CDL
Deep Dive
Global VPC, Cloud Load Balancing, Cloud CDN, Cloud DNS, Cloud Interconnect, and Cloud VPN. Google Cloud's network and its key differentiators.
Google Cloud's VPC is global by default. A single VPC can have subnets in multiple regions around the world. This contrasts with AWS and Azure, where VPCs are regional.
GCP VPC (global)
One VPC = multiple regions. Resources in us-east1 and europe-west1 can be in the same VPC and communicate over private IPs without peering.
AWS VPC (regional)
Each VPC is limited to one region. You need VPC Peering or Transit Gateway to connect resources across multiple regions.
| VPC concept | Description |
|---|---|
| Subnets | Regional (not per zone). A subnet covers all zones in a region. VMs in different zones of the same region can be in the same subnet. |
| Firewall rules | Stateful firewall rules at the VPC or instance level. Allow/block inbound/outbound traffic by IP, protocol, port, and tags. |
| Cloud NAT | Allows VMs without a public IP to access the internet (for updates, downloads) without exposing the VMs directly. |
| Shared VPC | Shares a VPC across multiple GCP projects. The host project controls the network; service projects use its subnets. |
| VPC Peering | Connects two GCP VPCs (same or different project) at the private network level. Not transitive: A-B and B-C doesn't imply A-C. |
| Private Google Access | Allows VMs without a public IP to access Google APIs (BigQuery, Cloud Storage, etc.) without going out to the internet. |
GCP's load balancer is global and anycast. A single public IP distributes traffic to backends in multiple regions simultaneously. There are no load balancer clusters — Google manages it at global scale.
Global External HTTPS LB
Distributes HTTP/HTTPS traffic globally. Support for Cloud CDN, Cloud Armor, URL routing, and backends in multiple regions.
Use: Global web apps, public APIs with users worldwide.
Regional External TCP/UDP LB
Balances TCP/UDP traffic within a region. High performance for non-HTTP protocols.
Use: Games, streaming, applications using proprietary protocols.
Internal Load Balancer
Balances private traffic within the VPC. Doesn't expose services to the internet.
Use: Internal microservices, databases behind a service layer.
Network Load Balancer (NLB)
Layer 4 (TCP/UDP/SSL), preserves the client IP. Useful when you need to see the original IP.
Use: Cases where source IP preservation is required, gaming servers, VPN endpoints.
Cloud CDN
Content Delivery Network integrated with Cloud Load Balancing. Caches static content at Google's edge PoPs (Points of Presence) closest to the user.
Cloud DNS
Managed DNS with 100% availability SLA. Low SLA: <4ms average latency. Supports public and private DNS (for internal resolution within VPCs).
| Service | What it does | When to use |
|---|---|---|
| Cloud VPN | Encrypted IPsec tunnel between your on-premises network and the GCP VPC over the internet. Up to 3Gbps per tunnel. | Low-cost secure connectivity. Doesn't require dedicated hardware. |
| Cloud Interconnect | Dedicated high-speed physical connection (10-200Gbps) between your datacenter and GCP. Very low latency. | Workloads that move large volumes of data (backup, replication, mass migration). |
| Partner Interconnect | Same as Interconnect but through a partner provider. No need for a direct connection to a Google PoP. | When you don't have physical access to a Google datacenter but need more than VPN. |
| Cross-Cloud Interconnect | Dedicated connection between GCP and AWS/Azure for multi-cloud architectures. | Moving data between clouds without going over the public internet. |
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A global company has its web application deployed on backends in us-central1 and europe-west1. They want users on each continent to be automatically routed to the nearest backend, with a single public IP and HTTPS support. Which GCP solution should they use?
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