Routes and routing in GCP - Commands & Configuration

Introduction

Routes in Google Cloud help direct network traffic from one place to another. Routing decides how data moves between virtual machines or to the internet, making sure it reaches the right destination.

When you want to control how traffic flows between virtual machines in your cloud network.

When you need to send traffic from your cloud network to the internet or other networks.

When you want to block or allow certain traffic by directing it through specific paths.

When you have multiple networks and want to connect them with clear traffic rules.

When you want to troubleshoot network issues by checking how routes are set up.

Commands

This command creates a route named 'example-route' in the 'default' network. It directs traffic destined for the 10.0.0.0/24 range to the virtual machine 'example-vm' in the specified zone.

Terminal

gcloud compute routes create example-route --network default --destination-range 10.0.0.0/24 --next-hop-instance example-vm --next-hop-instance-zone us-central1-a

Expected Output

Created [https://www.googleapis.com/compute/v1/projects/my-project/global/routes/example-route].

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--network - Specifies the network where the route is created.

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--destination-range - Defines the IP range this route applies to.

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--next-hop-instance - Sets the VM that traffic will be sent to.

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--next-hop-instance-zone - Specifies the zone of the next hop instance.

This command lists the route named 'example-route' to verify it was created and see its details.

Terminal

gcloud compute routes list --filter="name=example-route"

Expected Output

NAME           NETWORK  DEST_RANGE    NEXT_HOP_INSTANCE          NEXT_HOP_IP  PRIORITY  TAGS

example-route  default  10.0.0.0/24  projects/my-project/zones/us-central1-a/instances/example-vm             1000

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--filter - Filters the list to show only the route with the specified name.

This command deletes the route named 'example-route' without asking for confirmation, cleaning up the route after use.

Terminal

gcloud compute routes delete example-route --quiet

Expected Output

Deleted [https://www.googleapis.com/compute/v1/projects/my-project/global/routes/example-route].

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--quiet - Skips confirmation prompt for deletion.

Key Concept

If you remember nothing else from this pattern, remember: routes tell your cloud network where to send traffic based on destination addresses.

Common Mistakes

Using the wrong network name when creating a route.

The route will not apply to the intended network, so traffic won't be directed correctly.

Always check and specify the correct network name with the --network flag.

Setting an incorrect destination IP range.

Traffic outside the correct range won't follow the route, causing connectivity issues.

Verify the destination range matches the IP addresses you want to route.

Not specifying the correct next hop instance or zone.

Traffic will not reach the intended virtual machine, breaking communication.

Use the exact VM name and zone where the next hop instance is located.

Summary

Create routes to control where network traffic goes in your cloud network.

Use 'gcloud compute routes create' with destination range and next hop to set routes.

List routes to check their details and delete them when no longer needed.