Networking Landscape in Juniper OS

Ever wondered how your traffic effortessly finds its way from point A to Point B ? Lets take a look at the inner workings of the control and forwarding planes working in harmony to keep your data on the move.

In this blog post we are taking a no-nonsense path to understanding the innner workings of Juniper’s control and forwarding planes breaking the technical details down bit by bit, taking control once and for all.

Control Plane

The control plane consists of the Routing Engine (RE) which has the responsibility of handling routing protocol processes, chassis components, system management and user access to the router. It is important to note that the RE manages the Routing Table (RT) and from it then dervives the Forwarding Table (FT).

Forwarding Plane

The forwarding plane consists of the Packet Forwarding Engine (PFE). The PFE makes use of the FT to forward transit traffic through the device. Any traffic which does not match to the FT or requires further processing will be forwarded to the RE.

Routing Engine

The Routing Engine takes on the task of running the Junos operating system and it consists of all processes and PCI which the OS runs on.

The Routing Engine runs various protocol and management software processes that reside inside a protected memory environment. The Routing Engine maintains the routing tables, bridging table, and primary forwarding table.

The RE is connnected to the PFE with a rate limited internal link with the value being set and cannot be changed by the user (hard-coded). This is done to prevent DoS attacks.

Features that can be found on the Routing Engine includes:

  1. The processing of routing protocol packets
  2. Modular Software
  3. IP functionality
  4. Scalability
  5. Storage and change management
  6. Accounting and Alarms

Packet Forwarding Engine

The main objective of the packet forwarding engine (pfe) is to handle and forward transit traffic to the correct destination in the fastest way possible.

On the packet forwarding engine 3 components can be found made with Application Specific Integrated Circuits (ASICs) to allow for Layer 2 and Layer 3 packet switching, route lookups and packet forwarding.

These components include:

  • Switching control board
  • Physical Interface Card (PIC)
  • Flexible PIC Concentrator (FPC)

Since the architecture seperates control operations such as protocol updates and system management from frame and packet forwarding, the switch can deliver a high level of performance and reliable operation. The FT updates takes place without interrupting the router’s forwarding.

One could say that the RE is the brains and the PFE does as it is told.

For more information head over to Juniper Networks.

Thank you for taking the time to read this 😀