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I would like to know how to load balance two Business DLS links which have fixed IPs. I believe it would look something like this:

ip route add default scope global \
                     nexthop via gatewayDLS1 dev interface1 weight 1 \
                     nexthop via gatewayDLS2 dev interface2 weight 1

Is this be all I need in order to get multipath routing? Please, give me a more detailed answer if possible, thanks you.

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Are they both from the same provider and do you have real, public IPv4 addresses for things on your side of the gateway? I.e. are you running nat? – Flexo Jun 3 '11 at 15:48
@alan they are both from the same provider, I don't know if it is from the same dslam, but they have different fixed ipv4 address – user52883 Jun 3 '11 at 15:52
pfsense is better to do this job – User4283 Jun 3 '11 at 16:03
@User4283, citation needed. – Zoredache Jun 3 '11 at 23:10

As you already figured out, you just can work with a multipath route using equal weights. But the granularity of the balancing will be rather bad - all requests to the same destination IP address will go through the same link. You might want something more finely tunable here - which you can get by adding a couple of iptables rules - this howto from might give you a starting point.

For some background information there is a well-written section about multipath routing in Understanding Linux Network Internals (C.Benvenuti) which is even available online.

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Could you write a little bit more on why all the connection to the same destination go through the same link in such configuration? I'm just trying to figure this out, and even started a question here: – Mikhail Morfikov May 20 at 12:36

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