Two Eth Interfaces for same subnet?

Unanswered Question
Apr 2nd, 2007
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Current Setup:

Our network is comprised of multiple sites around the city. Each site is assigned a specific subnet. For example: Site A ? 10.1.X.X ; Site B ? 10.2.X.X ; Site C ? 10.3.X.X

The sites all tie back in to a central site at it?s router.

Beginning of Dilemma:

Site E has two ways of connecting back to the central site, through wireless bridges or a dry loop (naked DSL). However, only one of these methods can be used at a time. What I?m trying to do is get both of the links up at the same time so that we have a fast connection via the wireless bridges, and a reliable line with the dry loop if the wireless goes down.


I?m able to get both the wireless bridges and the dry loop up, but I cannot have them both plugged into the router at the central location. Right now, one of the Ethernet interfaces is assigned the IP of It will not allow another Ethernet interface to be assigned an address of 10.5.X.X for the other line.

I tried creating a bridge group for the two interfaces and assigning it a single address which seemed to work out for a second, but there was a really slow transfer rate.

My Question:

Is the bridge group the only method to go about doing what I?m trying to accomplish, or is there a better way?

Thank you in advance,


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recon3344 Tue, 04/03/2007 - 12:25
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The other thing I was wondering is if spanning-tree would resolve this issue?

paolo bevilacqua Tue, 04/03/2007 - 16:02
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You can user BVI and STP to have two interfaces in the same subnet, but one port will go blocking. This ised sometime for redundacy when connected to two switches.

In you case, what prevents you from using regular routing? You can then use PBR for sending some traffic to one interface or another.

Hope this helps, if so please rate post!


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