OSDOCS-12623-update: Added extra parameters to the Ansible migration playbook doc

Author: dfitzmau

modules/nw-ovn-kubernetes-ansible-migration.adoc

@@ -16,6 +16,12 @@ As a cluster administrator, you can use an Ansible collection, `network.offline_
 
 * `playbooks/playbook-migration.yml`: Includes playbooks that execute in a sequence where each playbook represents a step in the migration process. 
 * `playbooks/playbook-rollback.yml`: Includes playbooks that execute in a sequence where each playbook represents a step in the rollback process. 
+
+[IMPORTANT]
+====
+If your cluster uses static routes or routing policies in the host network, ensure that you set the `routingViaHost` parameter to `true` and the `ipForwarding` parameter to `Global` in the `gatewayConfig` section of the `playbooks/playbook-migration.yml` file.
+====
+
 endif::rollback[]
 
 ifdef::rollback[]
@@ -109,6 +115,10 @@ ifndef::rollback[]
     migration_egress_ip: false
     migration_egress_firewall: false
     migration_multicast: false
+    migration_routing_via_host: true
+    migration_ip_forwarding: Global 
+    migration_cidr: "10.240.0.0/14"
+    migration_prefix: 23
     migration_mtu: 1400
     migration_geneve_port: 6081
     migration_ipv4_subnet: "100.64.0.0/16"
@@ -117,6 +127,9 @@ ifndef::rollback[]
 +
 `migration_interface_name`:: If you use an `NodeNetworkConfigurationPolicy` (NNCP) resource on a primary interface, specify the interface name in the `migration-playbook.yml` file so that the NNCP resource gets deleted on the primary interface during the migration process.
 `migration_disable_auto_migration`:: Disables the auto-migration of OpenShift SDN CNI plug-in features to the OVN-Kubernetes plugin. If you disable auto-migration of features, you must also set the `migration_egress_ip`, `migration_egress_firewall`, and `migration_multicast` parameters to `false`. If you need to enable auto-migration of features, set the parameter to `false`. 
+`migration_routing_via_host`:: A value of `true` sets local gateway mode and a value of `false` sets shared gateway mode for nodes in your cluster. The default value is `false`. In local gateway mode, traffic is routed through the host network stack. In shared gateway mode, traffic is not routed through the host network stack.
+`migration_ip_forwarding`:: Set IP forwarding to `Global` alongside the local gateway mode if you need the host network of the node to act as a router for traffic not related to OVN-Kubernetes.
+`migration_cidr`:: Specifies a Classless Inter-Domain Routing (CIDR) IP address block for your cluster. You cannot use any CIDR block that overlaps with the `100.64.0.0/16` CIDR block because the OVN-Kubernetes network provider uses this block internally. Ensure that you specify a prefix value, which is the slice of the CIDR block apportioned to each node in your cluster.
 `migration_mtu`:: Optional parameter that sets a specific maximum transmission unit (MTU) to your cluster network after the migration process.
 `migration_geneve_port`:: Optional parameter that sets a Geneve port for OVN-Kubernetes. The default port is `6081`.
 `migration_ipv4_subnet`:: Optional parameter that sets an IPv4 address range for internal use by OVN-Kubernetes. The default value for the parameter is `100.64.0.0/16`.