Backup network segmentation is one of the cheapest ways to reduce ransomware blast radius, but it is often designed too late: after the backup repository already lives in the same flat VLAN as users, servers and admin workstations. The result is predictable. If an attacker gets domain credentials or lands on a privileged desktop, the backup platform becomes just another target to encrypt, delete or silently corrupt.
This practical design guide shows a small-office, branch or small data center pattern that separates backup management, backup data and immutable/offline copies. It is intentionally vendor-neutral and fits firewalls, L3 switches or SD-WAN edges. For broader design context, see the Start Here networking topics, Data Center Networking and Resources pages.
