To enable aggregated Ethernet (AE) interfaces on a Junos device, you must first specify the total number of AE interfaces the device will support. This is a system-wide, chassis-level setting configured under the [edit chassis] hierarchy using the aggregated-devices ethernet device-count statement. This command allocates the specified number of AE interfaces (e.g., ae0, ae1, etc.) for subsequent configuration under the [edit interfaces] hierarchy. Without this initial declaration, AE interfaces cannot be configured or used.

A. [edit switch-options]: This hierarchy is used for configuring Layer 2 switching features like VLANs or storm control, not for defining the number of available aggregated Ethernet interfaces.

B. [edit system]: This hierarchy is for system-wide operational parameters such as hostname, login settings, and system services, not for hardware-related interface allocation.

C. [edit interfaces]: While individual AE interfaces (like ae0) are configured here, the ability to create them must first be enabled under the [edit chassis] hierarchy.

1. Juniper Networks Documentation

"Aggregated Ethernet Interfaces Configuration Guide for Switches

" Configuring Aggregated Ethernet Interfaces. The guide states

"To configure an aggregated Ethernet interface

you include the aggregated-devices statement at the [edit chassis] hierarchy level..."

2. Juniper Networks Documentation

"Junos OS Administration Library for Routing Devices

" aggregated-devices. This document specifies that the aggregated-devices statement is configured at the [edit chassis] hierarchy level to set the number of logical devices.