Physical networks layout¶

This section summarizes the requirements for the physical layout of underlay network and VLANs configuration for the multi-rack architecture of Mirantis OpenStack for Kubernetes (MOSK).

Physical networking of a Container Cloud management cluster¶

Due to limitations of virtual IP address for Kubernetes API and of MetalLB load balancing in Container Cloud, the management cluster nodes must share VLAN segments in the provisioning and management networks.

In the multi-rack architecture, the management cluster nodes may be placed to a single rack or spread across three racks. In either case, provisioning and management network VLANs must be stretched across ToR switches of the racks.

The following diagram illustrates physical and L2 connections of the Container Cloud management cluster.

../../_images/os-cluster-mgmt-physical.png

Physical networking of a MOSK cluster¶

External network¶

Since 23.2.2, MOSK supports full L3 networking topology in the Technology Preview scope. This enables deployment of specific cluster segments in dedicated racks without the need for L2 layer extension between them. For configuration procedure, see Configure BGP announcement for cluster API LB address and Configure BGP announcement of external addresses of Kubernetes load-balanced services in Deployment Guide.

If you configure BGP announcement for IP addresses of load-balanced services of a MOSK cluster, the external network can consist of multiple VLAN segments connected to all nodes of a MOSK cluster where MetalLB speaker components are configured to announce IP addresses for Kubernetes load-balanced services. Mirantis recommends that you use OpenStack controller nodes for this purpose.

If you configure ARP announcement for IP addresses of load-balanced services of a MOSK cluster, the external network must consist of a single VLAN stretched to the ToR switches of all the racks where MOSK nodes connected to the external network are located. Those are the nodes where MetalLB speaker components are configured to announce IP addresses for Kubernetes load-balanced services. Mirantis recommends that you use OpenStack controller nodes for this purpose.

Kubernetes manager nodes¶

Note

If BGP announcement is configured for MOSK cluster API LB address, Kubernetes manager nodes have no requirement to share the single stretched VLAN segment in the API/LCM network. All VLANs may be configured per rack.

If ARP announcement is configured for MOSK cluster API LB address, Kubernetes manager nodes must share the VLAN segment in the API/LCM network. In the multi-rack architecture, Kubernetes manager nodes may be spread across three racks. The API/LCM network VLAN must be stretched to the ToR switches of the racks. All other VLANs may be configured per rack. This requirement is caused by the Mirantis Kubernetes Engine underlay for MOSK relying on the Layer 2 VRRP protocol to ensure high availability of the Kubernetes API endpoint.

The following diagram illustrates physical and L2 network connections of the Kubernetes manager nodes in a MOSK cluster.

Caution

Such configuration does not apply to a compact control plane MOSK installation. See Create a MOSK cluster.

../../_images/os-cluster-k8s-mgr-physical.png

OpenStack controller nodes¶

The following diagram illustrates physical and L2 network connections of the control plane nodes in a MOSK cluster.

../../_images/os-cluster-control-physical.png

OpenStack compute nodes¶

All VLANs for OpenStack compute nodes may be configured per rack. No VLAN should be stretched across multiple racks.

The following diagram illustrates physical and L2 network connections of the compute nodes in a MOSK cluster.

../../_images/os-cluster-compute-physical.png

OpenStack storage nodes¶

All VLANs for OpenStack storage nodes may be configured per rack. No VLAN should be stretched across multiple racks.

The following diagram illustrates physical and L2 network connections of the storage nodes in a MOSK cluster.

../../_images/os-cluster-storage-physical.png