Network & Infrastructure / IPv6, TCP & Transport Engineering
IPv6 duplicate address detection after VM cloning
A cloned virtual machine fails to activate its expected IPv6 address. Its interface is up, but duplicate address detection reports a conflict or the address remains tentative.
Environment and inputs: Dual-stack routed networks and transport endpoints; validate the complete path and the active operating-system version. Diagnostic/design example; not tested on production equipment.
Collect the evidence
Record the tentative address, neighbor solicitations and advertisements, virtual NIC identity and cloning procedure. Distinguish a real duplicate from a packet-reflection issue in the virtual switching path.
Explain the result
DAD checks ownership on the local link before normal use. Reused addressing or reflected probes can prevent activation; disabling DAD would hide the evidence instead of proving uniqueness.
Plan the fix
Correct address generation or the Layer-2 reflection problem at its source. Preserve the intended uniqueness mechanism and verify that orchestration creates distinct identities when required.
Check the result and rollback
Provision a fresh test VM and confirm stable unique addressing and neighbor resolution. Revert the cloning change if it creates new identity conflicts or affects intended service anycast behavior.