IP Addressing in Cloud Instances

In the cloud, VMR IP addresses are provided through the cloud service provider and cannot be configured on the VMR. Below are some notes and best practices.

  • A VMR can use any number of public IP addresses but only a single private IP address.
  • A VMR can be addressed through any of its IP addresses, however the VMR itself is only aware of its private address. For example, show commands will only show the internal address of the VMR.
  • Depending on the cloud provider, a user can control the IP addresses assigned to the VMR. For example, in AWS, there are typically two IP addresses, public and private, which can be controlled through AWS with Elastic IP, and Virtual Private Cloud settings. Other cloud providers will allow IP addressing with similar features.
  • When using multi-node routing and bridges on the VMR, care should be taken to ensure that security groups allow traffic to pass between VMRs on all of the IP addresses in use.
  • Multi-Node routing neighbors contain security measures to ensure that other end of the neighbor is the correct destination. This check is based on the remote private IP address. For more information on the correct configuration of neighbors, refer to Multi-Node Routing.
  • When a VMR is reachable through public and private IP addresses, it is preferred to use the internal address.
  • When configuring high-availability (HA) redundancy for VMRs, each node in the HA group must be configured with a private IP address, not a public IP address. Note that the private IP address can be displayed through the show ip vrf management command.