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Tim Long
Asked: 2010-05-14 04:27:51 +0800 CST

Is there a sensible way of 'teaming' two ADSL connections?

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I work in an office complex that has two seperate ADSL connections, which they use to provide two seperate networks (actually both the ADSL routers go into a Cisco managed switch with two VLANs, one for each ADSL connection).

Circumstances have changed so that 95% of the users are all on one ADSL connection. It would be great if there were a way to join together both connections to emulate a single connection at double the speed, but the ISP doesn't support bonding.

So, is there a sensible way to take two completely seperate ADSL lines and use them to provide a single internet gateway?

load-balancing adsl bonding

5 Answers

  1. Best Answer

    There are numerous appliances and routers (e.g. Zyxel P-663H) which will support two internet connections and balance outbound sessions across the two links.

    For IP routing reasons this almost always involves NAT, although if you're already using NAT that shouldn't be an issue for you.

    Balancing inbound traffic resiliently is a lot harder, since you have to publish an IP address for each inbound service, and those IPs can only ever be associated with one link.

    The alternative is to swap to an ISP who can bond lines so that each line is properly bonded.

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  2. You can use loadbalancing. When new connection appears, loadbalancer decides which ADSL line will use. Basic algorithm for choosing line switches between them for each connection. For example first connection goes thru line A, second thru line B, third thru line A, etc.

    This algorithm needs support only on your site - your router. For example Mikrotik or any linux based machine.

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  3. With linux is pretty easy ( http://lartc.org/howto/lartc.rpdb.multiple-links.html )

    If you want you could use pfsense for a graphical interface gateway.

    Or debian + shorewall ;)

    Pier

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  4. Ecessa makes some reasomnably priced load balacer/failover devices. Worth a look

    Ecessa

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  5. It would definitely be worth considering a fully bonded connection. It would obviously mean changing public IP etc, but your new IP would be spread across the two connections, not dependant on either line seperately.

    And if you went for a bonded provider that does it without using MLPPP then you don't have to worry about linux boxes or unsupported equipment in the future.

    It will work on any BT line that can have broadband. Are there any more specific reasons why you wouldnt want to move ISP?

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