Google Cloud Platform - Virtual Private Cloud (VPC)

            
 

            

        

          

     
          

         

                 
          
 





  
  

    
A Virtual Private Cloud (VPC) is a global, private, isolated virtual network partition within Google Cloud. It provides networking functionality to Compute Engine VM instances, GKE clusters, and the App Engine flexible environment.


    
1. Core Components

    
    
        
  • Subnets: Regional resources that define IP address ranges.
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  • Firewall Rules: Control traffic to and from instances (Ingress/Egress).
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  • Routes: Define paths for traffic to leave the VPC (e.g., Default Internet Gateway).
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  • Cloud Router: Enables dynamic exchange of routes between your VPC and on-premises networks.
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2. VPC vs. Subnet Comparison

    

        
            

                Feature
                VPC (Global)
                Subnet (Regional)
            

        
        
            

                Scope
                Global (Spans all regions)
                Regional (Tied to one region)
            

            

                Definition
                The entire virtual network
                A specific IP range (CIDR)
            

            

                Communication
                Resources can talk privately across regions
                Organizes resources by geography
            

        
    


    

    

        
Practical Example: Two-Tier Architecture

        
Imagine a secure banking app:

        
    
            
  • Web Tier: Located in a Public Subnet with an External IP for customer access.
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  • Database Tier: Located in a Private Subnet with no External IP.
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  • Security Logic: A Firewall rule is set to only allow traffic into the Database Subnet if it originates from the Web Tier's internal IP range.
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3. Steps to Launch a VPC on GCP

    
    
        
  1. Navigate: Open the GCP Console and go to VPC network > VPC networks.
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  2. Initiate: Click Create VPC Network at the top of the page.
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  3. Configure Name: Provide a unique name (e.g., prod-vpc-network).
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  4. Set Subnet Mode: Choose Custom. This allows you to manually define subnets and IP ranges for better security.
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  5. Add a Subnet:
            
      
                
    • Name: subnet-us-east
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    • Region: us-east1
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    • IP Address Range: 10.0.1.0/24
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  6. Select Firewall Rules: Check basic rules like allow-ssh or allow-icmp to allow initial connectivity.
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  7. Finalize: Scroll to the bottom and click Create.
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