In this codelab, you'll learn the differences between the legacy Google Compute Engine networking model, and the new Subnetwork model. Subnetwork allows you to create your own network topology as you would in your own on-premise datacenter, so that you can assign specific IP address ranges to groups of machines.
If you don't already have a Google Account (Gmail or Google Apps), you must create one. Sign-in to Google Cloud Platform console (console.cloud.google.com) and create a new project:
Remember the project ID, a unique name across all Google Cloud projects (the name above has already been taken and will not work for you, sorry!). It will be referred to later in this codelab as
Next, you'll need to enable billing in the Cloud Console in order to use Google Cloud resources.
Running through this codelab shouldn't cost you more than a few dollars, but it could be more if you decide to use more resources or if you leave them running (see "cleanup" section at the end of this document).
New users of Google Cloud Platform are eligible for a $300 free trial.
Very Important - Visit each of these pages to kick-off some initial setup behind the scenes, such as enabling the Compute Engine API:
Compute → Compute Engine → VM Instances
Once the operations completes, you will do most of the work from the Google Cloud Shell, a command line environment running in the Cloud. This Debian-based virtual machine is loaded with all the development tools you'll need (
git and others) and offers a persistent 5GB home directory. Open the Google Cloud Shell by clicking on the icon on the top right of the screen:
Finally, using Cloud Shell, set the default zone and project configuration:
$ gcloud config set compute/zone europe-west1-c $ gcloud config set compute/region europe-west1
You can pick and choose different zones too. Learn more about zones in Regions & Zones documentation.
Traditionally in Google Compute Engine, you define a single network IPv4 prefix range for all the virtual machine instances attached to that network, and that network spans all Cloud Platform regions.
Each instance within a network is assigned an IPv4 address from a global network IPv4 range. Instance IP addresses are not grouped by region or zone. One IP address might appear in one region, and its neighbor might be in a different region. Any given range of IPs can be spread across all regions, and the IP addresses of instances created within a region are not necessarily contiguous.
For example, if you have virtual machine instances in two Google Cloud regions, and different zones, each of the instance will be assigned an IP address from the global pool, like this:
As a result, in the legacy network mode, you won't be able to group your instances into different logical subnetworks like you do in your on-premise networks.
Google Compute Engine now supports creating your own subnetworks, and it's turned on by default for new projects. Read on to learn more.
You can let Google Compute Engine automatically create and manage subnetworks based on region. It can automatically assign a subnetwork IP prefix range to each region in your network. The instances created in a zone in a specific region in your network get assigned an IP allocated from the regional subnetwork range. This is the default mode for any new Google Cloud Platform projects.
You can see your current network setup two ways, from the Google Cloud Console, or from command line.
From the Google Cloud Console, click on the Menu icon on the top left of the screen:
Then navigate to Networking > Networks:
You will see that your project is already configured with automatic regional subnetworks, and there are different subnetworks created for each of the regions:
You can get the same information from the console. Start Cloud Shell, as instructed in the previous section, if you haven't done so already. In the shell, list existing networks:
$ gcloud compute networks list NAME MODE IPV4_RANGE GATEWAY_IPV4 default auto
It shows the default network with the automatic regional subnetwork mode. But to see the actual subnetwork ranges:
$ gcloud compute networks subnets list NAME REGION NETWORK RANGE default asia-northeast1 default 10.146.0.0/20 default us-west1 default 10.138.0.0/20 default us-east1 default 10.142.0.0/20 default europe-west1 default 10.132.0.0/20 default asia-east1 default 10.140.0.0/20 default us-central1 default 10.128.0.0/20
Let's create two different virtual machines, each in a different regions:
$ gcloud compute instances create instance-1 --zone us-east1-b Created [https://www.googleapis.com/compute/v1/projects/...]. NAME ZONE MACHINE_TYPE PREEMPTIBLE INTERNAL_IP EXTERNAL_IP STATUS instance-1 us-east1-b n1-standard-1 10.142.0.2 X.X.X.X RUNNING $ gcloud compute instances create instance-2 --zone us-central1-c Created [https://www.googleapis.com/compute/v1/projects/...]. NAME ZONE MACHINE_TYPE PREEMPTIBLE INTERNAL_IP EXTERNAL_IP STATUS instance-2 us-central1-c n1-standard-1 10.128.0.2 X.X.X.X RUNNING
Check their IP addresses, they should belong to the same subnetwork range for the respective region that the zone belongs to:
$ gcloud compute instances list NAME ZONE MACHINE_TYPE PREEMPTIBLE INTERNAL_IP EXTERNAL_IP STATUS instance-2 us-central1-c n1-standard-1 10.128.0.2 X.X.X.X RUNNING instance-1 us-east1-b n1-standard-1 10.142.0.2 X.X.X.X RUNNING
Custom Subnetworks allows you to manually define subnetwork IP range for each region in your network. There can be zero, one, or several subnetwork IP ranges created per region for a network. In order to create an instance in a zone, you must have previously created at least one subnetwork in that region. At instance creation time, you will need to specify the subnetwork in the region that the instance IP should be allocated from.
Let's create a new network topology that supports custom subnetworks:
$ gcloud compute networks create custom-network1 --subnet-mode custom Created [https://www.googleapis.com/compute/v1/projects/...]. NAME MODE IPV4_RANGE GATEWAY_IPV4 custom-network1 custom
Next, create a custom subnet in the
$ gcloud compute networks subnets create subnet-us-central-192 \ --network custom-network1 \ --region us-central1 \ --range 192.168.1.0/24 Created [https://www.googleapis.com/compute/v1/projects/...]. NAME REGION NETWORK RANGE subnet-us-central-192 us-central1 custom-network1 192.168.1.0/24
Next, create a custom subnet in the
$ gcloud compute networks subnets create subnet-europe-west-192 \ --network custom-network1 \ --region europe-west1 \ --range 192.168.5.0/24 Created [https://www.googleapis.com/compute/v1/projects/...]. NAME REGION NETWORK RANGE subnet-europe-west-192 europe-west1 custom-network1 192.168.5.0/24
You can then list all of your subnetworks:
$ gcloud compute networks subnets list NAME REGION NETWORK RANGE default asia-east1 default 10.140.0.0/20 default us-central1 default 10.128.0.0/20 subnet-us-central-192 us-central1 custom-network1 192.168.1.0/24 default europe-west1 default 10.132.0.0/20 subnet-europe-west-192 europe-west1 custom-network1 192.168.5.0/24 default us-east1 default 10.142.0.0/20
Then you can create instances in the different subnetworks:
$ gcloud compute instances create instance-3 \ --zone us-central1-a \ --subnet subnet-us-central-192 Created [https://www.googleapis.com/compute/v1/projects/...]. NAME ZONE MACHINE_TYPE PREEMPTIBLE INTERNAL_IP EXTERNAL_IP STATUS instance-3 us-central1-a n1-standard-1 192.168.1.2 X.X.X.X RUNNING $ gcloud compute instances create instance-4 \ --zone europe-west1-d \ --subnet subnet-europe-west-192 Created [https://www.googleapis.com/compute/v1/projects/...]. NAME ZONE MACHINE_TYPE PREEMPTIBLE INTERNAL_IP EXTERNAL_IP STATUS instance-4 europe-west1-d n1-standard-1 192.168.5.2 X.X.X.X RUNNING
In the automatic regional network, all virtual machine instances within a network can communicate with each other, because it automatically created firewall rules to open communication between the different regional networks. However, custom subnetworks do not have default firewall rules, so an instance in one custom subnetwork cannot reach an instance in another custom subnetwork.
To allow inter-subnetwork communication, you'll need to create firewall rules. We won't have time to go through this in the coding challenge lab. But you can learn more about this advanced topic in the Subnetwork documentation.
You now know the basics of the default network topology as well as the ability to create your own network topology on Google Cloud Platform!