CIDR

This topic provides an overview of managing IP addresses with Classless Inter-Domain Routing (CIDR) in OTCAD.

CIDR

Cloud infrastructure engineers use CIDR notation to manage IP address ranges for cloud-based networks. IP addresses enable resources in your Virtual Private Cloud (VPC) to communicate with each other and with resources over the Internet. CIDR notation is a way to represent an IP address and its network mask.

OpenText supports ranges of IP addresses using Classless Inter-Domain Routing (CIDR) notation. For example, 192.168.1.0/24 represents all IPv4 addresses in the range of 192.168.1.0 to 192.168.1.255.

The format of these addresses is as follows:

  • An individual IPv4 address is 32 bits, with 4 groups of up to 3 decimal digits. For example, 10.0.1.0.
  • An individual IPv6 address is 128 bits, with 8 groups of 4 hexadecimal digits. For example, 2001:0db8:85a3:0000:0000:8a2e:0370:7334.

Public IPv4 and IPv6 addresses

All subnets have an attribute that determines whether a network interface created in the subnet automatically receives a public IPv4 address. Therefore, when you launch an instance into a subnet that has this attribute enabled, a public IP address is assigned to the primary network interface that's created for the instance. You can control whether your instance receives a public IP address by doing the following:

  • Modifying the public IP addressing attribute of your subnet.
  • Enabling or disabling the public IP addressing feature during instance launch, which overrides the subnet's public IP addressing attribute.
  • Unassigning a public IP address from your instance after launch by managing the IP addresses associated with a network interface.

Public IPv6 addresses are IPv6 addresses that can be configured to remain private or configured to be reachable over the Internet.

Private IPv4 and IPv6 addresses

Private IPv4 addresses are not reachable over the Internet and can be used for communication between the instances in your VPC. When you launch an instance into a VPC, a primary private IP address from the IPv4 address range of the subnet is assigned to the primary network interface (for example, eth0) of the instance. Each instance is also given a private (internal) DNS hostname that resolves to the private IP address of the instance.

You cannot share private IPv6 addresses on the Internet. You can use a private IPv6 address if you want your private networks to support IPv6 and you have no intention of routing traffic from these addresses to the Internet. You can connect to the internet from a resource that has a private IPv6 address. But you must route traffic through a resource in another subnet with a public IPv6 address.

Configure CIDR settings

To configure CIDR settings:

  1. In the Settings Overview page, select View CIDR. The CIDR page displays.
  2. Select Private.
  3. To add an IP address, select Add IP.
  4. From the Value drop-down list, select either IPv4 or IPv6 depending on the IP address you want to add. Do one of the following: a. Enter a valid IPv4 or IPv6 address. b. Copy a valid IPv4 or IPv6 address from another source and select Paste.
  5. Select √.