Re: [Xen-users] Two bridges on one host, can not communicate on the second, what did I miss?

[Massimo Mongardini <massimo.mongardini@xxxxxxxxx>]

Anders,
   I have a similar working setup on xen 3.1 (dummy interface with 3 
bridges and 3 nics on a domU and 2 nics on other 3 domUs)
some thoughts:
- any filtering on the domUs or dom0 (iptables, ebtables)
- do you see mac addresses filling the bridges tables (brctl showmacs 
<bridgename>)?
- check /var/log/xen/
- maybe post "ip address list" "brctl show" from dom0 and "ip address 
list" from domU together with the comment's stripped xend-config and 
domU config.
cheers,
Massimo

Anders Andersson wrote:
> Hello! I'm trying to set up an "internal" bridge on a Xen host (xen
> 3.2, ubuntu server 8.04 as a host). I am trying to get domU A
> communicate with domU B, with no success.
>
> First I followed the instructions in the XenNetworking page on the
> wiki to get another bridge with no physical interface connected. I
> created a file called /etc/xen/scripts/network-custom:
>
> #!/bin/sh
> dir=$(dirname "$0")
> "$dir/network-bridge" "$@" vifnum=0
> "$dir/network-bridge" "$@" vifnum=1 bridge=dmz netdev=dummy0
>
> After a reboot, this bridge comes up fine, and the output from "brctl
> show" looks like the default bridge that the network-bridge script
> creates. I have now a pdummy0 interface configured as well, belonging
> to the bridge, but that is of course expected.
>
> After this I create two guests: domU_A and domU_B. They are both on
> the same network, 10.19.0.0/24, with IP number 10.19.0.2 and 10.19.0.3
> respectively. They just have one virtual network interface each, and I
> added "bridge=dmz" to them, so they will connect to the dmz bridge.
>
> After I start up both guests, I can see from "brctl show" that their
> vif1.0 and vif2.0 have been attached to the dmz bridge, and inside,
> the network interface has been configured correctly if I look at them
> using ifconfig.
>
> Here is where I fail. They can not access each other through the
> network, not with ping, nor with anything else.
>
> Using netcat gives me some slightly helpful message:
> domU_B:~# echo hello | nc 10.19.0.2 9999
> (UNKNOWN) [10.19.0.2] 9999 (?) : No route to host
>
>
> The output from "route" shows (sorry if the columns are not aligned correctly):
> Destination   Gateway  Genmask        Flags  Metric  Ref   Use Iface
> 10.19.0.0      *             255.255.255.0  U        0         0         0  eth0
>
> I don't have a default gateway, but well, there *is* no gateway, there
> are just two clients.
>
> The "ethtool -K eth0 tx off" trick doesn't make any difference.
>
> What's sad here is that networking within the default xen bridge works
> great, with exactly the same method of creating  and I have never had
> any problems with that. As a matter of fact, keeping the exact same
> config, but changing the bridge to the default bridge, makes it
> possible to communicate between the guests. But now I would like to
> add another bridge, as I would like to learn a little more about
> networking.
>
> Help! What did I miss? How can I find out where the problem is?
>
> / Anders
>
> _______________________________________________
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> http://lists.xensource.com/xen-users
>   

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