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Hi,

I am trying to create a small topology as follows:

VM-AEnd <-----> VM-ISys <--------> VM-ZEnd

At VM-AEnd
eth0: NATed
eth1: Internal Network 1

At VM-ISys
eth0: NATed
eth1: Internal Network 1
eth2: Internet Network 2

At VM-ZEnd
eth0: NATed
eth1: Internal Network 2

Now at Guest Machine --> VM-ISys, I wanted to do ethernet bridging of eth1 & eth2 interface so that I expand the broadcast domain of Internal Network 1 into Internal Network 2 and vice versa.

I do not want to put the VM into single hostonly network, and do not want to assume about L3 network configurations. Hence I wanted simple ethernet bridging at VM-ISys so that I can create a test network topology in which I can play around.

At VM-Isys -->
(a) brctl of eth1 & eth2 does not work. The moment I add br0 with eth1 & eth2, the connectivity between VM-AEnd & VM-ISys is lost (with typical IPv4 configuration through ping). Same happens between VM-ZEnd and VM-ISys.
(b) If I create tap devices in host and attach them to the VM-AEnd, ZEnd & ISys, then will brctl based briding at the host give the above desired behaviour.
i.e. traffic in Internal Network 1 and Internal Network 2 gets bridged only at VM-ISys and not elsewhere.

Any suggestion how I can achieve the same ?

Regards,
Mahesh Babu

mahesh babu wrote:At VM-Isys -->
(a) brctl of eth1 & eth2 does not work. The moment I add br0 with eth1 & eth2, the connectivity between VM-AEnd & VM-ISys is lost (with typical IPv4 configuration through ping). Same happens between VM-ZEnd and VM-ISys.

That's exactly the behaviour of bridged interfaces.

mahesh babu wrote: (b) If I create tap devices in host and attach them to the VM-AEnd, ZEnd & ISys, then will brctl based briding at the host give the above desired behaviour.
i.e. traffic in Internal Network 1 and Internal Network 2 gets bridged only at VM-ISys and not elsewhere.

As expected aswell.

mahesh babu wrote:Any suggestion how I can achieve the same ?

I don't understand why you want to use two network if you want to keep a single broadcast domain - you're basically going against what you want, and then add another layer to come back to it.

None of your issues are Virtualbox related, only network related. My best advice would to look for local network support, as this forum is for Virtualbox issues.