What physical interface is always a layer-3 interface on an Arista switch?

The dedicated management interface on an Arista switch (e.g., Management1) is fundamentally a Layer 3 interface by design. It is intended for out-of-band network management and operates within a separate management VRF (Virtual Routing and Forwarding) instance by default. To fulfill its function, it must be configured with an IP address, making it a routed port. Unlike front-panel Ethernet ports, which default to Layer 2 (switchport mode) and must be explicitly configured as Layer 3 (no switchport), the management interface is always treated as a Layer 3 entity for management traffic.

A. The USB1: port: This is a port for storage devices to perform tasks like software upgrades or file transfers, not a network interface.

B. The console: This is a serial port providing direct, out-of-band command-line access; it does not participate in network packet forwarding.

D. This question makes no sense: The question is valid because Arista switches have a specific physical interface that is always Layer 3 by default and design.

1. Arista Networks EOS Configuration Guide 4.31.1F, Section: Management Interfaces: "The management interface is a layer 3 interface that connects to the management network." This statement explicitly defines the interface's role at Layer 3.

2. Arista Networks EOS Configuration Guide 4.31.1F, Section: Management VRF: "The management VRF is the default VRF for the management port. The management port is a routed port that provides access to the switch for management purposes." This confirms its nature as a routed (Layer 3) port operating in a dedicated VRF.

3. Arista Networks EOS Configuration Guide 4.31.1F, Section: Configuring Ethernet Interfaces: "By default, Ethernet and port-channel interfaces are layer 2 interfaces. The no switchport command configures the interface as a layer 3 interface." This highlights the contrast between standard Ethernet ports (default L2) and the management port (inherently L3).