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[Xen-devel] VIF Interfaces not transparent to all ethernet protocols?

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Subject: [Xen-devel] VIF Interfaces not transparent to all ethernet protocols?
From: Armin Kemper <Armin.Kemper@xxxxxxx>
Date: Mon, 8 Nov 2004 20:28:57 +0000 (UTC)
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I'm new to XEN and trying to migrate from UserMode Linux, because its much 

After having some trouble messing around with devfs (I'm using gentoo...)
the VMs are booting fine.

My current UML Setup looks like this:

Main Machine:
linux-2.4.22-gentoo   (using SKAS patch)
2 ethernet interfaces
eth0 connected to LAN
eth1 connected to DSL-Modem

The UML-VM has 2 virtual Interfaces 
eth0 and eth1
apperaing as tap0 and tap1 on the main machine

the vm is connected to the lan via proxy-arp/routing (uml-stadard),
the tap1 Interface ist bridged to eth1 on the main machine.

The UML-VM is running the rp-pppoe driver on eth1 (tap1)

My XEN 2.0 setup:
what I tried to do is creating 2 bridges (one for each physical interface)
on the host, bridging the first VIF to the LAN and the second to the DSL-Modem.

when I start the rp-pppoe inside the vm, I can see the PPPoE packets appearing
on the eth1 Interface (using tcpdump -nei eth1 inside the vm), but they never 
arrive at the corresponding vif on the main machine (using tcpdump -nei vif1.1).

The other way, sending PPPoE packets, to the vif1.1 from the main machine works.
I can see them inside the VM, but the other direction seems to be blocked.

If I set an IP-address on the eth1 interface inside the vm, I can see IP/ARP 
packets to, but no PPPoE.

After searching the XEN Mailing lists and XEN Changlogs, I found that there has 
been a change in one of 1.x releases making changes to the handling of ethernet 
packets, but I can't find any similar code in the current release.
This was in ChangeSet@xxxxxx

Sowhere in the XEN-docs I read that vif Interfaces are transparent, but in this 
case they aren't.

So my Question is:
I this a bug? Otherwise I cannot find anything in the docs about this.
If this is the right behaviour, where can I change it?
I havent't found any filtering code neither in the backend nor the frontend 

Best regards,

Armin Kemper

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