Load Balancing with 2 ISP

Unanswered Question
Aug 19th, 2010


I really need help on making a configuration in a router 2600, I have 2 ISP (one Cantv and Movistar) one of them will give me a 2mbps of bandw with a static IP and the other will give me an DHCP IP address

With 1.5 mbps, and I have to make a load Balancing with this two different ISP.

I really need help, if you can help or any other college I really appreciated.


My e-mail is [email protected]

I have this problem too.
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Chetan Kumar Ress Thu, 08/19/2010 - 10:31

Hi Roberto

If you have two ISP and you are not running any routing protocol , Then also you can Load Balance with static route.

Simply you can put two static route i.e.

ip route ISP1

ip route ISP2

don't specify any AD in static route . So when you will see output of sh ip route , then you will see that

to reach any network ( Default nework ) you have two path .



Chetan Kumar


Jeremy Buck Thu, 08/19/2010 - 11:58

A couple of things to note about using the static route approach:

1) You will only transmit-load-balance, you will not receive-load-balance accross these links.

2) You won't really transmit load-balance unless you are NATing the traffic to the same source address/range.

3) If you use the statically assigned address as the source NAT over both links the ISP which assigns the DHCP address may deny your traffic outbound (if they are doing any rpf or anti-spoof check).

For this type of configuration you really need to secure public address space and coordinate with the ISP's to verify they will route back to it. Keep in mind that IP routing is "routing by rumor" or "routing by best path" and you can't control external routing, you can only influence it.

Chetan Kumar Ress Thu, 08/19/2010 - 15:07

Receive - load balance is not an issue , Because we don't need to control that one.

The path that will use for outgoing will be the same for incomming.( As we are not doing any routing to influence remote ISP )

We can have natting with source interface ( Static & DHCP ) using route map .



Chetan Kumar



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