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# Overview of Multi-site Caching

A multi-site installation consists of two or more distributed systems that are loosely coupled. Each site manages its own distributed system, but region data is distributed to remote sites using one or more logical connections.

The logical connections consist of a gateway sender in the sending site, and a gateway receiver in the receiving site. In a client/server installation, gateway senders and gateway receivers are configured in the server layer.

Gateway senders and receivers are defined at startup in the distributed system member caches. A site can use *serial* and/or *parallel* gateway sender configurations, as described in [Gateway Senders](multisite_overview.html#topic_9AA37B43642D4DE19072CA3367C849BA).

<img src="../../images/consistent_multisite.png" id="topic_70045702D3994BC692E75102CE01BD7C__image_BCD6320F34A645A7911AA25EDEA6D971" class="image" />

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## Consistency for WAN Updates

<span class="keyword">Geode</span> ensures that all copies of a region eventually reach a consistent state on all members and clients that host the region, including <span class="keyword">Geode</span> members that distribute region events across a WAN.

By default, potential WAN conflicts are resolved using a timestamp mechanism. You can optionally install a custom conflict resolver to apply custom logic when determining whether to apply a potentially conflicting update received over a WAN.
<commit_msg>Topologies section: fix header/title format<commit_after>---
title: Overview of Multi-site Caching
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<a id="topic_70045702D3994BC692E75102CE01BD7C"></a>


A multi-site installation consists of two or more distributed systems that are loosely coupled. Each site manages its own distributed system, but region data is distributed to remote sites using one or more logical connections.

The logical connections consist of a gateway sender in the sending site, and a gateway receiver in the receiving site. In a client/server installation, gateway senders and gateway receivers are configured in the server layer.

Gateway senders and receivers are defined at startup in the distributed system member caches. A site can use *serial* and/or *parallel* gateway sender configurations, as described in [Gateway Senders](multisite_overview.html#topic_9AA37B43642D4DE19072CA3367C849BA).

<img src="../../images/consistent_multisite.png" id="topic_70045702D3994BC692E75102CE01BD7C__image_BCD6320F34A645A7911AA25EDEA6D971" class="image" />

<a id="topic_C74A0961937640B199396DC925D8D782"></a>

## Consistency for WAN Updates

<span class="keyword">Geode</span> ensures that all copies of a region eventually reach a consistent state on all members and clients that host the region, including <span class="keyword">Geode</span> members that distribute region events across a WAN.

By default, potential WAN conflicts are resolved using a timestamp mechanism. You can optionally install a custom conflict resolver to apply custom logic when determining whether to apply a potentially conflicting update received over a WAN.

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