Mastering Junos' Flexible PIC Concentrators (FPCs) and Physical Interfaces

In this blog post, we will delve into the world of Juniper Networks' Junos operating system, focusing on Flexible PIC Concentrators (FPCs) and Physical Interfaces. This topic is crucial for those studying for the JNCIS-ENT certification, as understanding the hardware architecture and how it interacts with the Junos OS is fundamental to mastering Juniper networking.

What are FPCs?

In Juniper's hardware architecture, the Flexible PIC Concentrator (FPC) plays a significant role. The FPC is a component of Juniper's high-end devices, such as the MX series routers. It is responsible for housing the Physical Interface Cards (PICs) that provide the physical connection to various network media types.

Each FPC provides the necessary CPU and memory resources to run Junos OS and manage the PICs installed in it. The FPC communicates with the Routing Engine (RE), which controls the routing tables and routing protocol processes.

Understanding Physical Interfaces

Physical Interfaces in Junos are the actual hardware interfaces on the PICs. These interfaces can be Ethernet, Serial, ATM, etc., depending on the PIC. Each physical interface in Junos is identified by a unique name, such as ge-0/0/0, where 'ge' stands for Gigabit Ethernet, and the numbers represent the FPC slot, the PIC slot, and the port number, respectively.

Configuring FPCs and Physical Interfaces

In Junos, you can configure various settings for FPCs and Physical Interfaces. Let's look at an example of how to configure a physical interface.

user@router# set interfaces ge-0/0/0 unit 0 family inet address

In this command, 'set interfaces ge-0/0/0 unit 0 family inet address' is used to configure an IP address on the first Gigabit Ethernet interface on the router. The 'unit 0' refers to the logical unit or subinterface, and 'family inet' specifies that we are configuring an IPv4 address.

To verify the configuration, you can use the 'show interfaces ge-0/0/0' command:

user@router> show interfaces ge-0/0/0

This command will display the current configuration and status of the ge-0/0/0 interface.

While you can't directly configure an FPC in Junos, you can monitor its status and performance using various show commands. For example, the 'show chassis fpc' command displays the status of all FPCs in the system:

user@router> show chassis fpc


Understanding FPCs and Physical Interfaces in Junos is crucial for network engineers working on Juniper devices. These concepts are not only important for the JNCIS-ENT certification but also for real-world networking tasks. By mastering these, you can ensure efficient configuration and troubleshooting of Juniper network devices.

© Ben Jacobson.RSS