Ctrl+Alt+Route

When you’re experimenting with routing in a homelab, you usually face one of two options: spin up vendor simulators that require heavy resources, or rely on static routes and hope it’s “good enough.”

But if you want something lightweight, open-source, and powerful enough to run real routing protocols, the FRRouting (FRR) Project is one of the best tools you can add to your environment.

FRR brings production-grade routing daemons to Linux and BSD systems. It supports all major dynamic routing protocols and fits perfectly into virtualized labs, container environments, and Linux-based routing platforms. Whether you’re testing BGP policies, building an underlay fabric, validating failover paths, or modeling service-provider concepts, FRR gives you a full control-plane with almost no overhead.

This post breaks down what FRRouting is, why it’s useful, and how to get started with a basic configuration.

What Is the FRRouting (FRR) Project?

FRRouting (FRR) is an open-source IP routing protocol suite built for Linux and BSD platforms. It provides the control-plane logic behind routing decisions, while the data-plane (packet forwarding) is handled by the operating system’s kernel or hardware.

According to the official documentation, FRR aims to provide a robust and scalable control-plane aligned with modern routing RFCs.
Reference: https://docs.frrouting.org/en/latest/about.html

Here are the key characteristics that define FRR:

Modular Architecture

FRR is designed around separate daemons for each routing protocol or function. Examples include:

• bgpd for Border Gateway Protocol
• ospfd and ospf6d for OSPFv2 and OSPFv3
• isisd for IS-IS
• ripd and ripngd for RIP and RIPng
• pimd for multicast
• zebra for kernel route management

All protocol daemons communicate through the Zebra daemon, which installs routes into the kernel and coordinates system-wide routing behavior.

This modular design keeps the suite stable, extensible, and efficient. If one daemon stops, others continue running. You also only enable what you need, reducing resource usage.

Real Routing Capability

FRR supports a long list of routing features and RFCs. This includes IPv6, VRFs, extensive BGP capabilities (communities, attributes, route-maps), OSPF areas, redistribution, and more.

It is used in production environments by ISPs, cloud platforms, and data centers, yet still lightweight enough to run on a Raspberry Pi or a small VM in your lab.

Strong Fit for Virtual and Lab Environments

FRR integrates extremely well with:

• VMware and KVM
• Proxmox
• Docker and Podman
• Linux network namespaces
• Container-based labs
• Virtualized routing fabrics

The project explicitly supports using FRR to build multi-router labs, even on small hardware. For homelab users, this flexibility is a major advantage.

Basic Setup: How to Start Using FRR

The installation and configuration process is simple, especially if you’re familiar with Linux.

Official documentation reference:
https://docs.frrouting.org/en/latest/setup.html
Below is a practical overview tailored to homelab and testing scenarios.

1. Install FRR

Most modern Linux distributions include FRR in their repository.

Example for Ubuntu:

sudo apt update
sudo apt install frr frr-pythontools

2. Enable the Routing Protocol Daemons

FRR does not start any routing protocols by default. You must enable them manually.

Edit the main daemon configuration file:

sudo nano /etc/frr/daemons

Enable the protocols you want:

zebra=yes
bgpd=yes
ospfd=no
pimd=no
vtysh_enable=yes

Notes:

• Zebra is required; it manages kernel routing tables.
• vtysh_enable=yes activates the unified CLI for configuration.
• Only enable what you need to keep your environment lean.

3. Start the FRR Service

Depending on the distribution, FRR may or may not automatically include a systemd service. If not, you can install the sample frr.service file provided in the project repository.

Once systemd is set up:

sudo systemctl daemon-reload
sudo systemctl start frr
sudo systemctl enable frr

Check service status:

sudo systemctl status frr

4. Use the vtysh CLI

FRR includes vtysh, an integrated command-line shell with syntax similar to Cisco IOS and other CLI-based routers.

Open the shell:

sudo vtysh

Examples inside vtysh:

frr# configure terminal
frr(config)# router bgp 65001
frr(config-router)# neighbor 10.1.1.2 remote-as 65002

This allows you to run commands such as:

• show ip bgp summary
• show ip ospf neighbor
• show running-config

5. (Optional) Use Network Namespaces for Multi-Router Labs

If you want multiple routers running on a single Linux host, FRR supports running isolated instances inside network namespaces.

For each namespace, modify /etc/frr/daemons:

watchfrr_options="--netns=<namespace>"

Then start FRR within that namespace.
This approach is can be very powerful for simulating complex network topologies without spinning up multiple VMs.

Why FRR Is Ideal for Homelab and Learning Environments

FRR is an excellent tool for both newcomers and experienced professionals because it allows realistic routing behavior in a flexible and inexpensive way.

You can use FRR to:

• Build BGP or OSPF topologies
• Test routing policies and failover
• Model IPv4/IPv6 dual-stack environments
• Work with VRFs, route redistribution, or MPLS-like scenarios
• Practice CCNA/CCNP-level routing concepts
• Test overlays or underlays
• Integrate routing into automation workflows
• Run multiple routers on one machine using namespaces

For anyone wanting to understand routing at a deeper level, FRR provides a complete and accessible toolset.

Summary

FRRouting is a powerful, open-source routing suite designed for Linux and BSD systems. It offers a modular architecture, supports all major routing protocols, and integrates seamlessly with virtualized and container-based environments.

By enabling only the daemons you need and using tools like vtysh and namespaces, you can build anything from a simple two-router lab to a multi-node routing fabric entirely on a single server.

If you’re exploring routing in your homelab, studying for a networking certification, or validating network designs, FRR is a tool worth learning and incorporating into your environment.