How to Determine the order in which interface names are assigned to ESXi

In VMware ESXi, network interfaces and other devices are assigned aliases like vmnicN for network interfaces and vmhbaN for storage adapters. These aliases are important because they ensure consistent device management, especially during reboots.

However, after installation, the system assigns aliases dynamically, which may not always match your preferred naming conventions. You may want to configure or customize these aliases to align with your infrastructure needs.

This blog post will guide you through managing network interface aliases using the localcli tool in ESXi, which allows you to assign and store both PCI and logical aliases for devices.

Why Use Aliases?

Using aliases in ESXi helps simplify network and storage management. The aliases like vmnic0, vmnic1, and so on, correspond to physical network interfaces and are used to identify and reference network devices. By assigning custom aliases, you can make device identification more intuitive and manageable, especially in large-scale environments.

Step-by-Step Example: Managing Network Interface Aliases

Here’s how you can assign PCI and logical aliases to network interfaces using localcli.

1. Assign a PCI Alias to a Network Interface

First, you will assign an alias to a network interface using its PCI address. The PCI address uniquely identifies the physical location of the device on the system.

Command:

localcli --plugin-dir /usr/lib/vmware/esxcli/int/ deviceInternal alias store --bus-type pci --alias vmnic0 --bus-address p0000:12:00.3

Breakdown:

• localcli: ESXi’s local CLI tool for managing local system settings.
• --plugin-dir /usr/lib/vmware/esxcli/int/: Directory where ESXi CLI plugins are located.
• deviceInternal alias store: Command to store a device alias.
• --bus-type pci: Specifies that the bus type is PCI (i.e., it’s a physical device).
• --alias vmnic0: The alias you are assigning to the device.
• --bus-address p0000:12:00.3: The PCI bus address of the network interface (this uniquely identifies the physical location of the device on the server).

Example Output:

After running the command, you’ve successfully assigned the alias vmnic0 to the network interface with the PCI address p0000:12:00.3.

2. Assign a Logical Alias to the Same Network Interface

Next, you may want to assign a logical alias to the same network interface. Logical aliases provide a more abstract way to reference devices, which can be useful for high-level device management and abstraction.

Command:

localcli --plugin-dir /usr/lib/vmware/esxcli/int/ deviceInternal alias store --bus-type logical --alias vmnic0 --bus-address "pci#s00000001:09.02#0"

Breakdown:

• localcli: Used to execute commands locally on the ESXi host.
• --plugin-dir /usr/lib/vmware/esxcli/int/: Directory for ESXi CLI plugins.
• deviceInternal alias store: Command to store an alias for the device.
• --bus-type logical: Specifies the alias is for a logical device, rather than a physical PCI device.
• --alias vmnic0: The alias name for the logical device.
• --bus-address "pci#s00000001:09.02#0": A logical bus address in a different format, representing the network interface in a more abstract way.

Example Output:

This command assigns the alias vmnic0 to the network interface using the logical bus address "pci#s00000001:09.02#0". This logical address abstracts the device reference, allowing you to manage the network interface without directly tying it to a physical PCI location.

Verifying the Alias Assignments

To confirm that the alias assignments have been applied correctly, you can use the following command to list all network interfaces and their aliases:

codeesxcli system network nic list

This will display a list of network interfaces, showing both their PCI and logical aliases (if applicable).

Example Output:

Name    PCI Device   Driver   Link Status   MTU   RX Packets   TX Packets
------  -----------  -------  ------------  ----  -----------  -----------
vmnic0  0000:12:00.3  vmxnet3  Up            1500  1023404      2043409
vmnic1  0000:13:00.1  vmxnet3  Up            1500  45324        3435

Here, vmnic0 corresponds to the network interface at PCI address 0000:12:00.3.

Why This Matters

Using custom aliases ensures that your network interfaces and storage adapters are consistently named, which is particularly useful in large, complex environments where multiple physical devices may be managed. These alias assignments also help to:

• Avoid conflicts when reboots or hardware changes occur.
• Maintain a clear naming convention across your network interfaces and storage devices.
• Simplify the management of devices, especially in environments with many virtual machines and storage configurations.