W-17684691-CIDR-block-size-recomm

cloudhub-2/modules/ROOT/pages/ps-gather-setup-info.adoc

@@ -144,6 +144,36 @@ Asia Pacific (Tokyo)
 [[cidr-block]]
 include::partial$create-config.adoc[tag=cidrBlock,leveloffset=+2]
 
+[[cidr-block-sizing]]
+==== CIDR Block Sizing
+
+CIDR block sizing depends on several factors related to how IP addresses are allocated when you deploy applications:
+
+* Number of applications in a private space
+* xref:ch2-architecture.adoc#cloudhub-2-replicas[Replica size] assigned to each application
+* xref:ch2-clustering.adoc#replica-scale-out[Number of replicas] in each application, based on horizontal scaling, high availability, and fault tolerance configuration
+* xref:ch2-update-apps.adoc#rolling-update-vs-recreate-deployment-model[Rolling deployment configuration]
+* xref:ch2-patch-updates.adoc[Auto-upgrades] that update multiple applications simultaneously
+* Platform internal operations or services that require IP headroom
+
+Use the following reference table to select the appropriate CIDR block size for your private space:
+
+[%header%autowidth.spread]
+|===
+|CIDR Block Size |Maximum vCores |Maximum Applications
+|`/24` |Less than 100 |Less than 100
+|`/23` |Less than 300 |Less than 200
+|`/22` |Less than 600 |Less than 500
+|`/21` |Less than 1200 |Less than 1000
+|`/20` |Less than 3000 |Less than 2000
+|===
+
+[NOTE]
+====
+These reference sizes are subject to change as the platform continues to evolve. Exceeding the recommended thresholds for your CIDR block size can cause application deployments to fail with errors indicating that replicas are unschedulable due to insufficient available IP addresses.
+====
+
+
 [[unusable-cidr]]
 ==== Unusable Private Space Network CIDR