VPC Networking

A Virtual Private Cloud (VPC) is a logically isolated network on IBM Cloud where you deploy your compute, storage, and database resources. VPC networking gives you full control over IP addressing, subnets, routing, and security.

---

What is a VPC?

A VPC provides:

• Isolation — your resources are logically separated from other tenants
• Control — you define the IP address ranges, subnets, and routing
• Security — use security groups and ACLs to control traffic
• Scalability — spans multiple availability zones within a region

Every VPC exists within a single IBM Cloud region.

---

VPC Components

Address Prefixes

When creating a VPC, you define address prefixes (CIDR blocks) for each zone:

Zone	Address Prefix	Usable IPs
us-south-1	10.240.0.0/18	~16,000
us-south-2	10.240.64.0/18	~16,000
us-south-3	10.240.128.0/18	~16,000

Subnets

A subnet is a range of IP addresses within a zone:

• Each subnet belongs to a single availability zone
• Has its own CIDR block (subset of the address prefix)
• Attached to a network ACL for traffic control