Latchu@DevOps

Posted on Sep 18

Part-64: 🌐 Google Cloud Networking – Hands-on with VPC Network Peering in GCP Cloud

#googlecloud #vpc #cloud #devops

In real-world cloud projects, you often need to connect two isolated VPC networks so their resources can communicate securely over internal IPs—without exposing them to the internet.

This is where VPC Network Peering comes in. It provides low-latency, private communication between VPCs while keeping them administratively separate.

In this demo, we’ll set up two VPCs, create subnets and VM instances, test connectivity, and then enable VPC Peering to allow secure internal communication.

🔹 Step 01: Introduction

We will:

Create two VPCs (vpc1 and vpc2)
Create subnets in each (vpc1subnet, vpc2subnet)
Create VMs inside each subnet (vpc1-vm, vpc2-vm)
Test ping between VMs (will fail initially)
Configure VPC Peering between the VPCs
Re-run ping test (should succeed now 🎉)

🔹 Step 02: Create VPC1 and Subnet

VPC1 Setup

Name: vpc1
Mode: Custom
Firewall rules: allow-ssh, allow-icmp, allow-custom
Routing: Default (Global)

Subnet for VPC1

Name: vpc1subnet
Region: us-central1
CIDR: 10.1.0.0/16

🔹 Step 03: Create VPC2 and Subnet

VPC2 Setup

Name: vpc2
Mode: Custom
Firewall rules: allow-ssh, allow-icmp, allow-custom
Routing: Default (Global)

Subnet for VPC2

Name: vpc2subnet
Region: us-central1
CIDR: 10.8.0.0/16

🔹 Step 04: Create VM Instances

# Set Project
gcloud config set project gcpdemos

# VM in vpc1subnet
gcloud compute instances create vpc1-vm \
    --zone=us-central1-a \
    --machine-type=e2-micro \
    --network-interface=subnet=vpc1subnet

# VM in vpc2subnet
gcloud compute instances create vpc2-vm \
    --zone=us-central1-a \
    --machine-type=e2-micro \
    --network-interface=subnet=vpc2subnet

🔹 Step 05: Test Initial Connectivity

# Connect to vpc1-vm
gcloud compute ssh vpc1-vm --zone=us-central1-a --project=gcpdemos

# Try ping vpc2-vm internal IP
ping <vpc2-vm-internal-ip>
# ❌ Should FAIL

# Connect to vpc2-vm
gcloud compute ssh vpc2-vm --zone=us-central1-a --project=gcpdemos

# Try ping vpc1-vm internal IP
ping <vpc1-vm-internal-ip>
# ❌ Should FAIL

🔹 Step 06: Configure VPC Peering

From VPC1 → VPC2

Go to VPC Network -> VPC network peering -> CREATE PEERING CONNECTION
Name: vpc1-to-vpc2-peering
Your VPC: vpc1
Peer Project: gcpdemos
Peer VPC: vpc2
Enable import/export subnet routes

From VPC2 → VPC1

Name: vpc2-to-vpc1-peering

Go to VPC Network -> VPC network peering -> CREATE PEERING CONNECTION
Name: vpc2-to-vpc1-peering
Your VPC: vpc2
Peer Project: gcpdemos
Peer VPC: vpc1
Enable import/export subnet routes

Step-07: Verify VPC Peering connection status

Go to VPC Network -> VPC network peering -
Check status → Both connections should be ACTIVE ✅

🔹 Step 08: Verify Connectivity After Peering

# From vpc1-vm → vpc2-vm
gcloud compute ssh vpc1-vm --zone=us-central1-a --project=gcpdemos
ping <vpc2-vm-internal-ip>
# ✅ Should PASS

# From vpc2-vm → vpc1-vm
gcloud compute ssh vpc2-vm --zone=us-central1-a --project=gcpdemos
ping <vpc1-vm-internal-ip>
# ✅ Should PASS

🔹 Step 09: Cleanup

Delete the 2 VM's
Delete the VNET Peering connections
Delete the 2 VPC's

🎯 Summary

Before Peering → VMs in different VPCs cannot talk
After Peering → Private, low-latency connectivity works over internal IPs
Use Cases:

Multi-project architecture
SaaS providers exposing services securely
Connecting dev/test VPCs with shared services VPC

🔥 With just a few steps, you’ve enabled private communication between VPCs in Google Cloud using VPC Network Peering.

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