IP fabric is one the network cluster configuration types. This configuration type allows you to create virtual machines (VMs) with public IP addresses in a private network.
Virtual machines in the cluster are assigned IP addresses with the /32 mask. A separate virtual interface is used as the default gateway for each VM. Cluster nodes act as routers.
Routing in the cluster is performed using the iBGP protocol. Route Reflector (RR) equipment is used to transmit information about iBGP routes. Physical or virtual routers and/or servers can be used in this function. We recommend using at least two sets of RR equipment in one cluster — the main and the backup set.
To operate an IPv4 network in a cluster, use at least one set of RR equipment with an IPv4 address; for an IPv6 network, at least one set with an IPv6 address.
Advantages of IP fabric:
- reduced service traffic;
- saving the address space;
- isolation of VM traffic;
- IP addresses are not bound to cluster nodes;
- VMs can be migrated promptly among cluster nodes.
When creating a VM in an IP fabric cluster:
- VMmanager platform:
- Creates a separate virtual interface <vmname>_net0. For example, for a VM with the name sea_gold, the interface will be called sea_gold_net0. All virtual interfaces on the node will have the same IP and MAC addresses.
- Sets the IP address of the created interface as the gateway for the VM. Routing between the VM and the gateway is performed through a point-to-point connection (PtP).
- Adds the created route to the bird service configuration on the cluster node.
- The bird service transmits information about the created route via iBGP protocol to RR equipment.
- RR equipment transmits the route information to Core Gateway equipment. After that, the VM becomes available from the external network (Internet).
iBGP — dynamic routing protocol responsible for route exchange between nodes and network equipment.
Node 1, Node 2, Node 3 — cluster nodes.
VM1, VM2, VM3... — virtual machines.
VNET — virtual network interfaces.
Core Gateway — equipment that provides access to the external network (Internet).
BIRD — service on the cluster node that implements the iBGP protocol.
Linux CORE — OS core of cluster node.
Route Reflector — server or network equipment that receives route information from nodes and transmits it to Core Gateway.
Backup Route Reflector — backup set of Route Reflector equipment.
- In VMmanager:
- Create an IP pool for the VMs. Read more in Pools management.
- Create a cluster with the IP fabric network configuration type. Read more in Creating a cluster. When creating the cluster, specify the following:
- gateway IP address for the VM. VMmanager will assign this address of the gateway to all virtual interfaces on the cluster node and use it only to route the VM inside the node. As IP address, you can specify any address that will not coincide with those used in the cluster node.
- BGP community.
- IP addresses and numbers of autonomous systems of RR equipment.
Add the nodes to the cluster. Read more in Managing servers in the cluster.
The nodes of the IP-fabric with KVM virtualization must have CentOS 8, with LXD virtualization - Ubuntu 20.
- Configure BGP sessions for each cluster node on the RR equipment: specify the IP addresses of nodes and numbers of autonomous BGP systems in the settings.