GCP Cloud : Day 07 - GCP Virtual Private Cloud (VPC)

• A VPC (Virtual Private Cloud) is a private virtual network inside GCP where you deploy resources like VM instances, GKE clusters, Load balancers, Cloud SQL, Serverless connectors etc.
• It gives Isolation, Routing, Firewalling, Hybrid connectivity, Internal communication.
• GCP VPC is a global resources.

Core Components of GCP VPC

1. VPC Network

VPC is a main logical container which holds all the networking related resources. A project can have multiple VPCs.

Project
├── prod-vpc
├── dev-vpc
└── shared-services-vpc

Types of VPC in GCP

• Auto Mode VPC

Google creates subnets automatically in every region. Example:

default-vpc
├── us-central1
├── asia-south1
├── europe-west1

Good for testing, learning, not recommended for production.

• Custom Mode VPC

In custom VPC user define everything. Example

prod-vpc
├── app-subnet
├── db-subnet
└── management-subnet

This type of VPC is best for production.

2. Subnets

Subnets are where IP ranges are assigned.

prod-vpc
├── us-central1-subnet → 10.10.0.0/24
├── asia-south1-subnet → 10.20.0.0/24
└── europe-west1-subnet → 10.30.0.0/24

• VPC are Regional resources.
• Can expand CIDR.
• Multiple subnets in one VPC.

3. Routes

Routes decide how packets travel.

Types:

• System Routes (Automatic)

Created automatically:

10.10.0.0/24 → local subnet
10.20.0.0/24 → local subnet 
0.0.0.0/0 → internet gateway

• Custom Routes

Used for VPN, NAT appliances, Custom next hops.

4. Firewall Rules

Firewall Rules control inbound and outbound traffic. Rules apply at Network level, Target tags, Service accounts.

Types of Firewall Rules:

• Ingress Rules (Incoming traffic) : Controls traffic coming into a VM.

Example: Allow SSH from your office IP.

Source: 203.0.113.10/32
Protocol: TCP
Port: 22
Action: Allow

Flow:

Internet → VM

• Egress Rules (Outgoing traffic) : Controls traffic leaving a VM.

Example: Allow HTTPS to internet.

Destination: 0.0.0.0/0
Protocol: TCP
Port: 443
Action: Allow

Flow:

VM → Internet