Aviz Networks outlines OpenStack live migration in SONiC
Aviz Networks describes how OpenStack live migration can move a running virtual machine between hosts with limited interruption when the underlying EVPN-VXLAN fabric preserves Layer 2 reachability, gateway consistency, and MAC/IP mobility. The post is aimed at teams that already operate this environment and need to validate fabric behavior before production use.
Research Overview
The article focuses on the interaction between OpenStack compute, virtual networking, and SONiC-based EVPN-VXLAN switching during live migration. It states that the VM, its IP address, and its gateway must remain reachable while the network updates the VM’s location.
It also says the migration process depends on coordination among Nova, Neutron with OVS or OVN, and the physical EVPN fabric. The goal is to move traffic from the source host to the destination host without packet loss.
Key Findings
The post says seamless migration requires consistent EVPN Instance and VXLAN Network Identifier membership across source and destination leaf switches. It also requires matching VLAN-to-VNI mappings so the VM remains in the same Layer 2 broadcast domain after the move.
Other requirements include anycast gateway consistency, host-independent Layer 2 reachability, and support for VXLAN encapsulation and decapsulation. The article says the underlay MTU must be large enough to handle VXLAN overhead.
Technical Breakdown
The migration sequence begins when Nova starts the move and copies memory pages to the destination compute node. Neutron then configures the destination port, and OVS or OVN binds the virtual interface to the tenant VNI.
Next, the destination leaf learns the VM MAC address and advertises an EVPN Type-2 route update. The article says Neutron or OVS then sends a gratuitous ARP or unsolicited neighbor advertisement to refresh ARP and neighbor tables before traffic is redirected to the new VTEP.
Fabric validation
The post says Aviz Networks’ Fabric Test Automation Suite is used to test SONiC fabrics before production. It describes tests for basic live migration, migration under CPU and memory load, concurrent migrations, failure handling, and EVPN-VXLAN control-plane behavior.
The expected outcomes include low or no packet loss, continued VM reachability, stable control-plane behavior, and no blackholing of traffic. The article says the suite is used to validate MAC mobility, gateway persistence, and migration traffic on SONiC fabrics.
Operational Impact
The article frames live migration as a network and systems integration exercise rather than only a compute function. It says operators need stable routing, control-plane convergence, and consistent overlay behavior to keep VM traffic moving during migration.
To help teams map the process, the post compares OpenStack live migration with VMware vMotion, block migration with Storage vMotion, OpenStack Controller with vCenter, and KVM with ESXi. It says this comparison is meant to make migration behavior easier to interpret for teams familiar with VMware environments.
Aviz Networks says teams running or planning EVPN-VXLAN-based OpenStack should validate production traffic behavior before migration. The company presents FTAS as a way to test the fabric for MAC mobility, gateway persistence, and migration traffic.
This Blog Signals brief is a fact-based summary of the vendor blog and focuses on the migration requirements, sequence, and validation methods described by Aviz Networks.