# [Networking] Bonding with 2 cablemodems (Open)

## ZaPa

Hi friends.

First, excuse my English.

I'm Spanish and I am using the google translator online.

I write this message to see if I can take a hand.

I'm thinking of doing with 2 bonding ADSL lines. (2 cable modem)

But I have some doubts about this.

The bonding I will apply for 2 cablemodems you will get the ip by dhcp.

If one bonding with 2 adsl lines, public ip What would you use?

What about gateway? Does the 1 or cable modem cable modem 2?

Can you make bonding with any ISP or the ISP must have a permit application or technology installed on your servers?

Thanks.

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## NeddySeagoon

ZaPa,

Your ISP will need to support bonding.

The process is to form a bond, then allocate a single IP to the bond. At the Linux end, the kernel works out how to share traffic between the members of the bond.

There may be more than two.

The next best thing you can do is load sharing between the two ADSL links.

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## ZaPa

Thanks for your response NeddySeagoon.

How can I tell if my ISP supports bonding?

If the cablemodems get ip by dhcp, an official on bonding?

What ip public use? the ip of 1 or cable modem cable modem 2?

Thanks for your interest.

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## Mad Merlin

 *ZaPa wrote:*   

> Thanks for your response NeddySeagoon.
> 
> How can I tell if my ISP supports bonding?
> 
> If the cablemodems get ip by dhcp, an official on bonding?
> ...

 

Call your ISP and ask them. Even if they do support bonding, they'll probably have to do some setup on their end before you can use it. However, if you don't already know that they support bonding, they probably don't.

As mentioned above, neither cable modem will have an IP address, only the bond device will have an IP address (which will be assigned via DHCP by your ISP).

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## ZaPa

Hello and thanks for you answers.

Of course the bonding device will have an ip you will get by dhcp?

But if you have 2 cablemodems connected.

"Would not get 2 ips for dhcp, that of cable modem 1 and the cablemodem2?

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## papahuhn

I don't think that any DSL provider will support bonding, but you could try multipath routing: http://lartc.org/howto/lartc.rpdb.multiple-links.html

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## ZaPa

Thanks for your answers.

"Routing multiple? What is it about? The result is the same as with bonding?

Is load balancing?

If so, this does not add the speeds of the 2 links, right?

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## papahuhn

No, it's not bonding. Bonding is at link layer while multipath routing is at network layer. Concretely, you can choose over which gateway IP packets will go out to the internet. Given the lartc howto below, one website (e.g. whatismyip.com) might tell you that you connect via provider P1, while another website (whatismyip.net) might tell you provider P2. So in a way, it will loadbalance multiple destinations.

However, in that configuration the same destination will be served by the same provider, so two connections to the same ftp server will go over the same link, while the other remains idle. There might be some another possibility to loadbalance outbound packets. If both providers do not filter SNATed packets you could use that to send packets over both ISPs in round robin manner, even to the same destination. Response packets would arrive over the same ISP, though - the one which provides the SNATed address.

However, I just read in wikipedia that there are ISPs in the UK which support ASDL bonding, so maybe spanish providers do it as well.

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## ZaPa

Mmmmmm I see ...

So if I can apply bonding?

"With load balancing them something?

Thanks.

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