Bubble networks are used in test-and-development labs and disaster recovery tests. Any group of VMs separated from the physical network on a private vSwitch can be called a bubble network. VMs on multiple hosts in a cluster can share a bubble network if a distributed virtual switch is used to connect them.
Because VMs in a bubble network do not use network interface cards (NICs), virtual and physical machines on the physical network do not register their existence. During a VM failover test, DR management tools such as VMware Site Recovery Manager, Veeam Backup & Replication and Zerto Virtual Replication power up recovery-site VMs in the test bubble network while production VMs are still operating. Without the isolated bubble network, duplicate IP addresses and host names would disable or corrupt the active infrastructure.