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Hello Fellows! I would like ask for some help regarding this scenario (see figure below). Basically I would like the LAN host to be able to access both ISPs.For that ...
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  1. #1
    Just Joined!
    Join Date
    Aug 2007
    Posts
    4

    ISP selection in a multihomed linux box


    Hello Fellows!

    I would like ask for some help regarding this scenario (see figure below).

    Basically I would like the LAN host to be able to access both ISPs.For that I would like
    to set the LAN GATEWAY to mark the traffic destined to ISP1 with 1 and the traffic going to ISP2 with
    a MARK 2.

    Im using a single cable between the LAN GATEWAY and the multihomed box and vlans so ISP1 traffic should
    flow through vlan101 and ISP2 traffic through vlan102.

    What i dont know is what kind of discriminant I could use to tell the LAN GATEWAY (by using iptables) that the traffic is either targeted to ISP1 or 2.

    Im using iptables 1.3.6 and Ubuntu 7.09. NAT is also working as i can reach both isps gateways

    1.1.1.1/24 2.2.2.1/24
    ISP1 ISP2
    | |
    |eth1=1.1.1.2/24 |eth2=2.2.2.2/24
    ---------------------------------
    | MULTIHOMED |
    | LINUX BOX |
    ---------------------------------eth0
    | .1 |.1
    vlan101 vlan102
    192.168.101.0/24 192.168.102.0/24
    | |
    |.2 |.2
    --------------------------------eth0
    | LAN GATEWAY |
    | LINUX |
    | |
    --------------------------------
    |eth1 192.168.0.1
    |
    |
    LAN HOST 192.168.0.2

    Thanks for any help... I could clarify further if i wasnt clear enough..

    ant

  2. #2
    Just Joined!
    Join Date
    Sep 2007
    Posts
    4
    hi,

    i dont exactly know whether this rule going to work :
    simply drop vlan102 outgoing to isp1 and vice versa in OUTPUT chain

    or
    you can SNAT vlan1 to isp1 interface and vice versa.

    HTH.

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