Hi everybody,

I need to make a load balance between two WAN connections. I have found some information about it but i dont understand.

"Unlike other guides on this topic I will use a real example - the configuration on our internal network. So to begin with here are the basic data for my network:

#IP address of external interfaces. This is not the gateway address.
IP1=192.168.1.10
IP2=192.168.0.10

#Gateway IP addresses. This is the first (hop) gateway, could be your router IP
#address if it has been configured as the gateway
GW1=192.168.1.1
GW2=192.168.0.1

# Relative weights of routes. Keep this to a low integer value. I am using 4
# for TATA connection because it is 4 times faster
W1=1
W2=4

# Broadband providers name; use your own names here.
NAME1=bsnl
NAME2=tata

You must change the example below to use your own IP addresses and other details. Even with that inconvenience a real example is much easier to understand than examples with complex notations. The example given below is copy-pasted from our intranet configuration. It works perfectly as advertised.

Note: In this step fail-over is not addressed. It is provided later with a script which runs on startup.

First you need to create two (or more) routes in the routing table ( /etc/iproute2/rt_tables ). Open the file and make changes similar to what is show below. I added the following for my two connections:

1 bsnl
2 tata


To add a default load balancing route for our outgoing traffic using our dual internet connections (ADSL broadband connections from BSNL & Tata Indicom) here are the lines I included in rc.local file:

ip route add 192.168.1.0/24 dev eth1 src 192.168.1.10 table bsnl
ip route add default via 192.168.1.1 table bsnl
ip route add 192.168.0.0/24 dev eth2 src 192.168.0.10 table tata
ip route add default via 192.168.0.1 table tata
ip rule add from 192.168.1.10 table bsnl
ip rule add from 192.168.0.10 table tata
ip route add default scope global nexthop via 192.168.1.1 dev eth1 weight 1 nexthop via 192.168.0.1 dev eth2 weight 4


Adding them to rc.local ensures that they are execute automatically on startup. You can also run them manually from the command line.

This completes the load balancing part. Let's now see how we can achieve fail-over so the routes are automatically changed when one or more connections are down and then changed again when one or more more connections come back up again. To do this magic I used a script.

"
I dont understand what are they doing with the routing table. Global scope, link scope..

I will appreciate your help.

thanks in advance