Dual ISP bandwidth aggregation

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Apr 3rd, 2008
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Please provide me a solution for this,

Is it possible to aggregate dual isp link bandwidth. My customer is planning to take 2 connections from different ISP's. And he would like to aggregate both ISP's bandwidth. Eg:- From each ISP he is getting 2 mbps bandwidth(ISP 1 = 2mbps, ISP 2 = 2mbps). So he want to get total 2+2 = 4 mbps. Is it possible to aggregate both link and get 4 mbps for incoming and outgoing? Is it possible in cisco routers? Please let me know about this ASAP.

Thanks in Advance.

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paolo bevilacqua Thu, 04/03/2008 - 08:06
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No, aggregating bandwidth for two isp is not possible neither with cisco routers neither with anything else.

What you can do is called load balancing, you're with cisco you can ask a more senior colleague to explain you the concept.

shridhar19 Thu, 04/17/2008 - 23:08
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I think you can use Multilink to aggregate bandwidth of both ISP's,which is available in Cisco routers.

Sushil Kumar Katre Mon, 04/21/2008 - 23:43
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First you need to tell us whether these are private circuits like leased lines or Internet Connectivity?

In any case you can't really aggregate the bandwidth an dget a pipe of 4 Mb. However if your cusrmers requirement is to utilize both the links then you can ahve two default routes configured on the router pointing to these two links and use both the links at a same eventually getting 4 Mbps. This holds true for LL connection.

If its Internet Connection, you can't really use both the links at the same time and do load sharing/ load balancing because of the way NAT is implemented on Cisco's router. However what you can do at max is have your LAN users divided in two groups, GROUP A users would always use ISP A and GROUP B would always use ISP B, however please note that there won't be any failover again because of the way NAT is implemented.

The work around is to have two routers conected to a switch and terminate one ISP link on each router and then you can use both the ISP links.

-> Sushil


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