1. Home
  2. Training Library
  3. Google Cloud Platform
  4. Courses
  5. Troubleshooting Virtual Machine Networking Issues on GCP

Network Traffic Dropping


Troubleshooting VN Networking Issues
SSH Errors
Network Traffic Dropping

In this course, we’ll go over some of the most common networking issues when connecting to or from a virtual machine on Google Cloud Platform. We’ll cover what to do when you get an SSH error or when you discover that network traffic between your VM instance and other systems is dropping.

Learning Objectives

  • Troubleshoot the most common networking issues when connecting to or from a virtual machine on Google Cloud Platform 

Intended Audience

  • Anyone who works with virtual machine instances on Google Cloud Platform




Another problem you might run into is network traffic dropping between an instance and other systems. The first thing to check is the firewall rules for the network the instance is in. The default network has firewall rules that allow http, https, and a few other protocols. If any of those rules were deleted, that could be the reason for your network issues.

If instead of putting the instance in the default network, you put it in another network that you created, then make sure you created the appropriate firewall rules. When you create a new network, it doesn’t come with any firewall rules, so you have to create some to allow any traffic.

Another potential reason for network traffic dropping is the idle connection timeout. Idle TCP connections are disconnected after 10 minutes. If your instance initiates or accepts long-lived connections, then you should adjust the TCP keep-alive settings. This will prevent connections from being dropped by the idle timeout. 

Since the timeout is 10 minutes, you need to set the TCP keep-alive to something less than 10 minutes so connections will never be idle for that long. You need to set the keep-alive on either the instance or the external client, depending on which side initiates connections.

Be aware that you should only set a TCP keep-alive if you are having problems with connection timeouts. If you’re not having that sort of problem, then setting a TCP keep-alive will just increase network traffic for no good reason.

And that’s it for troubleshooting VM networking issues on GCP. Please give this course a rating, and if you have any questions or comments, please let us know. Thanks!

About the Author
Learning Paths

Guy launched his first training website in 1995 and he's been helping people learn IT technologies ever since. He has been a sysadmin, instructor, sales engineer, IT manager, and entrepreneur. In his most recent venture, he founded and led a cloud-based training infrastructure company that provided virtual labs for some of the largest software vendors in the world. Guy’s passion is making complex technology easy to understand. His activities outside of work have included riding an elephant and skydiving (although not at the same time).