Guide: Network Configuration by Region

This guide provides details of the VM networks in each bwCloud-OS region. It describes which networks are available by default, which can be requested, and how IPv4 and IPv6 connectivity is provided.

While core networking concepts are consistent across regions, available networks, IP address ranges, and access methods may differ. Please refer to the section for your specific region.

Freiburg

• Information for this region will be provided soon.*

Karlsruhe

The Karlsruhe region provides a default routed network, as well as additional networks that can be assigned to projects upon request.

Default Network

• All projects have access to the default network default-network.
• Instances connected to this network receive:
  • A public IPv6 address
  • A private IPv4 address

This is a routed network using an OpenStack router connected to an external provider network.

• IPv6: Direct public connectivity
• IPv4 (egress): Provided via SNAT through the router
• IPv4 (ingress): Not available by default (see IPv4 Ingress via Floating IPs)
• This Network is shared between all projects

IPv4 Ingress via Floating IPs

• Floating IPs are allocated from the external network provider-network.
• They can be assigned to projects upon request via a support ticket.

Once assigned, a Floating IP can be associated with an instance to provide IPv4 ingress connectivity.

Seperated Networks

If you require a seperated Broadcast Domain you can request one via a support ticket.

The network will:

• receive a separate private IPv4 Subnet
• receive a separate public IPv6 Subnet
• have a separated Broadcast Domain only accessible by authorized projects
• always use up at least one public IPv4 used for the virtual Router

Migration from Gen2 to Gen3

The Karlsruhe region is currently operating two environments in parallel:

• Gen2 (legacy cloud)
• Gen3 (current bwCloud-OS environment)

This setup allows users to migrate their instances and data from Gen2 to Gen3.

• The coexistence period will last until 31. August 2026.

After the transition period:

• All IP addresses (Routers and Floating IPs) from provider-network will be migrated to a new IPv4 Subnet.
• This migration will be performed by administrators; no user action is required.
• During the Migration all Floating IPs will be redistributed and some minor connection interruptions will happen.

Mannheim

The Mannheim region provides a default routed network, as well as additional networks that can be assigned to projects upon request. Both IPv6 and IPv4 connectivity options are available, depending on the selected network.

Default Network

• All projects have access to the default network routed_default_net.
• Instances connected to this network receive:
  • A public IPv6 address
  • A private IPv4 address

This is a routed network using an OpenStack router connected to an external provider network:

• IPv6: Direct public connectivity
• IPv4 (egress): Provided via SNAT through the router
• IPv4 (ingress): Not available by default (see IPv4 Ingress via Floating IPs)

📌 Note: This network extends the legacy IPv6-only network in the Mannheim region, which did not provide IPv4 connectivity. Before requesting an IPv4 address via a support ticket, please ensure that the combined connectivity is not already sufficient for your use case.

IPv4 Ingress via Floating IPs

• Floating IPs are allocated from the external network provider_default_net.
• They can be assigned to projects upon request via a support ticket.

Once assigned to a project, a Floating IP can be associated with an instance to provide IPv4 ingress connectivity.

Flat External Networks

• There are also flat external networks available, such as provider_interim_net .
• They can be assigned to projects via a support ticket.

Instances connected directly to this type of network receive:

• A public IPv4 address
• A public IPv6 address

This enables dual-stack public connectivity (IPv4 and IPv6) without the need for Floating IPs.

Migration from Gen2 to Gen3

The Mannheim region is currently operating two environments in parallel:

• Gen2 (legacy cloud)
• Gen3 (current bwCloud-OS environment)

This setup allows users to migrate their instances and data from Gen2 to Gen3.

• The coexistence period will last until 31. August 2026.
• During this period, provider_interim_net is used as the flat external network.

After the transition period:

• All dual-stack IP addresses from provider_interim_net will be migrated to provider_default_net. This migration will be performed by administrators; no user action is required.
• Projects requiring a flat external network will be assigned provider_default_net.

📌 Note: We do not recommend allocating Floating IPs from the provider_interim_net, because they will be lost after the transition period. Instead, request and associate them from provider_default_net.

Ulm

Default Network

• All projects have access to the default network virt-shared.
• Instances connected to this network receive:
  • A public global IPv6 address
  • A private NAT-ed IPv4 address

This is a routed network using an OpenStack router connected to an external provider network:

• IPv6: Direct public connectivity
• IPv4 (egress): Provided via SNAT through the router
• IPv4 (ingress): Optional and possible via Floating IPs

IPv4 Ingress via Floating IPs

• Optional Floating IPs can allocated from the external network public-link quota permitting.
• Once assigned to a project, a Floating IP can be associated with an instance to provide IPv4 ingress connectivity for that instance.
• Incoming requests to the Floating IP will be relayed by the router to the instance's private IPv4 and vice-versa (DNAT + SNAT).
• The instance internally only sees its private IPv4, but through the Floating IP external requests will arrive at its private IPv4.

Flat External Networks

• There are no flat networks available to users in region Ulm.

Per Project Networks

• If a project with multiple VMs wishes to use a separate network instead of relying on the virt-shared network, it is possible to allocate a private network.
• Private networks have the same properties and limitations as the shared virt-shared network, but receive a smaller private IPv4 range and are not shared with other projects.
• A VM in a dual-stacked private network will receive a private, NAT-ed IPv4 and a public, global IPv6 address.
  • A unique, private IPv4 /26 range can be allocated from the subnet pool tenant-v4-16-26.
  • A unique, public IPv6 /64 range can be allocated from the subnet pool tenant-v6-48-64.
• Optional Floating IPs from public-link can be used for IPv4 ingress, just like with the default virt-shared network.
• The only meaningful advantage of a per project network is that is not shared with VMs from other projects.

Network Renumbering

• The IPv4 range that Gen3 region Ulm starts with initially is only temporary and will be replaced with an IPv4 range that is currently still in-use in Gen2 region Ulm, once Gen2 shuts down.
  • During that IPv4 renumbering all IPv4 Floating IPs will be removed.
  • Afterwards new IPv4 Floating IPs can be allocated from public-link.
  • This affects virt-shared and all per project networks.
  • IPv6 will remain unchanged.