:_mod-docs-content-type: ASSEMBLY
[id="migration-from-version-3-to-4-overview"]
= Migration from OpenShift Container Platform 3 to 4 overview
include::_attributes/common-attributes.adoc[]
:context: migration-from-version-3-to-4-overview

toc::[]

{product-title} 4 clusters are different from {product-title} 3 clusters. {product-title} 4 clusters contain new technologies and functionality that result in a cluster that is self-managing, flexible, and automated. To learn more about migrating from {product-title} 3 to 4 see xref:../migrating_from_ocp_3_to_4/about-migrating-from-3-to-4.adoc#about-migrating-from-3-to-4[About migrating from OpenShift Container Platform 3 to 4].

[id="mtc-3-to-4-overview-differences-mtc"]
== Differences between {product-title} 3 and 4
Before migrating from {product-title} 3 to 4, you can check xref:../migrating_from_ocp_3_to_4/planning-migration-3-4.adoc#planning-migration-3-4[differences between {product-title} 3 and 4]. Review the following information:

* xref:../architecture/architecture.adoc#architecture[Architecture]
* xref:../architecture/architecture-installation.adoc#architecture-installation[Installation and update]
* xref:../storage/index.adoc#index[Storage], xref:../networking/networking_overview/understanding-networking.adoc#understanding-networking[network], xref:../security/index.adoc#index[security], and xref:../observability/monitoring/about-ocp-monitoring.adoc#about-ocp-monitoring[monitoring considerations]

[id="mtc-3-to-4-overview-planning-network-considerations-mtc"]
== Planning network considerations
Before migrating from {product-title} 3 to 4, review the xref:../migrating_from_ocp_3_to_4/planning-migration-3-4.adoc#planning-migration-3-4[differences between {product-title} 3 and 4] for information about the following areas:

* xref:../migrating_from_ocp_3_to_4/planning-considerations-3-4.adoc#dns-considerations_planning-considerations-3-4[DNS considerations]
** xref:../migrating_from_ocp_3_to_4/planning-considerations-3-4.adoc#migration-isolating-dns-domain-of-target-cluster-from-clients_planning-considerations-3-4[Isolating the DNS domain of the target cluster from the clients].
** xref:../migrating_from_ocp_3_to_4/planning-considerations-3-4.adoc#migration-setting-up-target-cluster-to-accept-source-dns-domain_planning-considerations-3-4[Setting up the target cluster to accept the source DNS domain].
