2018, 11:16pm UTC](https://discuss.elastic.co/t/which-network-is-used-for-shard-replication/156760/1 "2018-11-14T23:16:04Z")

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Hello.

I am diagnosing the reason for bulk rejects which I am seeing in my environment.

I read below article and document understand the mechanism of replication.

1. [https://www.elastic.co/blog/why-am-i-seeing-bulk-rejections-in-my-elasticsearch-cluster](https://www.elastic.co/blog/why-am-i-seeing-bulk-rejections-in-my-elasticsearch-cluster)

2. [https://www.elastic.co/guide/en/elasticsearch/guide/2.x/distrib-write.html](https://www.elastic.co/guide/en/elasticsearch/guide/2.x/distrib-write.html)

What I would like to ask is after _write_ to primary succeeds how are _write_ requests is sent to the other node? Does it use _bulk request_ again , or does it use internal communication ( Transport protocol ) ?

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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:** [November 15, 2018, 8:29am UTC](https://discuss.elastic.co/t/which-network-is-used-for-shard-replication/156760/2 "2018-11-15T08:29:42Z")

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All node-to-node communication in a cluster uses the transport protocol (as opposed to HTTP, which is only used for client-to-node communication).

> [@YuWatanabe](#):
>
> What I would like to ask is after _write_ to primary succeeds how does _write_ request is sent to the other node?

Perhaps a minor point, but note that a write to the primary doesn't succeed until after it's been replicated successfully to every replica.

> [@YuWatanabe](#):
>
> Does it use _bulk request_ again

Yes, they are bulk requests, in the sense that a single primary-to-replica request may contain many indexing operations.

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<div class="post-metadata">

**Author:** ![YuWatanabe](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/yuwatanabe/32/13259_2.png) [@YuWatanabe](https://discuss.elastic.co/u/YuWatanabe)\
**Post date:** [November 16, 2018, 5:20am UTC](https://discuss.elastic.co/t/which-network-is-used-for-shard-replication/156760/3 "2018-11-16T05:20:53Z")

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Thank you for the reply.

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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:** [December 14, 2018, 5:20am UTC](https://discuss.elastic.co/t/which-network-is-used-for-shard-replication/156760/4 "2018-12-14T05:20:56Z")

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Closed on December 14, 2018, 5:20am UTC

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