IPAM - Concepts

Reviewed on 30 May 2024

CIDR notation

When viewing a private IP address in IPAM, it is shown in CIDR notation. For example, the address 172.16.12.2/22 represents the IPv4 address 172.16.12.2and its associated CIDR block 172.16.12.0/22, defined on the Private Network and containing 1024 addresses.

IPAM

IP Address Manager (IPAM) is Scaleway’s tool for planning, tracking and managing the IP address space of Scaleway products. It acts as a single source of truth for the IP addresses of Scaleway resources. Managed products, such as Databases and Load Balancer, are fully integrated into IPAM, and Private Networks’ DHCP server uses IPAM to assign private, static IP addresses to attached resources.

The public rollout of IPAM functionality is being carried out gradually. IPAM is now in General Availability, offering several different functionalities in the Scaleway console, including viewing, tagging and filtering all your private IP addresses. You can also reserve a private IP on one of your Private Networks and use it to attach an Instance, Load Balancer or Public Gateway to the network.

More functionality is planned for the future, including:

Support for attaching Managed Databases and Elastic Metal servers to a Private Network using a reserved IP address
Management of public (flexible) IP addresses

IPv4

Internet Protocol Version 4 is the standard protocol used for IP addresses, and routes most internet traffic as of today. Each IPv4 address has 32 bits. Written in human-readable form, an IPv4 address is generally shown as four octets separated by periods, e.g. 151.115.59.87.

Scaleway resources may have a public IPv4 address (flexible IP) for accessibility from the public internet, and will have a private IPv4 address for each Private Network they are attached to.

IPv6

Internet Protocol Version 6 is the most recent version of the IP protocol used for IP addresses. Each IPv6 address has 128 bits. Written in human-readable form, an IPv6 address can be shown as eight groups of four hexadecimal digits, each group representing 16 bits and separated by a colon, e.g. 2001:0DB8:0000:0003:0000:01FF:0000:002E. This can also be notated as 2001:DB8::3:0:1FF:0:2E.

IPv6-compatible Scaleway resources may have a public IPv6 address (flexible IP) for accessibility from the public internet, and will have a private IPv6 address for each Private Network they are attached to.

Private IP address

Private IP addresses identify devices on Private Networks. They are not routed on the public internet, and can be used to route traffic privately between resources attached to the Private Network, as well as to other Private Networks in the same VPC.

When you attach a resource to a Private Network, you can either specify a reserved IP address to use for the attachment, or let the Private Network’s DHCP assign it a private IPv4 address from the Private Network’s CIDR block. In both cases, the resource’s private IP address will not change unless you detach the resource from the Private Network, or delete the resource. IPv6 addresses can also be assigned for IPv6-compatible resources.

Four IP addresses from each CIDR block are unavailable for reservation/use: the first two and last two in the block. For example, for the subnet 172.16.12.0/22 the following addresses cannot be reserved or assigned to any resource: 172.16.12.0, 172.16.12.1, 172.16.15.254 and 172.16.15.256.

Public (flexible) IP address

Public IP addresses identify devices on the public internet. You can enter the public IP address of an Instance into any browser connected to the Internet, and access content being served from that Instance.

Depending on the type of resource and its configuration, it may or may not have a public IP address. For example, you can choose to give an Instance one or more public IP addresses (IPv4 and/or IPv6), or alternatively, no public IP address at all. Find out more about how to manage public connectivity in our best practices guide.

Public IP addresses at Scaleway are often called flexible IP addresses, because you can move them between different resources. However, flexible IP addresses are scoped to a single product and to a single Availability Zone. If you create a flexible IP address for an Instance in PAR-2, you can move it to a different Instance in PAR-2, but not to an Instance in PAR-1, nor to an Elastic Metal server in any AZ.

Reserved IP address

A reserved IP address is a private IP address from the CIDR block of a given Private Network, that you have reserved via IPAM. Reserving an IP means that it can no longer be auto-allocated by DHCP to resources that join the network. You can then use the reserved IP to attach a specified resource of your choice to the Private Network. After you detach the resource, the IP remains reserved, and you can either use it to attach a different resource, or release it back into the pool of generally available IPs.