LB-Wan

Load Balancer WAN provide a mecanism to load balance multiple Internet ISP connections increasing connection reliability and bandwidth.

This first implementation is pure bash scripting.

How it works

LB-Wan use iproute2 Multiple Route Tables feature to segregate every WAN/ISP routes in a separate routing namespace.

Segregation is made by Virtual Routing and Forwarding (VRF).

Load Balancing routing is composed with active WAN/ISP instances in order to ensure reliable connections.

Prerequisites

At the moment LB-Wan relies on:

• A systemd GNU/Linux environment
• iptables Linux netfilter project
• ifupdown networking tools (netplan is coming, as well as NetworkManager)
• ISC DHCP Client

Installation

> git clone https://github.com/signal-09/lb-wan
> cd lb-wan
> aclocal && autoconf && automake --add-missing
> ./configure --prefix=/usr --sysconfdir=/etc --runstatedir=/run
> make
> sudo make install

Install the following dependencies:

> apt-get install isc-dhcp-client

Configuration

Networking

Suppose a Debian based router with 4 network cards:

                                            -- eth1 --- FTTH --
                                           /                   \
                               +----------+                     \
  192.168.0.254/24 --- eth0 ---|  Router  |--- eth2 --- FTTC ----+--> Internet
                               +----------+                     /
                                           \                   /
                                            -- eth3 --- FWA ---

The system network configuration file /etc/network/interfaces has the following content:

# The loopback network interface
auto lo
iface lo inet loopback

# Internal network
auto eth0
iface eth0 inet static
    address 192.168.0.254/24
    dns-nameservers 8.8.8.8 8.8.4.4

# FTTH internet provider
auto eth1
allow-hotplug eth1
iface eth1 inet dhcp

# FTTC internet provider
auto eth2
allow-hotplug eth2
iface eth2 inet dhcp

# FWA internet provider
auto eth3
allow-hotplug eth3
iface eth3 inet dhcp

Service

Create or edit the /etc/lb-wan.conf configuration file to reflect desired balanced connections:

# service	device	weight	ping-ips
FTTH		eth1	50	8.8.8.8
FTTC		eth2	30	8.8.8.8
FWA		eth3	20	8.8.8.8
LAN		eth0

The balanced connection will result in:

• 50% FTTH via eth1
• 30% FTTC via eth2
• 20% FWA via eth3

IP 8.8.8.8 is used as ping target to check connection readiness.

Reserved service name LAN identify the internal network. dns-nameservers from internal network will be used as balanced DNS servers.

Default values can be tuned by editing /etc/default/lb-wan file:

# Indicates how often to check the ping host for each ISP in seconds.
CHECK_INTERVAL=3

# How long ping are allowed to respond before consider unreachable.
PING_TIMEOUT=2

# Define the maximum packet losses required to declare a link up or down.
MAX_PACKET_LOSS=5

# Network manager (auto|ifupdown|netplan|manual)
NETWORKING=auto

# Comma or space separated DNS servers
#NAMESERVERS="0.0.0.0"

# Allow LB-Wan to manage iptables rules (e.g. FORWARD and NAT)
#IPTABLES=yes

# Setup IPv6 (EXPERIMENTAL)
#IPV6=no

Usage

Start the service:

> sudo systemctl start lbw-vrf
> sudo systemctl start lbw-balancer
OR
> sudo lbw service start

Routing table will change as follows:

> ip route show
default 
	nexthop via 172.16.1.1 dev eth1 weight 50
	nexthop via 172.16.2.1 dev eth2 weight 30
	nexthop via 172.16.3.1 dev eth3 weight 20
192.168.0.0/24 dev eth0 proto kernel scope link src 192.168.0.254 

For debugging purpose every service can be started in foreground (-f) or in debugging mode (-d):

> sudo lbw -f -t service start vrf
Nov 29 17:31:04 lbw-vrf[3791029]: net.ipv4.tcp_l3mdev_accept = 1
Nov 29 17:31:04 lbw-vrf[3791029]: net.ipv4.udp_l3mdev_accept = 1
Nov 29 17:31:04 lbw-vrf[3791029]: net.ipv4.ip_forward = 1
Nov 29 17:31:04 lbw-vrf[3791029]: Natting interface eth0 from 192.168.0.0/24
Nov 29 17:31:04 lbw-vrf[3791029]: Natting interface eth1 from 192.168.0.0/24
Nov 29 17:31:04 lbw-vrf[3791029]: Natting interface eth2 from 192.168.0.0/24
Nov 29 17:31:04 lbw-vrf[3791029]: Natting interface eth3 from 192.168.0.0/24
Nov 29 17:31:22 lbw-vrf[3791029]: Declaring FTTH UP
Nov 29 17:31:22 lbw-vrf[3791029]: Declaring FTTC UP
Nov 29 17:31:23 lbw-vrf[3791029]: Declaring FWA UP

> lbw -f -t service start balancer
Nov 29 17:59:00 lbw-balancer[3815641]: VRF service become available
Nov 29 17:59:00 lbw-balancer[3815641]: Set default route for IPv4 to nexthop via 172.16.1.1 dev eth1 weight 50 nexthop via 172.16.2.1 dev eth2 weight 30 nexthop via 172.16.3.1 dev eth3 weight 20

Stop the service:

> sudo systemctl stop lbw-balancer
> sudo systemctl stop lbw-vrf
OR
> sudo lbw service stop

Status

> sudo lbw status
Services:
- VRF[3866053]: active (enabled)
- Balancer[3866059]: active (enabled)
WANs:
- FTTH: UP (failures: 0, latency: 12.076)
- FTTC: UP (failures: 0, latency: 16.501)
- FWA: UP (failures: 0, latency: 21.229)

Suggestions

1. Do not use Modem IPs as DNS server: WAN/ISP with down link may not be able to resolve DNS names and may cause delay or timeout in name resolutions;