A VNI (Virtual Network Interface) is Versa’s naming scheme for the physical ports on a VOS appliance, written as vni-slot/port – for example, vni-0/0. It maps each Ethernet, SFP, SFP+, SFP28, or QSFP28 port to the logical interface Director, Concerto, and the CLI reference in configuration. One caution up front: in VXLAN contexts the same acronym expands to VXLAN Network Identifier – the 24-bit overlay segment ID, an unrelated concept covered under VXLAN. This page is about the interface naming scheme.
Key takeaways
- VNI names map physical ports to logical interfaces (vni-slot/port).
- Each VNI corresponds to one Ethernet, SFP, SFP+, SFP28, or QSFP28 port.
- Port count and supported optics per VNI are fixed by appliance model.
- Reinserting or changing an SFP requires disabling and re-enabling its VNI.
- VNI subinterfaces join bridge domains, networks, and routing instances.
On this page: Why it mattersHow it worksTypesVNI & VersaFAQ
Why is a VNI important?
A VOS appliance can range from a two-port branch box to a data-center-class chassis with dozens of 100-Gigabit ports, yet Director, Concerto, and the CLI need one consistent way to address “this port” regardless of model. VNI naming supplies that: vni-0/0 addresses the same logical slot/port position on a small branch appliance and a high-end aggregation chassis. The identifier is portable; the port behind it is not – connector, supported optics, and maximum speed are model-specific (see the FAQ below).
That consistency makes templates portable and zero-touch provisioning practical. A template built once can reference vni-0/0 as a WAN uplink and apply unchanged across a fleet of mixed models, because it targets the logical VNI, not a vendor-specific driver name – though each model still determines that port’s physical media, optics, and speed, so hardware planning stays per-model even when the configuration is fleet-wide. It also gives support engineers a stable troubleshooting vocabulary: an alert naming vni-0/2 points to one exact physical port, no lookup required.
What is a VNI?
Each VNI number identifies exactly one physical port: the format is vni-slot/port, so vni-0/0 is slot 0, port 0. The range of VNI numbers, and which optics each accepts, is fixed per model, not administrator-assigned. On a CSG1300, vni-0/0 and vni-0/1 are copper ports on an Intel X550T controller, vni-0/2 and vni-0/3 are SFP+ fiber ports on an Intel X710 controller, and vni-0/12 through vni-0/15 sit on a second SFP+ bank running an Intel X550EM controller – three chips, three port behaviors, one naming scheme.
Larger chassis extend the pattern to higher speeds: CSG5000 series appliances expose VNI ports accepting SFP, SFP+, SFP28, and QSFP28 transceivers for 1- through 100-Gigabit Ethernet, numbered separately from the chassis’s other Ethernet (enet-x) ports. After inserting an SFP or changing its speed, the VNI interface must be disabled and re-enabled before VOS recognizes the change.
Types of VNI
VNI ports fall into tiers by speed and medium, and which tiers exist depends on the appliance model. 1-Gigabit ports take copper RJ45 or short/long-wavelength SFP optics. 10-Gigabit SFP+ ports add short- and long-reach optics for branch uplinks and aggregation. 25-Gigabit SFP28 ports, on higher-end models such as the CSG5000 series, use the same connector family as SFP+ at 2.5 times the throughput. 100-Gigabit QSFP28 ports, including direct-attach copper cable options, appear on larger chassis for data-center and aggregation roles.
Which tiers a VNI number supports is fixed by its underlying controller, not configurable: on a CSG1300, vni-0/0 and vni-0/1 run only 1/10-Gigabit copper, while vni-0/2 and vni-0/3 run 1/10-Gigabit fiber – two adjacent VNI numbers, two capabilities, because they terminate on different controller silicon.
VNI & Versa
VNI is the identifier every higher configuration layer in VOS builds on. Director, Concerto, and the CLI all configure interfaces by vni-x name – assigning an IP address, binding it to a network, or making it a member of a bridge domain by matching VLAN ID. Interfaces sharing a routing instance group into a network, and a VNI subinterface’s VLAN tag ties it into a bridge domain for Layer 2 switching.
Because supported optics vary by model, Versa publishes a validated-transceiver guide per series: the CSG1000 series guide and CSG5000 series guide list which SFP, SFP+, SFP28, or QSFP28 part numbers are qualified for that model’s VNI ports. The CSG1000 series hardware guide documents the port-to-VNI mapping those guides assume.
Frequently asked questions
What does the number in a VNI name like vni-0/0 mean?
The format is vni-slot/port. The first number identifies the physical slot – typically 0 for built-in ports – and the second identifies the port within that slot. Each combination maps to exactly one physical Ethernet, SFP, SFP+, SFP28, or QSFP28 port on the chassis.
Can I choose which optics a given VNI port supports?
No. Supported optics are fixed by the Ethernet controller wired to that VNI number, which differs by appliance model and sometimes by port range on the same chassis. Consult the validated-transceiver guide for your model before ordering optics in bulk.
Why do I need to disable and re-enable a VNI after changing an SFP?
VOS reads certain optical parameters, such as link speed, only when a VNI interface initializes. Changing an SFP or its speed afterward leaves the interface running against stale settings, so a disable/re-enable cycle forces VOS to reread the transceiver and apply the change.
Are VNI ports the same as Ethernet (enet) ports on a VOS appliance?
No. VNI and enet are separate numbering ranges on the same chassis. On a CSG5000 series appliance, both vni- and enet-numbered ports accept SFP or QSFP optics, but they sit in distinct address spaces – vni-0/0 and enet-0/4 are different physical ports, not aliases.
Does the same VNI number mean the same thing on every VOS appliance model?
No. vni-0/0 exists on nearly every model, but its connector, supported optics, and maximum speed depend on that model’s hardware – a CSG1300’s vni-0/0 is a fixed copper port, while a CSG5000 series vni-0/0 is a fiber port supporting up to 25-Gigabit optics.
More on VNI
If you want to learn more, these are sources we trust.
| Versa Networks: products | Versa Networks: secure SD-WAN | Versa Academy |
|---|---|---|
| The vendor’s product pages, covering the VOS appliance families whose physical ports VNI naming addresses. | The Secure SD-WAN service that traffic on VNI-numbered interfaces carries, as packaged by the vendor. | Training and labs that configure VOS interfaces hands-on, including VNI-numbered ports on real hardware. |
Related terms
If you’re reading about VNI, these are worth looking at next.
| Appliance | Bridge Domain | Network |
|---|---|---|
| The physical or virtual VOS device whose ports VNI naming identifies, from branch box to gateway node. | The Layer 2 broadcast domain a VNI subinterface joins by matching VLAN ID, sharing its MAC forwarding table. | The VOS object that groups interfaces, including VNI ports, sharing a routing instance; each belongs to one. |