comp.os.linux.networking

On Apr 1, 2:45 pm, Topi wrote:
> Hi,
>
> I have a Linux box with six ethernet adapters eth[0-5]. eth1 is for
> internet access and works as a dhcp client. The others are for lan
> cameras. I have a dhcp server running on eth{0,2,3,4,5} and it
> delivers addresses in 192.168.1.0/24 to all cameras. All camera
> interfaces have the same static ip 192.168.1.1.
>
> My problem is that I cannot find a way to set up routing tables so
> that traffic would get delivered to the correct interface, because all
> cameras are in the same subnet. Since traffic gets delivered to the
> interface of the first matching routing table entry, a camera in
> another device will never get the ip packets. Let's assume the
> situation is as follows:
>
> eth1: default route via 10.10.10.1
> eth0: connected to camera with ip 192.168.1.2
> eth2: connected to camera with ip 192.168.1.3
>
> Now, if I set up a static route to 192.168.1.0/24 through eth0,
> packets to 192.168.1.3 will be routed to eth0, and the camera in eth2
> will never see them. I could, of course, solve the problem by giving
> the cameras static IP addresses, but this isn't feasible in my
> application.
>
> Another problem that could not be solved with static addresses is with
> multicast traffic. The cameras are detected with UPnP, which builds on
> IP multicasts. The class D address space UPnP uses is 239.0.0.0/8.
> Now, whenever I send a UPnP message, it apparently goes down eth1,
> which is my default route. One camera starts working if I set up a
> static route to 239.0.0.0/8 through its interface, but the others
> won't, of course. My second question is: how do I make sure multicast
> messages will always get delivered to all the interfaces?
>
> I'm sure this is possible because even a simplest 15 EURO switch will do
> the trick. If I connect the cameras to such a box and attach it to my
> eth0, everything is fine. But how do I configure Linux to do the same
> thing with many network adapters?
>
> Any help is appreaciated.
> -Topi-

Use a bridge.
Bridge the camera's interfaces, it's what a layer 2 switch does. will
give you the same effect and will solve most (if not all) of your
problems.

read this http://www.faqs.org/docs/Linux-HOWTO/BRIDGE-STP-HOWTO.html

Have fun bridging :)