Configure Networking in OpenStack: Step-by-Step Guide

How to Configure Networking in OpenStack

Configuring networking in OpenStack can seem daunting at first, but this guide will walk you through each step to set up and manage your network effectively. OpenStack uses Neutron for network connectivity management, facilitating everything from network interface management to load balancing.

Prerequisites

Administrator access to an OpenStack deployment
Familiarity with network concepts like subnets and routers
Access to the OpenStack CLI or Horizon dashboard
Basic understanding of Linux networking

Step 1: Network Setup

Start by setting up your network and subnets. Navigate to the OpenStack dashboard or use the CLI to create a new network.

openstack network create mynetwork

Create a subnet within this network:

openstack subnet create --network mynetwork --subnet-range 192.168.0.0/24 mysubnet

Step 2: Configure Virtual Routers

To enable traffic routing between different networks and external access, you first need to set up a virtual router:

openstack router create myrouter

Add an interface to this router with your subnet:

openstack router add subnet myrouter mysubnet

Step 3: External Network and Gateway Setup

Assign an external network to your router to enable external connectivity. Typically, the administrator pre-configures this step, so confirm with your cloud provider if you are a tenant.

openstack router set --external-gateway public_network myrouter

Step 4: Launch Instances with Network Access

Deploy instances onto your network with networks attached:

openstack server create --flavor m1.small --image cirros --nic net-id=$(openstack network show mynetwork -c id -f value) myinstance

Step 5: Security Groups and Rules

Security groups control incoming and outgoing traffic to instances. By default, instances may not receive SSH or ICMP (ping) requests. Add rules to permit these:

openstack security group rule create --proto tcp --dst-port 22 --ingress default

Create a similar rule for ICMP:

openstack security group rule create --proto icmp default

Step 6: Troubleshooting Common Issues

If instances cannot access external networks:

Check that the correct router is set and has an external gateway.
Verify the security group rules allow the desired protocol.
Ensure associated subnet CIDR aligns with your network plan.

For internal link, check our guide on How to Install OpenStack.

Summary Checklist

Networks and subnets are properly defined and linked.
Routers have subnets and external gateways correctly configured.
Instances have the correct network access and are tagged to appropriate security groups.
Security rules are established to permit necessary traffic.