FRRouting is an open-source software suite for implementing routing protocols on operating systems such as Linux.

Installation

Install

sudo apt update
sudo apt install -y frr frr-pythontools
vtysh --version
sudo systemctl status frr
sudo systemctl enable --now frr

IP Forwarding

sysctl net.ipv4.ip_forward
sudo sysctl -w net.ipv4.ip_forward=1
echo 'net.ipv4.ip_forward=1' | sudo tee /etc/sysctl.d/99-routing.conf
sudo sysctl --system

FRR Command

sudo vtysh
show version

Configoration

‌Basic Conf

Enter global configuration mode.

configure terminal

Set the router hostname to R1.

hostname R1

Exit configuration mode and return to privileged EXEC mode.

end

Save the current configuration.

write memory

Config Scenario

Static Route

If both networks are directly connected to R1, Linux automatically recognizes the connected routes through the IP addresses assigned to its interfaces, so there is no need to configure static routes.

configure terminal
ip route 192.168.30.0/24 10.0.12.2
end
write memory

Architecture

Components

zebra: Manages communication between FRR and the operating system's routing table. bgpd: Implements the BGP protocol. ospfd: Implements the OSPF protocol for IPv4. staticd: Manages static routes. vtysh: Provides a unified command-line interface (CLI) for configuring and monitoring FRR.

‍‍‍```sh +----------------------+ | Network Admin | +----------+-----------+ | v +----------------------+ | vtysh | | CLI Configuration | +----------+-----------+ | +-------------+-------------+ | | | v v v +-----------+ +-----------+ +-----------+ | bgpd | | ospfd | | staticd | | BGP | | OSPF IPv4 | | Static | | | | | | Routes | +-----+-----+ +-----+-----+ +-----+-----+ | | | +-------------+-------------+ | v +----------------------+ | zebra | | Routing Management | +----------+-----------+ | v +----------------------+ | Linux Kernel | | Routing Table | | (FIB) | +----------+-----------+ | v +----------------------+ | Network Interfaces | | Packet Forwarding | +----------------------+

```