Overview

VDC networking enables the seamless interconnection of resources within your infrastructure, allowing for efficient communication and resource sharing across compute, storage, and application layers. Virtual networks (VNets) function similarly to traditional physical networks but offer enhanced flexibility, scalability, and automation through Software-Defined Networking (SDN).

Each virtual network is logically isolated, ensuring that data transmitted within a subnet remains completely segregated from other subnets and external entities. Built-in security mechanisms such as network security groups (NSGs), route tables, and optional firewall appliances help enforce access controls and protect against unauthorized traffic. This ensures that the virtual network is secure by design and that data remains private and inaccessible to other users or tenants in multi-tenant environments.

By design, the IONOS Cloud does not expose any physical or virtual switches. Instead, we have deeply integrated switching, routing, and forwarding capabilities directly into our network stack, allowing us to handle all traffic distribution internally. If you need to route traffic between your private networks using a Virtual Machine (VM), you must configure the VM to perform routing functions and update the relevant route tables accordingly.

IP Addresses

By default, IP addresses are assigned by our DHCP server. You can also assign IP addresses yourself. MAC addresses cannot be modified. For more information, see IP Addresses.

Local Area Network (LAN)

There are two primary types of networks:

• Public: A public network exposes selected resources to the internet or other external networks, allowing inbound and outbound traffic under controlled security policies.

• Private: A private network enables secure communication between internal resources, isolating traffic from external access. You can define and manage both network types based on your infrastructure needs and access requirements.

When you drag and place the internet icon to an existing configuration, a private LAN is converted into a public LAN. Remember that the process also converts all the private IP addresses into public IP addresses. For more information, see LANs.

IP Failover

IP Failover enables automatic reassignment of public IP addresses to standby virtual machines in the event of a failure, ensuring uninterrupted service availability. For more information, see IP Failover.

NIC-based Firewall

To protect your network against unauthorized access or attacks from the Internet, you can activate one of the supported firewalls for each NIC: Ingress, Egress, or Bidirectional. By default, the firewall activation blocks all traffic. However, you can configure rules to specify what traffic can pass through. You can specify rules for individual source or target IPs for TCP, UDP, ICMP, ICMPv6, VRRP, GRE, AH, and ESP protocols. For more information, see NIC-based Firewall.

NIC Multi-Queue

NIC Multi-Queues enable network interface cards (NICs) to process multiple data streams in parallel, improving network throughput and reducing bottlenecks on multi-core systems. By distributing incoming and outgoing packets across several hardware queues, NIC Multi-Queues allow the operating system and applications to leverage multiple CPU cores for network processing. For more information, see NIC Multi-Queue.

VDC Networking workflow

1. Plan your network architecture

Determine an IP address schema, the number of virtual networks, and which networks require internet access or internal-only access. Consider CIDR blocks for subnets and overall network design.

2. Routing and forwarding design

Determine routing protocols, such as BGP, OSPF, for internal and external connectivity. Design default gateways and routing paths for VDC networks. Plan for cross-connects if multiple VDCs are involved.

3. Define network security policies

Design network security policies and configure Network Security Groups (NSGs) and firewall rules to protect your resources. For more information, see Firewall.

4. Set up Compute resources

Set up your virtual machines and compute resources according to your architecture plan. For more information, see Compute Engine.

5. Configure LAN

Create and configure your private and public networks. For more information, see LANs.

6. Configure IP Addresses

Reserve static IP addresses or use DHCP addresses provided by IONOS Cloud for your resources. For more information, see IP Addresses.

7. Enable NIC Multi-Queue

For improved network performance on multi-core systems, enable NIC Multi-Queue on your virtual machines. For more information, see NIC Multi-Queue.

8. Implement High Availability

Configure IP failover groups for critical resources to ensure continuous availability. For more information, see IP Failover.